Soil Biota

Impact of Pesticides on Soil Biota

Soil biota can be affected directly or indirectly, through pesticide use and conventional farming technologies that promote the use of pesticides.

A study by LeBlanc et. al. in 2007 found that the rhizospheres (soil and microorganisms around the roots of a plant or tree) of Bacillus thuringiensis (Bt)-modified trees meant to alleviate insect damage had clear alterations when compared to the rhizospheres of non-Bt modified trees.
In 2013, a study by Anjum et. al. found that silver nanoparticles, a novel nanomaterial that the EPA recently agreed to regulate, has a profound effect on soil microorganisms, leading to a collapse in metabolic abilities and diversity in soils with low organic matter. Similar effects were found in soil with high organic matter, but to a lesser extent.
Earthworms are excellent indicators of soil health, and provide vitally important ecosystem services by aerating the soil, cycling nutrients, and increasing microbial activity:
Mycorrhizae fungi within soil are relied on by most plants for nutrients and moisture:

[See More Scientific Studies Below]

Economic Cost

The microbes in soil are essential to ecosystem functioning because they break down organic matter and enable chemical elements to be reused. They are also nitrogen fixers, which is necessary for plants and the ecosystem as a whole. Earthworms are an intrinsic part of soil biota, providing support for important ecosystem functioning. Their burrows, sometimes deep into the soil, create pores for moisture and oxygen to travel and their waste becomes part of soil structure. They also break down dead organic matter and incorporate new organic matter into soil systems.

When pesticides reduce species diversity within the soil, it impacts the ecosystem as a whole. The European Academies' Science Advisory Council (EASAC) estimates soil organisms and their role in agricultural productivity to be worth $25 billion a year, globally.

Litigation & Lawsuits

In early 2015, EPA finally agreed to regulate novel nanomaterial pesticides as a result of a lawsuit filed by Center for Food Safety (CFS) and joined by Beyond Pesticides in December. In 2008, a coalition of more than 13 organizations filed a legal petition requesting, among other things, that EPA recognize the risks associated with a growing class of nano-silver consumer products and regulate them as new pesticides. After EPA had failed to respond to the petition for six years, in December 2014 some of the petitioner groups sued the agency to force it to respond. That lawsuit succeeded in March 2015, with EPA issuing a response.

Quick Links

Groups Petition EPA to Stop Sale of Nanosilver Products (May 2008)
Lawsuit Challenges EPA’s Failure to Regulate Nanomaterial Pesticides (Dec. 2014)
Legal Petition Text
EPA’s Response

What Can You Do?

Learn about the Hazards and Alternatives to using lawn pesticides.
Go Organic – Visit our Eating with a Conscience page to learn why eating organic foods is the right choice.
Visit our Tools for Change page to learn how to organize your community against pesticide use.
Sign up for Beyond Pesticides’ Action Alerts to stay up-to-date on the latest petitions and news.
Scientific Studies:
- Bumblebee (Bombus impatiens) queens prefer pesticide-contaminated soils when selecting underground hibernation sites
  New evidence points to substantial impacts of exposure to pesticide residues in soil for a range of bee taxa that have close regular contact with this substrate. Among others, the risk of exposure is high for bumblebee (Bombus spp.) queens hibernating in agricultural soils. An important question is whether bumblebee queens can detect and avoid pesticide-contaminated soils, or whether they might be attracted to such agrochemical residues. To address this question, we performed a multiple-choice preference experiment in which newly emerged bumblebee (Bombus impatiens) queens were given access to arrays of 36 crates of soil treated with different pesticides in large mesh-covered enclosures. Five of the most commonly encountered pesticides in agricultural soils (boscalid, chlorantraniliprole, clothianidin, cyantraniliprole, difenoconazole) were selected for testing at two contamination levels (lower or higher), based on field-realistic exposure estimates. Bumblebee queens consistently avoided hibernating in pesticide-free soil at both contamination levels, while showing no avoidance for any pesticide-treated soil types. At the lower contamination level, queens selected the pesticide-free soil 1.3 to 2.4-fold less frequently on average than any of the spiked soils, while none of the queens from the higher contamination group selected pesticide-free soil. This apparent preference for pesticide-contaminated soils increases the likelihood of exposure to and potential hazard from pesticide residues in soil for bumblebee queens during hibernation, a critical and highly vulnerable period of their annual life cycle.
  [Rondeau, S. and Raine, N. (2024) Bumblebee (Bombus impatiens) queens prefer pesticide-contaminated soils when selecting underground hibernation sites, The Science of the Total Environment. Available at: https://pubmed.ncbi.nlm.nih.gov/39332727/. ]
- Direct evidence on the impact of organic amendments on carbon stabilization in soil microaggregates
  Direct evidence-based approaches are vital in understanding the involvement of abiotic/biotic factors and evaluating the newly proposed theories on soil carbon (C) stabilization. Microaggregates (150–250 µm) collected from a corn system (>22 years; Kansas, USA), which had been under no-till with different nitrogen (N) treatments were analyzed (N treatments: manure/compost, urea, zero fertilizer). We studied C stabilization in free soil microaggregates (with preserved aggregate architecture), directly using scanning transmission X-ray microscopy coupled with near edge X-ray absorption fine structure (STXM-NEXAFS) spectroscopy. Submicron scale findings were complemented with bulk chemical analysis. The STXM-NEXAFS analysis revealed soil organic carbon (SOC) preservation inside nano- and micro-pores and organo–mineral association, various degrees of humification, and high molecular diversity. The presence of microbial-derived C was found in manure-/compost-added microaggregates highlighting the contribution of organic amendments in facilitating microbial diversity. The incidence of aragonite-like minerals suggested the biologically/chemically active nature of microaggregate cores. Bulk analysis of free microaggregates showed a higher concentration of SOC (6.5%), ammonium oxalate extractable Fe/Al/Si), and higher aliphaticity of humic acid in manure-/compost-added soils compared to inorganic fertilizer (3% SOC) and control (2.7% SOC) treatments. The co-existence of elements (calcium [Ca]/C, iron [Fe]/N, Fe/C, aluminum [Al]/C, and silicon [Si]/C) was partially supported by bulk chemical analysis that indicated a strong association between ammonium oxalate extractable Fe/Al/Si and SOC (R2 = 0.63—0.77). Overall, our study provided direct/indirect evidence for the complex and interactive involvement of chemical, mineralogical, and biological mechanisms that may have been stimulated by the long-term addition of compost/manure in stabilizing SOC.
  [Pitumpe Arachchige, P.S. et al. (2024) Direct evidence on the impact of organic amendments on carbon stabilization in soil microaggregates, Soil Science Society of America. Available at: https://acsess.onlinelibrary.wiley.com/doi/10.1002/saj2.20701. ]
- Drivers and barriers to adoption of regenerative agriculture: cases studies on lessons learned from organic
  Regenerative agriculture has emerged as a potentially outcome-based paradigm centring on soil health, biodiversity and other environmental and social parameters. Early days of organic agriculture also focused on philosophy first and evolved into a process-based regulatory paradigm whose adoption remains small relative to conventional production. Five case studies of professional growers, representing a total of 100,000 acres of production, were collected to identify reasons for choosing to grow or stop growing organic, challenges faced and attitudes around regenerative agriculture. Growers identified issues of complex and unpredictable regulation, labour, inability to predict market trends and secure needed premiums, cost and effectiveness of natural fertilizers and lack of effectiveness in pest control. These growers adopted similar practices (e.g., integrated pest management) for environmental benefits across conventional and organic acres, and viewed consumer demand and potential profitability rather than environmental benefits as the main drivers for practising organic. Growers expressed interest in outcome-based regenerative agriculture. To be viable, a programme requires criteria on measurement and certification, regionally tailored flexibility and clear financial incentives. Growers doubt such a programme would replace organic but see opportunities for new marketing programmes, particularly in carbon sequestration and water management. Challenges identified by growers warrant further study.
  [Lemke, S. et al. (2024) Drivers and barriers to adoption of regenerative agriculture: cases studies on lessons learned from organic, International Journal of Agricultural Sustainability. Available at: https://www.tandfonline.com/doi/full/10.1080/14735903.2024.2324216. ]
- Effect of Mineral Fertilizers and Pesticides Application on Bacterial Community and Antibiotic-Resistance Genes Distribution in Agricultural Soils
  Soils are a hotspot for the emergence and spread of antibiotic resistance. The effects of agrochemical treatments on the bacterial community of agricultural soils and the content of antibiotic-resistance genes (ARGs) were studied. Treatments included the following: control, mineral fertilizers (NPKs), pesticides, and the combined treatment of soils under soya (Glycine max), sunflower (Helianthus annuus L.), and wheat (Triticum aestivum). Bacterial community taxonomic composition was studied using 16S rRNA gene sequencing. The content of 10 ARGs and 3 integron genes (intI1, intI2, intI3) was determined using quantitative real-time PCR. The results showed that the treatments had little effect on the taxonomic composition and diversity of the soil bacterial community. The most significant factors determining differences in the microbial community were sampling time and soil physico-chemical parameters. A significant role of the bacterial community in ARG distribution in soils was demonstrated. Representatives of the Pseudomonas, Bacillus, Sphingomonas, Arthrobacter genera, and the Nocardioidaceae and Micrococcaceae families were likely ARG hosts. The presence of integron genes of all three classes was detected, the most numerous being intI3. This work provides important information on the role of agricultural soils in ARG transfer, and the findings may be useful for sustainable and safe agricultural development.
  [Khmelevtsova, L. et al. (2024) Effect of mineral fertilizers and pesticides application on bacterial community and antibiotic-resistance genes distribution in agricultural soils, Agronomy. Available at: https://www.mdpi.com/2073-4395/14/5/1021]
- Effect of organic farming on root microbiota, seed production and pathogen resistance in winter wheat fields
  Societal Impact Statement
  Agricultural intensification is a major driver of biodiversity decline in agrosystems. For instance, it has been shown that conventional farming leads to a decline in soil microbial diversity and triggers a strong selection process, altering the functioning of the whole ecosystem. The present study shows that organic farming increases diversity and affects composition of crop plant microbiota, mostly as a response to field management and soil characteristics. Furthermore, crop plant microbiota influences crop production and resistance to pathogens. Therefore, agricultural practices affect plant performance through microorganism-mediated changes, which may be important pillars of future sustainable crop production.
  
  Summary
  Agricultural intensification threatens biodiversity, but the effects of intensification on microorganisms are still overlooked despite their role in ecosystem functioning. Microorganisms associated with plants provide many services that affect plant growth and health. Organic farming is expected to strongly affect species composition, richness, and their interactions. We analyzed the effect of the farming system on endophytic microbial assemblages associated with winter wheat plants and plant performance in the field.
  We collected environmental data through farmer interviews, soil analyses, and plant inventories and analyzed root microbiota at vegetative and flowering stages.
  Organic farming increased fungal and bacterial diversity associated to wheat plants and affected species composition in most phyla. This effect was mostly due to soil characteristics and field management and a little to plant diversity in the field. Microbial responses were more pronounced at the late developmental stage, likely as a result of accumulative effect of management actions during plant development. Seed production and resistance to pathogens were related to specific phyla that are important for seed production and/or wheat resistance to septoriose.
  This work advances our understanding of how agricultural practices affect plant performance through microorganism-mediated changes and supports the use of microorganisms as pillars of sustainable crop production.
  [Ricono, C. et al. (2024) Effect of organic farming on root microbiota, seed production and pathogen resistance in winter wheat fields, Plants, People, Planet. Available at: https://nph.onlinelibrary.wiley.com/doi/10.1002/ppp3.10602.]
- Effects of sustainable agricultural practices on soil microbial diversity, composition, and functions
  Soil microorganisms can provide multiple benefits to agroecosystems, which are assumed to be promoted by sustainable agricultural practices. However, the mechanisms that explain this relationship have not been clearly elucidated. Although studies have reported that sustainable agricultural practices promote microbial biomass, the broader implications for soil microbial composition and functions remain uncertain. Accordingly, we searched field experiments worldwide contrasting soil microbial communities under conventional and sustainable agricultural practices. We analysed 924 results of relative abundance of bacteria or fungi (using 16 S and ITS rRNA amplicon sequencing, respectively) at the Family taxonomic level obtained from 46 articles. We found higher soil bacterial richness and higher abundance of copiotrophic bacteria under sustainable agricultural practices. Organic fertilisation promoted the abundance of bacteria involved in C and N cycling, while conservation tillage decreased those involved in the decomposition of plant residue. While sustainable agricultural practices had a minor effect on the overall fungal structure, they led to increases in symbiotic fungi abundance (e.g., Geoglossaceae). Additionally, we observed a slight increase in arbuscular mycorrhizal fungi and a slight reduction in pathogenic fungi associated with plant disease (e.g., Botryosphaeriaceae). Higher soil microbial taxonomic diversity did not lead to increased soil multifunctionality; however, it could safeguard resilience for soil functions via the diversity insurance effect. This study establishes that sustainable agricultural practices can significantly influence microbial communities, leading to compositional and structural changes, as well as promoting relevant functions for agroecosystems. Altogether, these results highlight the importance of integrating concepts of community ecology into agricultural management practices for reaching sustainable agricultural systems.
  [Mondaca, P. et al. (2024) ‘Effects of sustainable agricultural practices on soil microbial diversity, composition, and functions’, Agriculture, Ecosystems & Environment, 370, p. 109053. doi:10.1016/j.agee.2024.109053.]
- Exploring negative emission potential of biochar to achieve carbon neutrality goal in China
  Limiting global warming to within 1.5 °C might require large-scale deployment of premature negative emission technologies with potentially adverse effects on the key sustainable development goals. Biochar has been proposed as an established technology for carbon sequestration with co-benefits in terms of soil quality and crop yield. However, the considerable uncertainties that exist in the potential, cost, and deployment strategies of biochar systems at national level prevent its deployment in China. Here, we conduct a spatially explicit analysis to investigate the negative emission potential, economics, and priority deployment sites of biochar derived from multiple feedstocks in China. Results show that biochar has negative emission potential of up to 0.92 billion tons of CO2 per year with an average net cost of US$90 per ton of CO2 in a sustainable manner, which could satisfy the negative emission demands in most mitigation scenarios compatible with China’s target of carbon neutrality by 2060.
  [Deng, X. et al. (2024) Exploring negative emission potential of biochar to achieve carbon neutrality goal in China, Nature Communications. Available at: https://www.nature.com/articles/s41467-024-45314-y. ]
- Harnessing soil carbon sequestration to address climate change challenges in agriculture
  Elevating levels of atmospheric carbon dioxide (CO2), primarily driven by the burning of fossil fuels, combustion of organic matter, and unsustainable land practices, have amplified global concerns regarding climate change. The industrial revolution has propelled the rise in CO2 emissions, leading to anticipated increases in concentrations and alterations in CO2 sequestration within agricultural soils. Land use alterations, encompassing deforestation, biomass burning, changes in agricultural conditions, drainage of natural wetlands, and incorrect soil management practices, have further amplified these emissions. Moreover, the reduction of soil organic carbon (SOC), an outcome of soil degradation and mismanagement, has intensified atmospheric CO2 levels. However, by implementing state-of-the-art land application and contemporary management systems in agriculture, there's potential to slow the rate of CO2 emissions. The restoration of depleted SOC is possible through various strategies, such as converting marginal lands into restorative uses, promoting reduced or zero-tillage practices combined with cover or residue crops, and implementing nutrient cycling via composting, manure application, and other sustainable soil and water management techniques. Long-term soil carbon sequestration is increasingly being viewed as a comprehensive strategy to combat climate change. By rejuvenating depleted soils, enhancing biomass production, purifying surface and groundwater, and offsetting CO2 emissions from fossil fuels, soil carbon sequestration can serve as a holistic and effective approach for mitigating current climatic changes. Adoption of these innovative techniques is crucial in managing the challenges imposed by recent environmental changes, positioning soil carbon sequestration as a promising solution. This review aims to explore the potential methods of mitigating climate change through the implementation of soil carbon sequestration strategies.
  [Nazir, M.J. et al. (2024) Harnessing soil carbon sequestration to address climate change challenges in agriculture, Soil and Tillage Research. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0167198723003264. ]
- Herbicides and pesticides synergistically interact at low concentrations in complex mixtures
  Assessing a complex mixture of pesticides at the impacted sites has been challenging for risk assessors for 50 years. The default assumption is that at low concentrations, pesticides interact additively with one another; thus, the risk posed by each component of a complex mixture could be simply added up. The EPA interaction-based hazard index (HIInteraction) modifies this assumption using a binary weight-of-evidence (BINWOE). However, data gaps often preclude HIInteraction use at most sites. This study evaluated these assumptions using the BINWOE to estimate the hazard index (HI) of select pesticide mixtures. The lack of in vivo binary interaction data led us to use a cell line, SH-SY5Y, to obtain the data necessary for the BINWOE approach. In the risk assessment, we considered the most active exposure scenario inhaling a mixture of volatile pesticides from contaminated soil and groundwater. The potential interactions between pesticides in 15 binary mixtures were investigated using the MTT assay in SH-SY5Y cells. Our findings showed that 60% of the binary mixtures elicited synergism (in at least one concentration), 27% displayed antagonism, and 13% showed additive effects in SH-SY5Y cells. Combining human safety data with in vitro interaction data indicated that adults and toddlers were at the highest risk when considering industrial and commercial land use, respectively, compared to other subpopulations. Incorporating interaction data into the risk assessment either increased the risk by up to 20% or decreased the risk by 2%, depending on the mixture. Our results demonstrate the predominant synergistic interactions, even at low concentrations, altered risk characterization at the complex operating site. Most concerning, organochlorine pesticides with the same mechanism of action did not follow dose additivity when evaluated by SH-SY5Y cell lines. Based on our observations, we caution that current HI methods based on additivity assumptions may underestimate the risk of organochlorine mixtures.
  [Alehashem, M. et al. (2024) Herbicides and pesticides synergistically interact at low concentrations in complex mixtures, Chemosphere. Available at: https://www.sciencedirect.com/science/article/pii/S0045653524003242?via%3Dihub. ]
- Impact of repeated fumigant applications on soil properties, crop yield, and microbial communities in a plastic-mulched tomato production system
  Pre-plant soil fumigation is widely applied to control nematodes, soil-borne fungal pathogens, and weeds in vegetable crops. However, most of the research evaluating the effect of fumigants on crop yield and soil microbial communities has been done on single compounds despite growers mainly applying fumigant combinations. We studied the effect of different fumigant combinations (chloropicrin, 1,3-dichloropropene, and metam potassium) on soil properties, crop yield, and the soil bacterial and fungal microbiome for two consecutive years in a plastic-mulched tomato production system in Florida (United States). While combinations of fumigants did not improve plant productivity more than the individual application of these products, application of fumigants with >60 % chloropicrin did significantly increase yield. Fumigant combinations had no significant effect on bacterial diversity, but fumigants with >35 % chloropicrin reduced soil fungal diversity and induced temporary changes in the soil bacterial and fungal community composition. These changes included short-term increases in the relative abundance of Firmicutes and Ascomycota, as well as decreases in other bacterial and fungal taxa. Repeated fumigation reduced network complexity and the relative abundance of several predicted bacterial functions and fungal guilds, particularly after fumigation and at end of harvest (3-months post fumigation). A structural equation model (SEM) showed fumigants not only directly impact crop yield, but they can also indirectly determine variations in plant productivity through effects on the soil microbiome. Overall, this study increases our understanding of the environmental and agricultural impacts of fumigants in a plastic-mulched tomato production system.
  [Castellano-Hinojosa, A. et al. (2024) Impact of repeated fumigant applications on soil properties, crop yield, and microbial communities in a plastic-mulched tomato production system, Science of The Total Environment. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0048969724007988. ]
- Influence of Pesticides Contamination on Microbial Population of Selected Farmlands
  Pesticides play a pivotal role in agriculture by combating various pests and increasing crop yields. However, extensive use of pesticides can result in unintended consequences, including potential impact on soil microbes. This study was aimed at investigating the influence of pesticides contamination on microbial population of farmlands in Otuoke, Nigeria. Soil samples were collected from four pesticide treated farmlands designated Bakery 1, Bakery 2, Dorcas, and PGS. A farmland without pesticide treatment served as Control. Microbial population, physiochemical parameters and pesticide residue of samples were investigated using standard techniques. Results revealed significant differences in microbial populations between pesticide-contaminated soils and control. The highest bacterium isolated and occurrence (%) in each location was; Streptomyces coelicolor 42(45.7%), Proteus vulgaris 179(59.9%), Streptomyces scabies 41(38.7%), Streptococcus pyrogenes 101(44.7%), and Pseudomonas aeruginosa 69(40.6%) for Bakery 1, Bakery 2, Dorcas, PGS, and control respectively. Highest fungus isolated and occurrence (%) was; Rhodotorula glutini 51(82.3%), 31(77.5%), and 43(81.1%) for Bakery 1, Bakery 2, and Dorcas respectively; and Candida tropicalis 25(80.6%) and Lichtheimia hyalospora 4(28.6%) for PGS and Control respectively. Pesticide analysis showed that Paraquat dichloride, Endosulfan, Diazinon, and N-(phosphonomethyl) glycine were present in the soil samples with about 75% residue. Site-specific pesticide concentrations varied in soil samples, with Bakery 1 having the highest concentrations Endosulfan and Diazinon, bakery 2 had highest concentration of N-(phosphonomethyl) glycine, and PGS had the highest concentration of Paraquat. Physiochemical characteristics showed that temperature ranged from 28.70 – 26.70°C, electrical conductivity 508 – 365µS/cm, moisture content 7.50 – 3.10%, pH 6.90 -3.90, and organic matter 4.70 – 3.00%. Decreasing order of cation exchange capacity (CEC) in farmlands was PGS > Bakery 2 > Bakery 1 > Dorcas > Control. There was no significant difference (p > 0.05) in each parameter between locations.
  [Uneze, D.P., Kugbenu, G.J. and Obire, O. (2024) Influence of pesticides contamination on microbial population of selected farmlands, British Journal of Environmental Sciences. Available at: https://eajournals.org/bjes/vol12-issue-5-2024/influence-of-pesticides-contamination-on-microbial-population-of-selected-farmlands/. ]
- Interaction between imidacloprid residues in maize rhizospheric soil and soil nematode community
  Although imidacloprid has been shown to present potential risks to non-target invertebrates and vertebrates, researches exploring this risk from the perspective of the underground ecosystem remains incomplete. In this study, we determined that the presence of imidacloprid significantly reduced the abundance and diversity of soil nematodes in maize rhizospheric soil. Furthermore, imidacloprid also exerted negative effects on the body length, reproduction, locomotion, lipid accumulation, lipofuscin accumulation, and acetylcholinesterase activity in the model organism Caenorhabditis elegans. These toxic phenotypes are correlated with the upregulation of fat-2, fat-6, hsp-16.41, and hsp-16.2, along with the downregulation of ace-1, ace-2, and ace-3. In response to these toxic effects of imidacloprid, nematodes also developed corresponding adaptive mechanisms. UPLC-MS/MS analysis revealed that nematodes could convert imidacloprid to imidacloprid-guanidine and imidacloprid-urea to reduce the toxicity of imidacloprid. Moreover, C. elegans and Meloidogyne incognita exhibited repellent behavior towards imidacloprid-treated area, even the concentration of imidacloprid is only 0.4 μg/mL. This study revealed the interaction between imidacloprid and nematodes, providing a basis for understanding the potential risks of non-target soil nematodes after application of imidacloprid in sustainable agriculture and the resistance mechanism of nematodes to nematocidal pesticide.
  [Zhang, J. et al. (2024) Interaction between imidacloprid residues in maize rhizospheric soil and soil nematode community, Pesticide Biochemistry and Physiology. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0048357524004528.]
- Interactions of traditional and biodegradable microplastics with neonicotinoid pesticides
  Neonicotinoid pesticides (NNPs) and microplastics (MPs) are two emerging contaminants in agricultural environment. However, the interaction between MPs (especially biodegradable plastics) and NNPs is currently unclear. Therefore, taking thiacloprid (THI) as an example of NNPs, this study explores the adsorption-desorption process and mechanism of NNPs on MPs (traditional and biodegradable plastics), and analyzed the main factors affecting the adsorption (pH, salinity and dissolved organic matter). In addition, by using diffusive gradients in thin-films device, this study assessed the impact of MPs on the bioavailability of NNPs in soil. The results showed that the maximum adsorption capacity of polyamide 6 (96.49 μg g-1) for THI was greater than that of poly (butylene adipate co-terephthalate) (88.78 μg g-1). Aging increased the adsorption amount of THI (5.53 %-15.8 %) due to the higher specific surface area and reduced contact angle of MPs, but the adsorption mechanism remained unchanged. The desorption amount of THI from MPs in simulated intestinal fluid is 1.30-1.36 times. The MPs in soil alter the distribution of THI in the soil, increasing the bioavailability of THI while inhibiting its degradation. The results highlighted the significance of examining the combined pollution caused by MPs and NNPs.
  [Wang, K. et al. (2024) Interactions of traditional and biodegradable microplastics with neonicotinoid pesticides, The Science of The Total Environment. Available at: https://pubmed.ncbi.nlm.nih.gov/38972406/. ]
- Investigating protistan predators and bacteria within soil microbiomes in agricultural ecosystems under organic and chemical fertilizer applications
  Organic farming can enhance biodiversity and soil health and is a sustainable alternative to conventional farming. Yet, soil protists especially protistan predators, have received inadequate attention, and their contributions to the sustainability of organic farming remained underexplored. In this study, we examined soil microbial communities from 379 samples, including both organic and chemically fertilized soils from China. Our findings revealed higher bacterial diversity and increases in plant-beneficial bacteria in organically farmed soils. Notably, organic farming systems facilitated dynamic predator-prey interactions, which may be disrupted by the application of chemical fertilizers. Additionally, organic farming enriched protistan predators, enhancing the relative abundance of functional PGPR, thus improving soil health. We further conducted a case study highlighting the critical role of organic matter in sustaining protistan predator populations and their interactions with bacteria. We propose the crucial contributions of organic inputs for supporting protistan predators and the interplay of predator-prey, ultimately enhancing soil functions and promoting agricultural sustainability.
  [Liu, C. et al. (2024) Investigating protistan predators and bacteria within soil microbiomes in agricultural ecosystems under organic and chemical fertilizer applications, Biology and Fertility of Soils . Available at: https://link.springer.com/article/10.1007/s00374-024-01845-6. ]
- Modeling pesticides and ecotoxicological risk assessment in an intermittent river using SWAT
  The present work aimed to predict the fate of two pesticides, copper (Cu) and glyphosate in a Mediterranean basin with an intermittent river and to assess the ecotoxicological risk related to their presence in water bodies coupling field measurements of streamflow and pesticide concentrations, and an eco-hydrological model. The Soil and Water Assessment Tool (SWAT) model was calibrated and, subsequently used to assess predicted environmental concentrations of pesticides in surface waters. The ecotoxicological risk related to the presence of Cu and glyphosate in surface water was assessed at the reach scale by using the Toxicity to Exposure Ratio approach (TER). Measurements of glyphosate concentrations (< 0.5 μg l−1) exceeded the maximum European threshold of environmental quality standards for pesticides (EQS) of 0.1 μg l−1. High concentrations of glyphosate were predicted in the wet season and in September, when glyphosate is mostly used in vineyards and olive grove productions. Acute risk (TER < 100) associated with the presence of glyphosate was detected for several reaches. High concentrations of Cu (< 6.5 μg l−1), mainly used as a fungicide in vineyards, were predicted in several river reaches. The results of the ecotoxicological risk assessment revealed that November and January were the critical months during which most of the river reaches showed a chronic risk associated with the presence of Cu.
  [Centanni, M. et al. (2024) Modeling pesticides and ecotoxicological risk assessment in an intermittent river using Swat, Scientific Reports. Available at: https://www.nature.com/articles/s41598-024-56991-6#Sec14. ]
- Organic farming promotes the abundance of fungi keystone taxa in bacteria-fungi interkingdom networks
  Soil bacteria-fungi interactions are essential in the biogeochemical cycles of several nutrients, making these microbes major players in agroecosystems. While the impact of the farming system on microbial community composition has been extensively reported in the literature, whether sustainable farming approaches can promote associations between bacteria and fungi is still unclear. To study this, we employed 16S, ITS, and 18S DNA sequencing to uncover how microbial interactions were affected by conventional and organic farming systems on maize crops. The Bray–Curtis index revealed that bacterial, fungal, and arbuscular mycorrhizal fungi communities were significantly different between the two farming systems. Several taxa known to thrive in healthy soils, such as Nitrosophaerales, Orbiliales, and Glomus were more abundant in the organic farming system. Constrained ordination revealed that the organic farming system microbial community was significantly correlated with the β-glucosidase activity, whereas the conventional farming system microbial community significantly correlated with soil pH. Both conventional and organic co-occurrence interkingdom networks exhibited a parallel node count, however, the former had a higher number of edges, thus being denser than the latter. Despite the similar amount of fungal nodes in the co-occurrence networks, the organic farming system co-occurrence network exhibited more than 3-fold the proportion of fungal taxa as keystone nodes than the conventional co-occurrence network. The genera Bionectria, Cercophora, Geastrum, Penicillium, Preussia, Metarhizium, Myceliophthora, and Rhizophlyctis were among the fungal keystone nodes of the organic farming system network. Altogether, our results uncover that beyond differences in microbial community composition between the two farming systems, fungal keystone nodes are far more relevant in the organic farming system, thus suggesting that bacteria-fungi interactions are more frequent in organic farming systems, promoting a more functional microbial community.
  [Matteoli, F.P. et al. (2024) ‘Organic farming promotes the abundance of fungi keystone taxa in bacteria-fungi interkingdom networks’, World Journal of Microbiology and Biotechnology, 40(4). doi:10.1007/s11274-024-03926-y.]
- Organic food has lower environmental impacts per area unit and similar climate impacts per mass unit compared to conventional
  In recent years, interest in studying the climate and environmental impact of organic food has grown. Here, we compared the environmental impacts of organic and conventional food using data from 100 life cycle assessment studies. Most studies focused on climate impacts, with fewer addressing biodiversity loss and ecotoxicity. Findings revealed no significant differences in global warming, eutrophication potential, and energy use per mass unit. However, organic food showed lower global warming, eutrophication potential, and energy use per area unit, with higher land use. Additionally, organic farming showed lower potential for biodiversity loss and ecotoxicity. Challenges in life cycle assessment include evaluating biodiversity, toxicity, soil quality, and carbon changes. The choice of functional units influences results, highlighting the importance of considering multiple units in assessing organic food’s environmental footprint. This study emphasizes the necessity for comprehensive assessments at both product and diet levels to support informed decisions.
  [Hashemi, F. et al. (2024) Organic food has lower environmental impacts per area unit and similar climate impacts per mass unit compared to conventional, Communications Earth & Environment. Available at: https://www.nature.com/articles/s43247-024-01415-6. ]
- Relationship between farming practices, soil macrofauna and litter decomposition in organic versus conventional banana agroecosystems
  Many agricultural practices used in conventional farming can have negative impacts on soil biodiversity and decomposition process. Conversion to organic farming could reduce the effect of these disturbances, but in situ consequences of these effects are still poorly investigated. In order to better support the ecological transition towards an organic agriculture in tropical agroecosystems, it is important to better understand the links between agricultural practices, soil macrofauna and the decomposition process. To reach this goal, we conducted a field experiment in banana agroecosystems in Martinique (Lesser Antilles). We selected six organic and six conventional banana fields located in two bioclimatic zones. In order to measure the microbial and macrofaunal contribution to decomposition, 264 litterbags, with either a small or large mesh size, were positioned and left in the field for three months. Glyphosate-contaminated and glyphosate-free banana leaf litters were tested. Biotic and abiotic field characteristics were measured. Our results confirmed the overall beneficial effect of converting to organic agriculture on the decomposition process (+24 %) for bananas leaf litter. Macrofaunal decomposition was increased more (55 %) than microbial decomposition (20 %), indicating that organic farming removes a constraint of conventional farming especially affecting macrofauna. Glyphosate contamination of the litter did not have a significant effect on overall litter decomposition. By using structural equations, we were able to link farming practices to macrofauna diversity and to decomposition process, through a cascading chain of effects. We found that organic farming enhanced macrofaunal contribution to decomposition by enhancing both macro-arthropod and earthworm richness by providing a diversity of microhabitats with dense and species-rich plant cover. Our results suggested a weak effect of the direct toxicity by glyphosate-contaminated litter ingestion, but an indirect effect of herbicides by destroying the soil weed cover providing resources and microhabitats for soil macrofauna. Soil weed cover thus appears to be an important element of the agroecosystem ensuring the sustainability of ecosystem processes.
  [Jaouhari, M., Damour, G. and Coulis, M. (2024) Relationship between farming practices, soil macrofauna and litter decomposition in organic versus conventional banana agroecosystems, Applied Soil Ecology. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0929139324004281. ]
- Size-dependent responses of colony-founding bumblebee (Bombus impatiens) queens to exposure to pesticide residues in soil during hibernation
  Bumblebees and other key pollinators are experiencing global declines, a phenomenon driven by multiple environmental stressors, including pesticide exposure. While bumblebee queens spend most of their life hibernating underground, no study to date has examined how exposure to pesticide-contaminated soils might affect bumblebee queens during this solitary phase of their lifecycle. We exposed Bombus impatiens queens (n = 303) to soil treated with field-realistic concentrations of two diamide insecticides (chlorantraniliprole and cyantraniliprole) and two fungicides (boscalid and difenoconazole), alone or combined, during a 30-week hibernation period. We found that exposure to boscalid residues in soil doubled the likelihood of queens surviving through the colony initiation period (after successful hibernation) and laying eggs. Our data also revealed complex interactions between pesticide exposure and queen body mass on aspects of colony founding. Among others, exposure to cyantraniliprole led to lethal and sublethal post-hibernation effects that were dependent on queen size, with larger queens showing higher mortality rates, delayed emergence of their first brood, and producing smaller workers. Our results show that effects of pesticide exposure depend on intrinsic traits of bumblebee queen physiology and challenge our understanding of how bees respond to pesticides under environmentally realistic exposure scenarios.
  [Rondeau, S. and Raine, N. (2024) Size-dependent responses of colony-founding bumblebee (Bombus impatiens) queens to exposure to pesticide residues in soil during hibernation, The Science of the Total Environment. Available at: https://pubmed.ncbi.nlm.nih.gov/39029756/. ]
- Soil chemical fumigation alters soil phosphorus cycling: effects and potential mechanisms
  Soil chemical fumigation is an effective and popular method to increase agricultural productivity. However, the broad-spectrum bioactivity of fumigants causes harm to soil beneficial microorganisms involved in the soil phosphorous cycle, such as soil phosphorus solubilizing microorganisms (PSMs). We review the effects of soil chemical fumigation on soil phosphorus cycling, and the potential underlying mechanisms that ultimately lead to altered phosphorus availability for crops. These complex processes involve the highly diverse PSM community and a plethora of soil phosphorus forms. We discuss phosphatizing amendments aimed at counteracting the possible negative effects of fumigation on phosphorus availability, phosphorus use efficiency, and crop yields. We also emphasize distinguishing between the effects on soil phosphorus cycling caused by the chemical fumigants, and those caused by the fumigation process (e.g. plastic mulching). These are typically conflated in the literature; distinguishing them is critical for identifying appropriate amendments to remediate possible post-fumigation soil phosphorus deficiencies.
  [Wang, Y. and Tang, D.W.S. (2024) Soil chemical fumigation alters soil phosphorus cycling: effects and potential mechanisms, Frontiers in Plant Science. Available at: https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1289270/full. ]
- The Role of Biodiversity in Agricultural Resilience: Protecting Ecosystem Services for Sustainable Food Production
  Biodiversity plays a fundamental role in enhancing agricultural resilience and sustaining food production by supporting critical ecosystem services. A diverse array of species within agroecosystems, from crops and livestock to soil organisms and pollinators, contributes to the stability, productivity, and adaptability of farming systems. This biodiversity-driven resilience is essential for mitigating the impacts of climate change, pests, diseases, and resource scarcity, which pose significant threats to global food security. Agricultural systems rich in biodiversity benefit from improved soil fertility, enhanced pollination, natural pest control, and water regulation, all of which reduce dependence on external inputs such as chemical fertilizers and pesticides. Moreover, maintaining genetic diversity within crops and livestock strengthens resilience against environmental stressors and promotes long-term sustainability. However, modern intensive agricultural practices, including monocropping and the overuse of agrochemicals, have resulted in significant biodiversity loss, compromising ecosystem health. This article explores the role of biodiversity in agricultural resilience, examines the threats posed by conventional farming practices, and discusses strategies for integrating biodiversity into agricultural systems to protect ecosystem services. By fostering biodiversity, farmers and policymakers can enhance the sustainability and resilience of agricultural landscapes, contributing to global food security in a changing climate.
  [Christianah, D. and Folarin, I. (2024) The Role of Biodiversity in Agricultural Resilience: Protecting Ecosystem Services for Sustainable Food Production, International Journal of Research Publication and Reviews. Available at: https://www.researchgate.net/publication/384848907_The_Role_of_Biodiversity_in_Agricultural_Resilience_Pr]
- A holistic review on trend, occurrence, factors affecting pesticide concentration, and ecological risk assessment
  Demographic outbursts and increased food demands invoke excessive use of pesticides in the agricultural field for increasing productivity which leads to the relentless decline of riverine health and its tributaries. These tributaries are connected to a plethora of point and non-point sources that transport pollutants including pesticides into the Ganga river's mainstream. Simultaneous climate change and lack of rainfall significantly increase pesticide concentration in the soil and water matrix of the river basin. This paper is intended to review the paradigm shift of pesticide pollution in the last few decades in the river Ganga and its tributaries. Along with this, a comprehensive review suggests the ecological risk assessment method which facilitates policy development, sustainable riverine ecosystem management, and decision-making. Before 2011, the total mixture of Hexachlorocyclohexane was found at 0.004-0.026 ng/mL in Hooghly, but now, the concentration has increased up to 0.465-4.132 ng/mL. Aftermath of critical review, we observed maximum residual commodities and pesticide contamination reported in Uttar Pradesh > West Bengal > Bihar > Uttara Khand possibly because of agricultural load, increasing settlement, and incompetency of sewage treatment plant in the reclamation of pesticide contamination.
  [Singh, R.P., Mahajan, M., Gandhi, K., Gupta, P.K., Singh, A., Singh, P., Singh, R.K. and Kidwai, M.K., 2023. Environmental Monitoring and Assessment, 195(4), p.451.]
- A review on arsenic in the environment: contamination, mobility, sources, and exposure
  Arsenic is one of the regulated hazard materials in the environment and a persistent pollutant creating environmental, agricultural and health issues and posing a serious risk to humans. In the present review, sources and mobility of As in various compartments of the environment (air, water, soil and sediment) around the World are comprehensively investigated, along with measures of health hazards. Multiple atomic spectrometric approaches have been applied for total and speciation analysis of As chemical species. The LoD values are basically under 1 μg L−1, which is sufficient for the analysis of As or its chemical species in environmental samples. Both natural and anthropogenic sources contributed to As in air, while fine particulate matter tends to have higher concentrations of arsenic and results in high concentrations of As up to a maximum of 1660 ng m−3 in urban areas. Sources for As in natural waters (as dissolved or in particulate form) can be attributed to natural deposits, agricultural and industrial effluents, for which the maximum concentration of 2000 μg L−1 was found in groundwater. Sources for As in soil can be the initial contents, fossil fuel burning products, industrial effluents, pesticides, and so on, with a maximum reported concentration up to 4600 mg kg−1. Sources for As in sediments can be attributed to their reservoirs, with a maximum reported concentration up to 2500 mg kg−1. It is notable that some reported concentrations of As in the environment are several times higher than permissible limits. However, many aspects of arsenic environmental chemistry including contamination of the environment, quantification, mobility, removal and health hazards are still unclear.
  [Patel, K.S. et al. (2023) A review on arsenic in the environment: Contamination, mobility, sources, and exposure, RSC advances. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10020839/. ]
- Directly Fluorinated Containers as a Source of Perfluoroalkyl Carboxylic Acids
  Direct fluorination of plastics is performed to impart chemical resistance via exposure of polyethylene to fluorine gas to produce a fluorine-modified surface layer. Leaching experiments were performed on a directly fluorinated container under various conditions and with different matrices, including foodstuffs. The average sum of per- and polyfluoroalkyl substances (PFAS) concentrations measured from extraction of a fluorinated container was 63.75 ± 13.2 ng/g plastic. Seven-day leaching experiments of fluorinated containers with water, methanol, and acetone produced sums of PFAS concentrations that ranged from 0.99 to 66.92 ng/g plastic. Leaching experiments with food matrices produced sums of PFAS concentrations ranging from 2.66 to 7.19 ng/g plastic. A subset of samples subjected to leaching at elevated temperatures generated sums of PFAS concentrations up to 830% higher. In all experiments, short-chain perfluoroalkyl carboxylic acids (PFCAs) were detected in the highest frequencies and concentrations with analyte concentration decreasing as chain length increased. An estimate for PFAS released into food ranged from 0.77 to 2.68 ng/kg body weight per week, showing ingestion of food stored in these containers could be a significant source of exposure. Based on the large number of applications where directly fluorinated containers find use, the observation of PFAS migration suggests use regulations are warranted, and future studies should explore their fate when disposed or recycled.
  [Whitehead, H.D. and Peaslee, G.F., 2023. Environmental Science & Technology Letters, 10(4), pp.350-355.]
- Driving factors on accumulation of cadmium, lead, copper, zinc in agricultural soil and products of the North China Plain
  The accumulation of heavy metals in agricultural soils concerns food security. By using the Geographical Detector, this study investigated the influence of six types of factors (eleven factors) on the accumulation of Cd, Pb, Cu, Zn in agricultural soil and products of the North China Plain and confirmed the dominant factor. The results showed that heavy metals had accumulated in regional agricultural soils and the accumulation of Cd was severe. The accumulation of heavy metals was significantly influenced by policy factors (the management and reduction in usage of fertilizers and pesticides), fertilization factors (application of organic and chemical fertilizers), pesticide factors (application of herbicide and insecticide) and atmospheric deposition factors (heavy metal concentration in atmospheric deposition). The policy factor dominated the other three types of factors. Atmospheric deposition and the excess application of fertilizers and pesticides directly lead to the accumulation of heavy metals. Due to the high concentrations of heavy metals and abundant application amounts, organic fertilizers have contributed high levels of heavy metals to agricultural soils. This study suggests that formulated fertilization and action plans for pesticide reduction could effectively decrease the accumulation of heavy metals in agricultural soils and products in the study area.
  [Liu, Z., Bai, Y., Gao, J. and Li, J., 2023. Scientific Reports, 13(1), p.7429.]
- Farmer perspectives on carbon markets incentivizing agricultural soil carbon sequestration
  Climate change mitigation efforts to achieve net-zero emissions require not only decreasing current greenhouse gas emissions, but also the deployment of negative emissions technologies. Soil organic carbon sequestration in agricultural lands is one such negative emissions strategy, currently being incentivized predominantly through voluntary carbon offset markets. Through semi-structured interviews, we assess both conventional and organic farmer perspectives on soil carbon offset programs that have been created in the United States since 2017. The perspectives of farmers both participating and not participating in agricultural soil carbon markets were similar and consistent. Farmers in both groups expressed concerns about the convoluted, burdensome and unpredictable nature of receiving offset credits and emphasized that they were implementing practices for their own business interests and sustainability concerns, not the financial incentive of the generation of carbon credits. Based on our research, carbon offset credit payments for agricultural soil carbon sequestration are largely reaching farmers who were already implementing these beneficial practices or were already strongly interested in implementing these practices, and the payments for the offset credits are seen as a ‘gravy on top’, suggesting that these offset markets face strong challenges of ensuring true additionality essential to effective climate mitigation.
  [Barbato, C.T. and Strong, A.L. (2023) Farmer perspectives on carbon markets incentivizing agricultural soil carbon sequestration, Climate Action. Available at: https://www.nature.com/articles/s44168-023-00055-4. ]
- Interactions of Microplastics with Pesticides in Soils and Their Ecotoxicological Implications
  Abstract
  
  In the middle of the 20th century, the production of plastics exploded worldwide because of their low cost and the versatility of their applications. However, since plastic debris is highly resistant to environmental degradation, a growing presence of plastics in all the ecosystems has been confirmed. Among them, plastic particles < 5 mm, also known as microplastics (MPs), are of special concern because they are dispersed in aerial, terrestrial and aquatic environments, being the soil the main environmental sink of these contaminants. Due to their large specific surface area and hydrophobicity, MPs are considered good adsorbents for other environmental organic pollutants also present in terrestrial ecosystems, such as pharmaceuticals, personal-care products or pesticides with which they can interact and thus modify their environmental fate. In this review article, we examine the recent literature (from 2017 to 2022) to get a better understanding of the environmental fate of pesticides in soil (adsorption, mobility and/or degradation) when they are simultaneously present with MPs and the ecological risks on living organisms of the interactions between MPs and pesticides in soil. More studies are needed to fully understand the toxicological impact of the copresence in soil of pesticides and MPs.
  
  [Peña, A., Rodríguez-Liébana, J.A. and Delgado-Moreno, L. (2023) ‘Interactions of microplastics with pesticides in soils and their ecotoxicological implications’, Agronomy, 13(3), p. 701. doi:10.3390/agronomy13030701. ]
- Metabolic Consequences of the Water We Drink: A Study Based on Field Evidence and Animal Model Experimentation
  The effect of the chronic consumption of water contaminated with residual concentrations of DDT's metabolites (DDD-dichlorodiphenyldichloroethane and DDE-dichlorodiphenyldichloroethylene) found in the environment were evaluated on the biometric, hematological and antioxidant system parameters of the hepatic, muscular, renal and nervous tissues of Wistar rats. The results showed that the studied concentrations (0.002 mg.L-1 of DDD plus 0.005 mg.L-1 of DDE) could not cause significant changes in the hematological parameters. However, the tissues showed significant alteration in the activity of the antioxidant system represented by the increase in the activity of the enzymes gluthathione S-transferases in the liver, superoxide dismutase in the kidney, gluthathione peroxidase in the brain, and several changes in enzymatic activity in muscle (SOD, GPx and LPO). The enzymes alanine aminotransaminase (ALT) and aspartate aminotransaminase (AST) were also evaluated for the amino acids' metabolism in the liver, with ALT showing a significant increase in the exposed animals. In the integrative analysis of biomarkers (Permanova and PCOA), the studied concentrations showed possible metabolic changes and damage to cellular structures evidenced by increased oxidative stress and body weight gain among the treated animals. This study highlights the need for further studies on the impact of banned pesticides still present in soils that may induce adverse effects in organisms that may prevail in future generations and the environment.
  [Wolfart, J.C., Theodoro, J.L., Silva, F.C., de Oliveira, C.M.R., Ferreira, N.G. and Bittencourt Guimarães, A.T., 2023. Toxics, 11(4), p.315.]
- Persistence of triclopyr, dicamba, and picloram in the environment following aerial spraying for control of dense pine invasion
  Aerial application of an herbicide mixture of triclopyr, dicamba, picloram, and aminopyralid is used to control dense infestations of exotic conifers, notably lodgepole pine (Pinus contorta Douglas ex Loudon), in New Zealand. The rates of herbicide applied to control these tree weeds has the potential for off-target impacts through persistence in the forest floor, soil, and water. Persistence of three of these herbicides was investigated in cast needles, forest floor (litter, fermented humic layer [LFH]), and soil following their operational aerial application (triclopyr: 18 kg ai ha−1; dicamba: 5 kg ai ha−1; picloram: 2 kg ai ha−1) at three sites across New Zealand (KF, MD, GE) with dense invasions of P. contorta. Water was collected from a local stream at two sites (KF, MD) in the days/months after spraying. Active ingredients detected across all sites in cast needles, LFH, and mineral soil generally reflected their application rates, with total amounts comprising 81% triclopyr, 14% dicamba, and 5% picloram. Most of the active ingredients were detected in the LFH (59%), a heavy lignin-rich layer of dead needles overlaying the soil. All three herbicides persisted in this layer, at all sites, for up to 2 yr (at study termination). Only triclopyr was detected in mineral soil, where it declined to below detection levels (0.2 mg kg−1) within 1 yr. All three herbicides were detected in stream water on the day of spray application at KF, and during a rainfall event 1 mo later. However, amounts did not exceed New Zealand environmental and drinking water standards, an outcome attributed to a 30-m no-spray buffer zone used at this site. At MD, herbicides were detectable in water up to 4 mo after spraying, with amounts exceeding New Zealand drinking water standards on one occasion, 1 mo after spray application. No spray buffer zones were used at the MD site.
  [Rolando, C.A. et al. (2023) Persistence of Triclopyr, dicamba, and Picloram in the environment following aerial spraying for control of dense pine invasion, Invasive Plant Science and Management. Available at: https://www.cambridge.org/core/journals/invasive-plant-science-and-management/article/persistence-of-triclopyr-dicamba-and-picloram-in-the-environment-following-aerial-spraying-for-control-of-dense-pine-invasion/EC888894C5B7A927AD5E5A3E0C06CD8D. ]
- Plastic contamination in agricultural soils: a review
  Researchers are focused on the global issue of plastic contamination in agricultural soils because of the known effects of plastics on the soil ecosystem. Previous reviews did not pay attention to plastic sources, standardized extraction methods, soil characterization, and the abundance of plastics in agricultural soils. This study aims to review up-to-the-minute knowledge about plastic contamination studies, suggest the best method for microplastic studies, and propose future research areas. The research about plastic contamination in agricultural soils published from January 2018 to March 2022 was reviewed for this review article. Studies focusing on microplastics in soils other than agricultural soils were not considered in the present review. The data were acquired from several databases, namely Web of Science and Google Scholar. The keywords used to search these databases were "microplastics AND agricultural soils" and "macroplastics AND agricultural soils". Other literature sources were obtained from the reference lists of downloaded articles, and other pieces of literature that directly dealt with macroplastic and microplastic contamination in agricultural soils were obtained from relevant journals and books. Overall, 120 sources of literature, including 102 original research articles, 13 review articles, and five books, were selected, reviewed, and synthesized. As expected, agricultural soils, including arable lands, paddy lands, uplands, irrigation, and greenhouse soils, receive plastic contaminants. The contaminants of different sizes and forms are distributed spatially and temporally in the surface, subsurface, and profiles of the agricultural soils. Unlike previous studies that reported many studies on sewage sludge, the significant sources of plastic contamination in the agricultural soils included mulching, sludge and compost placement, and greenhouses abandonment. The distribution of plastic contamination studies in the agricultural lands is Asia: 60%; Europe: 29%; Africa: 4%; North America: 4%; Latin America: 3%; and Australia: 0%. After careful analysis of the methods used for the plastics contamination studies, the study concluded that floatations with low-density solutions such as distilled water and NaCl are efficient in separating light-density microplastics. In contrast, ZnCl and NaI are incredibly efficient in separating the heavy-density microplastics. Moreover, this review provides insight for future research in the field.
  [Sa’adu, I. and Farsang, A. (2023) Plastic contamination in agricultural soils: A Review, Environmental Sciences Europe. Available at: https://enveurope.springeropen.com/articles/10.1186/s12302-023-00720-9. ]
- Advances and future prospects of pyrethroids: Toxicity and microbial degradation
  Pyrethroids are a class of insecticides structurally similar to that of natural pyrethrins. The application of pyrethrins in agriculture and pest control lead to many kinds of environmental pollution affecting human health and loss of soil microbial population that affect soil fertility and health. Natural pyrethrins have been used since ancient times as insect repellers, and their synthetic versions especially type 2 pyrethroids could be highly toxic to humans. PBO (Piperonyl butoxide) is known to enhance the toxicity of prallethrin in humans due to the resistance in its metabolic degradation. Pyrethroids are also known to cause plasma biochemical profile changes in humans and they also lead to the production of high levels of reactive oxygen species. Further they are also known to increase SGPT activity in humans. Due to the toxicity of pyrethrins in water bodies, soils, and food products, there is an urgent need to develop sustainable approaches to reduce their levels in the respective fields, which are eco-friendly, economically viable, and socially acceptable for on-site remediation. Keeping this in view, an attempt has been made to analyse the advances and prospects in using pyrethrins and possible technologies to control their harmful effects. The pyrethroid types, composition and biochemistry of necessary pyrethroid insecticides have been discussed in detail, in the research paper, along with their effect on insects and humans. It also covers the impact of pyrethroids on different plants and soil microbial flora. The second part deals with the microbial degradation of the pyrethroids through different modes, i.e., bioaugmentation and biostimulation. Many microbes such as Acremonium, Aspergillus, Microsphaeropsis, Westerdykella, Pseudomonas, Staphylococcus have been used in the individual form for the degradation of pyrethroids, while some of them such as Bacillus are even used in the form of consortia.
  [Singh, S. et al. (2022) Advances and future prospects of pyrethroids: Toxicity and microbial degradation, Science of The Total Environment. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0048969722016540. ]
- Outside the Safe Operating Space of a New Planetary Boundary for Per- and Polyfluoroalkyl Substances (PFAS)
  It is hypothesized that environmental contamination by per- and polyfluoroalkyl substances (PFAS) defines a separate planetary boundary and that this boundary has been exceeded. This hypothesis is tested by comparing the levels of four selected perfluoroalkyl acids (PFAAs) (i.e., perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), and perfluorononanoic acid (PFNA)) in various global environmental media (i.e., rainwater, soils, and surface waters) with recently proposed guideline levels. On the basis of the four PFAAs considered, it is concluded that (1) levels of PFOA and PFOS in rainwater often greatly exceed US Environmental Protection Agency (EPA) Lifetime Drinking Water Health Advisory levels and the sum of the aforementioned four PFAAs (Σ4 PFAS) in rainwater is often above Danish drinking water limit values also based on Σ4 PFAS; (2) levels of PFOS in rainwater are often above Environmental Quality Standard for Inland European Union Surface Water; and (3) atmospheric deposition also leads to global soils being ubiquitously contaminated and to be often above proposed Dutch guideline values. It is, therefore, concluded that the global spread of these four PFAAs in the atmosphere has led to the planetary boundary for chemical pollution being exceeded. Levels of PFAAs in atmospheric deposition are especially poorly reversible because of the high persistence of PFAAs and their ability to continuously cycle in the hydrosphere, including on sea spray aerosols emitted from the oceans. Because of the poor reversibility of environmental exposure to PFAS and their associated effects, it is vitally important that PFAS uses and emissions are rapidly restricted.
  [Cousins, I.T., Johansson, J.H., Salter, M.E., Sha, B. and Scheringer, M. Environmental Science & Technology.]
- PFAS Molecules: A Major Concern for the Human Health and the Environment
  Per- and polyfluoroalkyl substances (PFAS) are a group of over 4700 heterogeneous compounds with amphipathic properties and exceptional stability to chemical and thermal degradation. The unique properties of PFAS compounds has been exploited for almost 60 years and has largely contributed to their wide applicability over a vast range of industrial, professional and non-professional uses. However, increasing evidence indicate that these compounds represent also a serious concern for both wildlife and human health as a result of their ubiquitous distribution, their extreme persistence and their bioaccumulative potential. In light of the adverse effects that have been already documented in biota and human populations or that might occur in absence of prompt interventions, the competent authorities in matter of health and environment protection, the industries as well as scientists are cooperating to identify the most appropriate regulatory measures, substitution plans and remediation technologies to mitigate PFAS impacts. In this review, starting from PFAS chemistry, uses and environmental fate, we summarize the current knowledge on PFAS occurrence in different environmental media and their effects on living organisms, with a particular emphasis on humans. Also, we describe present and provisional legislative measures in the European Union framework strategy to regulate PFAS manufacture, import and use as well as some of the most promising treatment technologies designed to remediate PFAS contamination in different environmental compartments.
  [Panieri, E. et al. (2022) Pfas molecules: A major concern for the human health and the environment, Toxics. Available at: https://www.mdpi.com/2305-6304/10/2/44. ]
- Quantifying exposure of bumblebee (Bombus spp.) queens to pesticide residues when hibernating in agricultural soils
  Exposure to pesticides is a major threat to bumblebee (Bombus spp.) health. In temperate regions, queens of many bumblebee species hibernate underground for several months, putting them at potentially high risk of exposure to soil contaminants. The extent to which bumblebees are exposed to residues in agricultural soils during hibernation is currently unknown, which limits our understanding of the full pesticide exposome for bumblebees throughout their lifecycle. To generate field exposure estimates for overwintering bumblebee queens to pesticide residues, we sampled soils from areas corresponding to suitable likely hibernation sites at six apple orchards and 13 diversified farms throughout Southern Ontario (Canada) in fall 2019-2020. Detectable levels of pesticides were found in 65 of 66 soil samples analysed for multi-pesticide residues (UPLC-MS/MS). A total of 53 active ingredients (AIs) were detected in soils, including 27 fungicides, 13 insecticides, and 13 herbicides. Overall, the frequency of detection, residue levels (median = 37.82 vs. 2.20 ng/g), and number of pesticides per sample (mean = 12 vs. 4 AIs) were highest for orchard soils compared to soils from diversified farms. Ninety-one percent of samples contained multiple residues (up to 29 different AIs per sample), including mixtures of insecticides and fungicides that might lead to synergistic effects. Our results suggest that when hibernating in agricultural areas, bumblebee queens are very likely to be exposed to a wide range of pesticide residues in soil, including potentially harmful levels of insecticides (e.g., cyantraniliprole up to 148.82 ng/g). Our study indicates the importance of empirically testing the potential effects of pesticide residues in soils for hibernating bumblebee queens, using field exposure data such as those generated here. The differences in potential exposure that we detected between cropping systems can also be used to better inform regulations that govern the use of agricultural pesticides, notably in apple orchards.
  [Rondeau, S. et al. (2022) Quantifying exposure of bumblebee (Bombus spp.) queens to pesticide residues when hibernating in agricultural soils, Environmental Pollution. Available at: https://pubmed.ncbi.nlm.nih.gov/35809712/. ]
- Response of microbial antibiotic resistance to pesticides: An emerging health threat
  The spread of microbial antibiotic resistance has seriously threatened public health globally. Non-antibiotic stressors have significantly contributed to the evolution of bacterial antibiotic resistance. Although numerous studies have been conducted on the potential risk of pesticide pollution for bacterial antibiotic resistance, a systematic review of these concerns is still lacking. In the present study, we elaborate the mechanism underlying the effects of pesticides on bacterial antibiotic resistance acquisition as well as the propagation of antimicrobial resistance. Pesticide stress enhanced the acquisition of antibiotic resistance in bacteria via various mechanisms, including the activation of efflux pumps, inhibition of outer membrane pores for resistance to antibiotics, and gene mutation induction. Horizontal gene transfer is a major mechanism whereby pesticides influence the transmission of antibiotic resistance genes (ARGs) in bacteria. Pesticides promoted the conjugation transfer of ARGs by increasing cell membrane permeability and increased the proportion of bacterial mobile gene elements, which facilitate the spread of ARGs. This review can improve our understanding regarding the pesticide-induced generation and spread of ARGs and antibiotic resistant bacteria. Moreover, it can be applied to reduce the ecological risks of ARGs in the future.
  [Qiu, D. et al. (2022) Response of microbial antibiotic resistance to pesticides: An emerging health threat, Science of The Total Environment. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0048969722051567. ]
- Soil protists: An untapped microbial resource of agriculture and environmental importance
  Protists are essential components of soil biodiversity and ecosystem functioning. They play a vital role in the microbial food web as consumers of bacteria, fungi, and other small eukaryotes and are also involved in maintaining soil fertility and plant productivity. Protists also contribute to regulating and shaping the bacterial community in terrestrial ecosystems via specific prey spectra. They play a role in plant growth promotion and plant health improvement, mostly via nutrient cycling, grazing, and the activation of bacterial genes required for plant growth and phytopathogen suppression. Thus, protists may prove to be a useful inoculant as biofertilizer and biocontrol agent. They can also be applied as model organisms as bioindicators of soil health. Despite their usefulness and essentiality, they are often forgotten and under-researched components of the soil microbiome, as most of our research focuses on bacteria and fungi. In this review, we provide an overview of the role of protists in plant productivity and plant health management and in shifts in soil bacterial community composition, as well as their roles as bioindicator. We also discuss the perspectives of knowledge gaps and future prospects to further improve soil biology. More research in soil protistology will provide insights into sustainable agriculture and environmental health alongside the study of bacteria and fungi.
  [Chandarana, K. and Amaresan, N. (2022) Soil protists: An untapped microbial resource of agriculture and environmental importance, Pedosphere. Available at: https://www.sciencedirect.com/science/article/abs/pii/S1002016021600668. ]
- Studies on the abilities of uptake and translocation from root to shoot of pesticides in soil
  The uptake experiments with pesticides were performed to clarify differences among plant species, and the influence of growth stages and conditions on the uptake and translocation ability of pesticides. There were 2–10-fold differences among plant species in the root and shoot concentrations of each pesticide, and shoot concentrations of pesticides in Brassica rapa L. var. perviridis were relatively high. In addition, the changes in shoot concentrations with growth stage of B. rapa were affected by root system development. The influence of temperature on uptake and translocation ability differed for each pesticide, while uptake and translocation ability were high for short day lengths. This indicated that plant uptake and translocation of pesticides were affected by root system development and growth conditions such as temperature and day length, not only the relationships to the chemical’s properties and behavior of organic chemicals in the soil.
  [Namiki, S. (2022) Studies on the abilities of uptake and translocation from root to shoot of pesticides in soil, Journal of Pesticide Science. Available at: https://www.jstage.jst.go.jp/article/jpestics/47/3/47_J22-01/_article. ]
- Targeted analysis and Total Oxidizable Precursor assay of several insecticides for PFAS
  Targeted analysis for 24 Per- and Polyfluoroalkyl Substances (PFAS) was conducted on 10 insecticide formulations used on a United States Department of Agriculture crop research field. Perfluorooctane sulfonic acid (PFOS) was found in 6 of the 10 formulations with concentrations ranging from 3.92 to 19.2 mg/kg. Further analysis of soil and plant samples collected at the site found several additional PFAS, with PFOS being the most prominent. Suspect screening was then conducted on the formulations and provided several suspected PFAS in addition to the 24 targeted analyzed PFAS in 7 of the 10 samples, one of which showed no PFAS during targeted analysis. PFAS-precursor oxidation was then conducted on the two insecticide formulations with the greatest lists of suspected PFAS as validation of potential unknown PFAS in the formulations. This study revealed a previously unknown potential PFAS contamination source for rural and agricultural environments.
  [Lasee, S. et al. (2022) Targeted analysis and Total Oxidizable Precursor assay of several insecticides for PFAS, Journal of Hazardous Materials Letters. Available at: https://www.sciencedirect.com/science/article/pii/S266691102200020X#! ]
- An evaluation of biological soil health indicators in four long-term continuous agroecosystems in Canada
  The soil microbial community (SMC) and soil organic matter (SOM) are inherently related and are sensitive to land-use changes. Microorganisms regulate essential soil functions that are key to SOM dynamics, whereas SOM dynamics define the SMC. To expand our understanding of soil health, we evaluated biological and SOM indicators in long-term (18-yr) continuous silage corn (Zea mays L.), continuous soybean [Glycine max (L.) Merr.], and perennial grass ecosystems in Ontario, Canada. The SMC was evaluated via ester-linked fatty acid methyl ester (EL-FAME) and amplicon sequencing. Soil organic matter was evaluated via a new combined enzyme assay that provides a single biogeochemical cycling value for C, N, P, and S cycling activity (CNPS), as well as loss-on-ignition, permanganate oxidizable C (POXC), and total C and N. Overall, soil health indicators followed the trend of grasses > corn > soybean. Grass systems had up to 8.1 times more arbuscular mycorrhizal fungi, increased fungal/bacteria ratios (via EL-FAME), and higher microbial diversity (via sequencing). The POXC was highly variable within treatments and did not significantly differ between systems. The novel CNPS activity assay, however, was highly sensitive to management (up to 2.2 and 3.2 times higher under grasses than corn and soybean, respectively) and was positively correlated (ρ > .92) to SOM, total C, and total N. Following the “more is better” model, where higher values of the measured parameters indicate a healthier soil, our study showed decreased soil health under monocultures, especially soybean, and highlights the need to implement sustainable agriculture practices that maintain soil health.
  [Pérez‐Guzmán, L., Phillips, L.A., Seuradge, B.J., Agomoh, I., Drury, C.F. and Acosta‐Martínez, V. Agrosystems, Geosciences & Environment, 4(2), p.e20164.]
- Protists as main indicators and determinants of plant performance
  Background
  Microbiomes play vital roles in plant health and performance, and the development of plant beneficial microbiomes can be steered by organic fertilizer inputs. Especially well-studied are fertilizer-induced changes on bacteria and fungi and how changes in these groups alter plant performance. However, impacts on protist communities, including their trophic interactions within the microbiome and consequences on plant performance remain largely unknown. Here, we tracked the entire microbiome, including bacteria, fungi, and protists, over six growing seasons of cucumber under different fertilization regimes (conventional, organic, and Trichoderma bio-organic fertilization) and linked microbial data to plant yield to identify plant growth-promoting microbes.
  
  Results
  Yields were higher in the (bio-)organic fertilization treatments. Soil abiotic conditions were altered by the fertilization regime, with the prominent effects coming from the (bio-)organic fertilization treatments. Those treatments also led to the pronounced shifts in protistan communities, especially microbivorous cercozoan protists. We found positive correlations of these protists with plant yield and the density of potentially plant-beneficial microorganisms. We further explored the mechanistic ramifications of these relationships via greenhouse experiments, showing that cercozoan protists can positively impact plant growth, potentially via interactions with plant-beneficial microorganisms including Trichoderma, the biological agent delivered by the bio-fertilizer.
  
  Conclusions
  We show that protists may play central roles in stimulating plant performance through microbiome interactions. Future agricultural practices might aim to specifically enhance plant beneficial protists or apply those protists as novel, sustainable biofertilizers.
  [Guo, S. et al. (2021) Protists as main indicators and determinants of plant performance, Microbiome. Available at: https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-021-01025-w. ]
- Winter cover crops shape early-season predator communities and trophic interactions
  Despite the dynamic nature of annual cropping systems, few studies have investigated how the structure of predator communities and their interactions with prey corresponds with crop seasonality. Adding winter habitat, such as cover crops, improves soil health and likely contributes seasonal habitat availability for arthropod communities. Stable habitat may lead to functionally diverse predatory communities and their associated ecosystem services, such as biological control. Here, we estimated predatory community functional changes based on foraging traits determined by molecular gut–content analysis (MGCA) in response to winter cover crops (rye and crimson clover) in a cotton agroecosystem. Predators were collected from replicated 1-ha experimental field plots during each major stage of crop development in 2017 and 2018, and MGCA was used to estimate predator roles and responses to cover crop treatments. Cotton planted into a rye cover crop residue promoted unique predator communities in the early and mid-season as compared to no-cover fields. Correspondingly, we observed dissimilar prey consumption among cover crop treatments. Winter cover crops led to an increase in consumption of alternative prey and incidental pests by natural enemies on seedling cotton and encouraged high predator diversity that aligns temporally with potential early-season pest outbreaks. Therefore, cover crops commonly employed for soil health and erosion benefits also contribute to pest management by providing habitat and alternative prey resources that boost early-season predatory arthropod communities.
  [Bowers, C., Toews, M.D. and Schmidt, J.M. Ecosphere, 12(7), p.e03635.]
- (Nano)microplastics promote the propagation of antibiotic resistance genes in landfill leachate
  Municipal landfill leachate is a huge reservoir of (nano)microplastics (N/MPs) and antibiotic resistance genes (ARGs). N/MPs have a proven ability to affect the growth of bacteria and composition of bacterial communities, which may further influence the spread of ARGs in the environment. To extrapolate the interactions between these two emerging contaminants, we investigated the variations of the ARG levels in leachate with exposures to different sizes of N/MPs. The results showed that ARGs were enriched in the N/MPs-exposed groups, especially in the 200–500 nm MP group. Notably, the enrichment became more pronounced in the long-term exposure samples than the short-term ones. Together with this process, the total abundance of bacteria, as well as the potential ARG-carrying bacteria, also increased in the N/MP-exposed groups, and the long-term N/MP exposure led more bacteria genera, such as Pseudomonas, Syntrophomonas, and Desulfotomaculum, to become closely associated with ARG variations. Meanwhile, the production of reactive oxygen species (ROS) induced by exposure to the 50–100 nm NPs and the 200–500 nm MPs was observed to increase bacterial membrane permeability, which might result in more bacteria becoming potential receptors of ARGs via the intra-bacterial community transfer of mobile genetic elements. Overall, the current study demonstrated that the presence of N/MPs in leachate promoted the propagation of ARGs due to their impacts on the bacterial community and cellular membrane permeability. These findings have important implications for understanding the environmental risks of the combined pollution of N/MPs and ARGs.
  [Shi, J. et al. (2020) (Nano)microplastics promote the propagation of antibiotic resistance genes in landfill leachate, Environmental Science: Nano. Available at: https://www.researchgate.net/publication/346720300_Nanomicroplastics_promote_the_propagation_of_antibiotic_resistance_genes_in_landfill_leachate. ]
- A review of the pesticide MCPA in the land-water environment and emerging research needs
  Due to its high solubility and poor adsorption to the soil matrix, the post-emergence herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) is susceptible to transport into surface and groundwater bodies, where it can result in compromised water quality and breaches of legislative standards. However, there is still poor understanding of catchment scale dynamics and transport, particularly across heterogeneous hydrogeological settings. While it is known that MCPA degrades under aerobic conditions, negligible breakdown can occur in anaerobic environments, potentially creating a legacy in saturated soils. Fast runoff pathways post application are likely transport routes, but the relative contribution from the mobilization of legacy MCPA from anaerobic zones has yet to be quantified, making the delineation of MCPA sources encountered during monitoring programs challenging. While ecotoxicological effects have been examined, little is known about the interaction of MCPA (and its degradation products) with other pesticides, with nutrients or with colloids, and how this combines with environmental conditions to contribute to multiple stressor effects. We examine the state of MCPA knowledge, using case study examples from Ireland, and consider the implications of its widespread detection in waterbodies and drinking water supplies. Research themes required to ensure the sustainable and safe use of MCPA in an evolving agricultural, social and political landscape are identified here. These include the need to identify mitigation measures and/or alternative treatments, to gain insights into the conditions governing mobilization and attenuation, to map pathways of migration and to identify direct, synergistic and antagonistic ecotoxicological effects.
  [Morton, P. et al. (2020) A review of the pesticide MCPA in the land‐water environment and emerging research needs, WIREs Water. Available at: https://wires.onlinelibrary.wiley.com/doi/full/10.1002/wat2.1402. ]
- Long-term effects of neonicotinoid insecticides on ants
  The widespread prophylactic usage of neonicotinoid insecticides has a clear impact on non-target organisms. However, the possible effects of long-term exposure on soil-dwelling organisms are still poorly understood especially for social insects with long-living queens. Here, we show that effects of chronic exposure to the neonicotinoid thiamethoxam on black garden ant colonies, Lasius niger, become visible before the second overwintering. Queens and workers differed in the residue-ratio of thiamethoxam to its metabolite clothianidin, suggesting that queens may have a superior detoxification system. Even though thiamethoxam did not affect queen mortality, neonicotinoid-exposed colonies showed a reduced number of workers and larvae indicating a trade-off between detoxification and fertility. Since colony size is a key for fitness, our data suggest long-term impacts of neonicotinoids on these organisms. This should be accounted for in future environmental and ecological risk assessments of neonicotinoid applications to prevent irreparable damages to ecosystems.
  [Schläppi, D., Kettler, N., Straub, L., Glauser, G. and Neumann, P., 2020. Communications biology, 3(1), pp.1-9.]
- Mobility, Degradation, and Uptake of Indaziflam under Greenhouse Conditions
  The objectives of this study were to evaluate the leaching, degradation, uptake, and mass balance of indaziflam, as well as its potential to produce phytotoxicity effects on young pecan trees. Pecan trees were planted in pots with homogeneous porous media (sandy loam soil), preferential flow channels open to the soil surface, and shallow tillage at the soil surface. Pots were treated with indaziflam at two application rates of 25 and 50 g a.i./ha in 2014 and 2015. Each pecan tree was irrigated with 7 L of water every 2 weeks during the growing season. An irrigation volume of 2 L was used to maximize indaziflam retention time in the soil from Dec. 2015 until the end of the trees’ dormant stage. In 2014, leachate samples were collected after each irrigation for quantifying indaziflam mobility. Soil samples were collected at depths of 0 to 12 and 12 to 24 cm after 45, 90, and 135 days of indaziflam application, and leaf samples were collected at the end of the growing season to quantify mobility and uptake. Indaziflam was detected in leachate samples, and the leaf indaziflam content increased with increasing application rate. Indaziflam and its breakdown products were detected at both sampling depths. Mass recovery and half-life values for indaziflam in the soil ranged from 38% to 68% and 63 to 99 days, respectively. No phytotoxicity effects were observed from increasing application rate and retention time of indaziflam in the soil. Most of the applied indaziflam was retained in the soil at shallow depth.
  [González-Delgado, A.M. and Shukla, M.K. (2020) Mobility, degradation, and uptake of Indaziflam under greenhouse conditions, HortScience. Available at: https://journals.ashs.org/hortsci/view/journals/hortsci/55/8/article-p1216.xml. ]
- The impact and toxicity of glyphosate and glyphosate-based herbicides on health and immunity
  Glyphosate, or N-phosphomethyl(glycine), is an organophosphorus compound and a competitive inhibitor of the shikimate pathway that allows aromatic amino acid biosynthesis in plants and microorganisms. Its utilization in broad-spectrum herbicides, such as RoundUp®, has continued to increase since 1974; glyphosate, as well as its primary metabolite aminomethylphosphonic acid, is measured in soils, water, plants, animals and food. In humans, glyphosate is detected in blood and urine, especially in exposed workers, and is excreted within a few days. It has long been regarded as harmless in animals, but growing literature has reported health risks associated with glyphosate and glyphosate-based herbicides. In 2017, the International Agency for Research on Cancer (IARC) classified glyphosate as “probably carcinogenic” in humans. However, other national agencies did not tighten their glyphosate restrictions and even prolonged authorizations of its use. There are also discrepancies between countries’ authorized levels, demonstrating an absence of a clear consensus on glyphosate to date. This review details the effects of glyphosate and glyphosate-based herbicides on fish and mammal health, focusing on the immune system. Increasing evidence shows that glyphosate and glyphosate-based herbicides exhibit cytotoxic and genotoxic effects, increase oxidative stress, disrupt the estrogen pathway, impair some cerebral functions, and allegedly correlate with some cancers. Glyphosate effects on the immune system appear to alter the complement cascade, phagocytic function, and lymphocyte responses, and increase the production of pro-inflammatory cytokines in fish. In mammals, including humans, glyphosate mainly has cytotoxic and genotoxic effects, causes inflammation, and affects lymphocyte functions and the interactions between microorganisms and the immune system. Importantly, even as many outcomes are still being debated, evidence points to a need for more studies to better decipher the risks from glyphosate and better regulation of its global utilization.
  [Peillex, C. and Pelletier, M. (2020) The impact and toxicity of glyphosate and glyphosate-based herbicides on health and immunity, Journal of Immunotoxicology. Available at: https://www.tandfonline.com/doi/full/10.1080/1547691X.2020.1804492.]
- Microplastics Can Change Soil Properties and Affect Plant Performance
  Microplastics can affect biophysical properties of the soil. However, little is known about the cascade of events in fundamental levels of terrestrial ecosystems, i.e., starting with the changes in soil abiotic properties and propagating across the various components of soil–plant interactions, including soil microbial communities and plant traits. We investigated here the effects of six different microplastics (polyester fibers, polyamide beads, and four fragment types: polyethylene, polyester terephthalate, polypropylene, and polystyrene) on a broad suite of proxies for soil health and performance of spring onion (Allium fistulosum). Significant changes were observed in plant biomass, tissue elemental composition, root traits, and soil microbial activities. These plant and soil responses to microplastic exposure were used to propose a causal model for the mechanism of the effects. Impacts were dependent on particle type, i.e., microplastics with a shape similar to other natural soil particles elicited smaller differences from control. Changes in soil structure and water dynamics may explain the observed results in which polyester fibers and polyamide beads triggered the most pronounced impacts on plant traits and function. The findings reported here imply that the pervasive microplastic contamination in soil may have consequences for plant performance and thus for agroecosystems and terrestrial biodiversity.
  [Machado, A. et al. (2019) Microplastics can change soil properties and affect plant performance, Environmental Science & Technology. Available at: https://pubs.acs.org/doi/10.1021/acs.est.9b01339. ]
- Occurrence and Ecological Impacts of Microplastics in Soil Systems: A Review
  Microplastics, as a group of emerging contaminants, are receiving growing attention. During the last decade, their occurrence and toxicity in aquatic ecosystems have been intensively studied and reviewed, but less attention has been paid on soil ecosystems. Given the importance of soil ecosystems and the call for increasing research on soil from scientific communities, it is predicted that relevant studies will boom in the following years. The present review intends to provide a comprehensive overview of current knowledge on microplastic pollution in soil environments. We critically summarize the source, contamination level and fate of microplastics in (industrial and arable) soils. Then, we thoroughly describe what effects have been observed on soil microbes, animals and plants, and analyze what insights we can get from available information. Finally, we identify knowledge gaps that need to be filled and give suggestions for future research.
  [Zhu, F. et al. (2019) Occurrence and ecological impacts of microplastics in soil systems: A Review, Bull Environ Contam Toxicol. Available at: https://pubmed.ncbi.nlm.nih.gov/31069405/. ]
- Uptake and distribution of fluopyram and tebuconazole residues in tomato and bell pepper plant tissues
  The present study describes the uptake and distribution of fungicides, fluopyram, and tebuconazole in tomato and bell pepper plant tissues from the soil drench application of their combination product fluopyram17.7% + tebuconazole 17.7%. For extraction and cleanup of fluopyram, its metabolite fluopyram benzamide, and tebuconazole samples, the QuEChERS method was used in conjunction with LC-MS/MS. The limit of detection (LOD) and limit of quantification (LOQ) of the method determined were 1.5 μg kg−1 and 0.005 mg kg−1, respectively, and recoveries of all analytes from sample matrices remained within the acceptable range of 70–120%. Rapid uptake of the fungicides by tomato and bell pepper plants was observed from the first day onwards. In the tomato plant, the major part of the fungicides accumulated in the roots, whereas in bell pepper plant, it accumulated both in the roots and in the leaves. Accumulation of fluopyram and tebuconazole residues was lowest in tomato and bell pepper fruits which were much below their respective maximum residue limits (MRLs). The highest residue concentration of fluopyram and tebuconazole in tomato fruits was 0.060 and 0.009 mg kg−1; the corresponding values in bell pepper fruits were 0.080 and 0.013 mg kg−1. In field soil, fluopyram residues were 3.18–3.570 mg kg−1 initially which dissipated at the half-life of 36 days. Tebuconazole concentration was 1.57–1.892 mg kg−1 initially, and it dissipated at the half-life of 44.5–49.5 days. The major metabolite of fluopyram, fluopyram benzamide, was detected in plant tissues as well as in soil, and remained within 12% of the parent compound. The results of the study indicated that fluopyram and tebuconazole are less likely of entry into food chain through intake of tomato and bell pepper fruits if these crops are grown on soil contaminated with these fungicides.
  [Matadha, N.Y. et al. (2019) Uptake and distribution of fluopyram and tebuconazole residues in tomato and bell pepper plant tissues, Environmental Science and Pollution Research. Available at: https://link.springer.com/article/10.1007/s11356-018-04071-4. ]
- Microplastics in soils: Analytical methods, pollution characteristics and ecological risks
  Microplastics are emerging persistent contaminants of increasing concern. Although microplastics have been extensively detected in aquatic environments, their occurrence in soil ecosystems remains largely unexplored. This review focused on recent progress in analytical methods, pollution characteristics and ecological effects of microplastics in soils. In spite of the presence of microplastics in soils, no standardized methods are available for the quantification. Uniform protocols including microplastic extraction and identification are urgently needed to develop. In soil environments, main sources of microplastics include mulching film, sludge, wastewater irrigation and atmospheric deposition. The fate of microplastics is closely related to soil physio-chemistry and biota. Existing evidence shows that microplastics can influence soil biota at different trophic levels, and even threaten human health through food chains. Therefore, further research is needed to fully reveal the fate and ecological risks of microplastics in soils; and necessary action is required to control microplastic pollution in terrestrial ecosystems.
  [He, D. et al. (2018) Microplastics in soils: Analytical methods, pollution characteristics and ecological risks, TrAC Trends in Analytical Chemistry. Available at: https://www.sciencedirect.com/science/article/pii/S0165993618304102?ref=pdf_download&fr=RR-7&rr=87d9ad93cbbf2f24. ]
- Sub-micron level investigation reveals the inaccessibility of stabilized carbon in soil microaggregates
  Direct evidence-based approaches are vital to evaluating newly proposed theories on the persistence of soil organic carbon and establishing the contributions of abiotic and biotic controls. Our primary goal was to directly identify the mechanisms of organic carbon stabilization in native-state, free soil microaggregates without disrupting the aggregate microstructure using scanning transmission x-ray microscopy coupled with near edge x-ray absorption fine structure spectroscopy (STXM-NEXAFS). The influence of soil management practices on microaggregate associated-carbon was also assessed. Free, stable soil microaggregates were collected from a tropical agro-ecosystem in Cruz Alta, Brazil. The long-term experimental plots (>25 years) comparing two tillage systems: no-till and till with a complex crop rotation. Based on simultaneously collected multi-elemental associations and speciation, STXM-NEXAFS successfully provided submicron level information on organo-mineral associations. Simple organic carbon sources were found preserved within microaggregates; some still possessing original morphology, suggesting that their stabilization was not entirely governed by the substrate chemistry. Bulk analysis showed higher and younger organic carbon in microaggregates from no-till systems than tilled systems. These results provide direct submicron level evidence that the surrounding environment is involved in stabilizing organic carbon, thus favoring newly proposed concepts on the persistence of soil organic carbon.
  [Pitumpe Arachchige, P.S. et al. (2018) Sub-micron level investigation reveals the inaccessibility of stabilized carbon in soil microaggregates, Scientific Reports. Available at: https://www.nature.com/articles/s41598-018-34981-9. ]
- Healthy soils: a prerequisite for sustainable food security
  Soil health constitutes the foundation for the production of healthy food and thus contributes to local and global food security. Recent findings indicate that there will need to be a 60 % increase in global food production and associated ecosystem services by 2050. However, one-third of global soils are currently facing moderate to severe degradation through soil erosion, nutrient depletion, salinity, sealing and contamination. Evidence-based decisions and soil information are crucial for achieving sustainable soil management at all levels. In 2012, the Food and Agriculture Organization (FAO) of the United Nations established the Global Soil Partnership to highlight effective and concerted actions against soil degradation and to advocate healthy soils for a food secure world.
  [Rojas, R.V. et al. (2016) Healthy soils: A prerequisite for Sustainable Food Security - Environmental Earth Sciences, Soil Physics and Land Management. Available at: https://link.springer.com/article/10.1007/s12665-015-5099-7. ]
- An overview of the environmental risks posed by neonicotinoid insecticides
  Neonicotinoids are now the most widely used insecticides in the world. They act systemically, travelling through plant tissues and protecting all parts of the crop, and are widely applied as seed dressings. As neurotoxins with high toxicity to most arthropods, they provide effective pest control and have numerous uses in arable farming and horticulture. However, the prophylactic use of broad-spectrum pesticides goes against the long-established principles of integrated pest management (IPM), leading to environmental concerns. It has recently emerged that neonicotinoids can persist and accumulate in soils. They are water soluble and prone to leaching into waterways. Being systemic, they are found in nectar and pollen of treated crops. Reported levels in soils, waterways, field margin plants and floral resources overlap substantially with concentrations that are sufficient to control pests in crops, and commonly exceed the LC50 (the concentration which kills 50% of individuals) for beneficial organisms. Concentrations in nectar and pollen in crops are sufficient to impact substantially on colony reproduction in bumblebees. Although vertebrates are less susceptible than arthropods, consumption of small numbers of dressed seeds offers a route to direct mortality in birds and mammals. Synthesis and applications. Major knowledge gaps remain, but current use of neonicotinoids is likely to be impacting on a broad range of non-target taxa including pollinators and soil and aquatic invertebrates and hence threatens a range of ecosystem services.
  [Goulson, D. (2013) An overview of the environmental risks posed by neonicotinoid insecticides, Journal of Applied Ecology. Available at: https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2664.12111. ]
- Snails as indicators of pesticide drift, deposit, transfer and effects in the vineyard
  This paper presents a field-study of real pesticide application conditions in a vineyard. The objective was to measure the exposure, the transfer and the effects of pesticides on a non-target soil invertebrate, the land snail Helix aspersa. There was no drift of the herbicides (glyphosate and glufosinate) whereas the fungicides (cymoxanil, folpet, tebuconazole and pyraclostrobin) were detected up to 20 m from the treated area. For folpet and particularly tebuconazole, spray deposits on soil (corresponding to losses for the intended target i.e. the vine leaves) were high (41.1% and 88.8% loss of applied dose, respectively). For herbicides, the target was the soil and losses (percentage of compounds which did not reach the soil) were of 22% for glufosinate and 52% for glyphosate. In the study plot, glyphosate was transferred to and accumulated in snail tissues (4 mg kg−1 dry weight, dw), as was its metabolite AMPA (8 mg kg−1 dw) which could be in relation with the reduced growth observed in snails. No effects on snail survival or growth were found after exposure to the other organic compounds or to copper and sulphur-fungicides, although transfer of tebuconazole, pyraclostrobin and copper occurred. This study brings original field data on the fate of pesticides in a vineyard agro-ecosystem under real conditions of application and shows that transfer and effects of pesticides to a non-target organism occurred.
  [Druart, C. et al. (2011) Snails as indicators of pesticide drift, deposit, transfer and effects in the vineyard, Science of The Total Environment. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0048969711007224?via%3Dihub. ]
- Organic Pollutants in Areas Impacted by Flooding in 2002: A 4-Year Survey
  This paper summarizes a 4-year survey focused on polycyclic aromatic hydrocarbons (PAHs) and halogenated persistent organic pollutants (POPs) in river sediments, soil and crops collected in the locality impacted by catastrophic floods that occurred in the western part of Bohemia in August 2002. In spite of relatively high levels of polychlorinated biphenyls (PCBs) in river sediments, the increase of these POPs in flooded arable soil was not significant. On the other hand, remarkably higher levels of PAHs and dichlorodiphenyl trichloroethane (DDTs) were found as compared to those in reference soil samples. Regardless of this increased soil pollution, no measurable elevated concentrations of POPs occurred in the wheat grown in this area.
  [Pulkrabová, J. et al. (2008) Organic Pollutants in Areas Impacted by Flooding in 2002: A 4-Year Survey, Bulletin of Environmental Contamination and Toxicology. Available at: https://link.springer.com/article/10.1007/s00128-008-9486-6. ]
- Soil health and global sustainability: translating science into practice
  Interest in the quality and health of soil has been stimulated by recent awareness that soil is vital to both production of food and fiber and global ecosystems function. Soil health, or quality, can be broadly defined as the capacity of a living soil to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health. Soil quality and health change over time due to natural events or human impacts. They are enhanced by management and land-use decisions that weigh the multiple functions of soil and are impaired by decisions which focus only on single functions, such as crop productivity. Criteria for indicators of soil quality and health relate mainly to their utility in defining ecosystem processes and in integrating physical, chemical, and biological properties; their sensitivity to management and climatic variations; and their accessibility and utility to agricultural specialists, producers, conservationists, and policy makers. Although soils have an inherent quality as related to their physical, chemical, and biological properties within the constraints set by climate and ecosystems, the ultimate determinant of soil quality and health is the land manager. As such, the assessment of soil quality or health, and direction of change with time, is the primary indicator of sustainable management. Scientists can make a significant contribution to sustainable land management by translating scientific knowledge and information on soil function into practical tools and approaches by which land managers can assess the sustainability of their management practices. The first steps, however, in our communal journey towards sustainable land management must be the identification of our final destination (sustainability goals), the strategies or course by which we will get there, and the indicators (benchmarks) that we are proceeding in the right direction. We too often rush to raise the sails of our ‘technological’ ship to catch the wind, before knowing from where it comes or in properly defining our destination, charting our course, and setting the rudder of our ship. Examples are given of approaches for assessing soil quality and health to define the sustainability of land management practices and to ‘translate our science into practice’.
  [Duran, J. (2002) Soil Health and Global Sustainability: Translating Science Into Practice, Agriculture, Ecosystems & Environment. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0167880901002468. ]
- Soil health and sustainability: managing the biotic component of soil quality
  Soil health is the capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health. Anthropogenic reductions in soil health, and of individual components of soil quality, are a pressing ecological concern. A conference entitled ‘Soil Health: Managing the Biological Component of Soil Quality’ was held was held in the USA in November 1998 to help increase awareness of the importance and utility of soil organisms as indicators of soil quality and determinants of soil health. To evaluate sustainability of agricultural practices, assessment of soil health using various indicators of soil quality is needed. Soil organism and biotic parameters (e.g. abundance, diversity, food web structure, or community stability) meet most of the five criteria for useful indicators of soil quality. Soil organisms respond sensitively to land management practices and climate. They are well correlated with beneficial soil and ecosystem functions including water storage, decomposition and nutrient cycling, detoxification of toxicants, and suppression of noxious and pathogenic organisms. Soil organisms also illustrate the chain of cause and effect that links land management decisions to ultimate productivity and health of plants and animals. Indicators must be comprehensible and useful to land managers, who are the ultimate stewards of soil quality and soil health. Visible organisms such as earthworms, insects, and molds have historically met this criterion. Finally, indicators must be easy and inexpensive to measure, but the need for knowledge of taxonomy complicates the measurement of soil organisms. Several farmer-participatory programs for managing soil quality and health have incorporated abiotic and simple biotic indicators. The challenge for the future is to develop sustainable management systems which are the vanguard of soil health; soil quality indicators are merely a means towards this end.
  [Doran, J.W. and Zeiss, M.R. (2000) Soil Health and Sustainability: Managing the biotic component of Soil Quality, Applied Soil Ecology. Available at: https://digitalcommons.unl.edu/agronomyfacpub/15/.]

Soil Biota

Scientific Studies:

Abstract