09
Aug
Study Shows Value of Soil Microbiome, Nurtured in Organic Farming, Harmed by Chemical-Intensive Ag
(Beyond Pesticides, August 9, 2024)​​ A study in the journal Biology and Fertility of Soils has confirmed once again that organic agriculture contributes significantly to soil health, improving ecological functions that are harmed by conventional, chemical-intensive farming practices. Organic soil amendments (fertilizers) that feed soil organisms increase beneficial protistan predators and support sustainable predator-prey relationships within the soil microbiome. [‘Protist’ is a catch-all term that describes ancient lineages of eukaryotes—organisms with a nucleus—that are neither a true plant, animal, or fungus.] The study shows that organic farming creates a healthy ecosystem able to support a balance of life forms in the soil. Moreover, the study finds that the use of chemical fertilizers for agricultural management disrupt the stable biological relationship between protistan predators and their bacterial prey in soils, adding to the argument for transitioning away from conventional systems that lean on toxic inputs. Â
Healthy soil contains millions of living species that form the microbiome. Most of the biodiversity in soil consists of bacteria and fungi, and their number and type are regulated partially by predatory protists and nematodes that feed on bacteria. Akin to the impact of predators keeping a herd of prey healthy by hunting the sick, protists keep the bacteria population healthy by removing the more inert microbes and releasing nutrients into the soil. In working together, these tiny organisms in organic land management systems determine the health of the soil for plant growth.
The authors indicate that they chose to examine protists because of the relative lack of studies regarding the effect of different fertilizers on the diversity and composition of soil protists, their importance to soil health, and their relative vulnerability to variations in agricultural practices. Compared with other microbial groups, researchers also cite evidence that protistan predators are more sensitive to the effects of petrochemical fertilizers. Fertilizers may cause changes in the diversity and taxonomic and functional compositions of soil protist communities.Â
The study researchers from China analyze the soil from organic and conventional agricultural systems—200 and 179 soil samples, respectively—where bacterial and protistan data was available. The analysis compares the diversity and functionality of microbial communities between the two systems and how differences in soil properties contribute to changes in microbial abundance and diversity. Researchers also analyze a case study—based on cucumber cultivation with either organic or chemical fertilizers for three years between 2014 and 2016—for differences in soil properties resulting from different fertilizer management practices that contribute to changes in the soil biome. The case study includes an analysis of soil pH, organic matter, total nitrogen, total phosphorus, total potassium, and available nitrogen, phosphorus, and potassium.
Researchers found that organic soils have more bacteria and thereby support more heterogeneous communities of bacteria and protists. By providing more nutrients via organic soil amendments, organic agricultural systems allow faster and more abundant bacteria growth, which in turn feeds more protists than conventional farming. Moreover, protistan predators may prey on plant pathogens, thereby enhancing plant health. They also contribute significantly to nutrient cycling in the soil ecosystem and free up nutrients that can be used for plant growth.
The idea of organic systems, growing out of the study of composting, started with respecting the health of the soil as a living ecosystem. As J.I. Rodale and the Rodale staff wrote in The Complete Book of Composting, “At the very foundation of good nutrition is the soil—soil that is fertile and alive, that is kept in shape to grow plants as nature meant them to be grown. The life and balance in this soil [are] maintained by returning to it those materials which hold and extend life in a natural cycle, and aid in replenishing the nutrients needed to produce healthy, life-supporting crops. Soils that lack vital plant nutrients cannot give these food values to what is grown in them.â€
In addition to supporting a healthy soil ecosystem, organic farming is necessary to stop and address the existential threat of global warming and the climate crisis. A study in the Journal of Cleaner Production in August 2023 concludes that “a one percent increase in total farmland results in a 0.13 percent increase in greenhouse gas emissions, while a one percent increase in organic cropland and pasture leads to a decrease in emissions by about 0.06 percent and 0.007 percent, respectively.â€Â Meanwhile, the 30% growth in emissions of nitrous  (N2O), a potent greenhouse gas, over the last four decades is mostly attributable to petrochemical nitrogen fertilizer use on cropland. Harmful nitrogen oxides (NOx, NO, NO2) increase public health risks for asthma and other respiratory illnesses through the creation of smog and acid rain.
While reducing the influx of dangerous nitrogen compounds into the atmosphere, organic systems additionally sequester significant amounts of carbon from the atmosphere. As previously reported by Beyond Pesticides, healthy soil can absorb and store 1,000 pounds of carbon per acre foot of soil annually under organic land management. This translates to roughly 3,500 pounds of carbon dioxide per acre drawn down from the air and sequestered into organic matter in soil. It is also noteworthy that the use of synthetic fertilizers undermines the carbon-capture ability of some kinds of terrain, such as salt marshes.
As Beyond Pesticides has repeatedly emphasized, serious health threats, biodiversity collapse, and the climate emergency are existential crises that undermine a livable future. The solution requires a meaningful holistic strategy that commits the nation to ending our fossil fuel-based economy and use of petroleum-based materials that release harmful levels of carbon and noxious gases into the environment. Just as there are proposals to end production of the combustion engine and move to electric vehicles, advocates must demand that agriculture—across the board and on an expedited schedule—shift to organic practices, whose standards are already codified in federal law with a proven and commercially viable track record.
A seemingly intractable problem remains: the vested economic interests in the petroleum and chemical industry are holding on to the status quo of a chemical-intensive pesticide treadmill. To address this challenge, Beyond Pesticides urgently calls for critically needed national grassroots collaboration to reframe the public debate and shift the needle of conversation towards holistic systems change via support for organic land management. A precautionary approach, embraced by organic principles, starts with the premise that we do not need toxic chemicals to achieve food productivity goals or beautiful landscapes.
Help affect a shift away from petrochemical pesticides and fertilizers and to safer organic land care practices through purchasing certified organic food whenever possible.  Please visit Beyond Pesticides’ Eating with a Conscience webpage to learn why eating organic foods is the right choice and how to eat organic on a budget. Consider supporting local organic farmers through farmers’ markets. And join Beyond Pesticides in fighting to protect the importance of organic integrity—earn why public engagement is needed to ensure the National Organic Standards Board upholds strict rules regulating organic agriculture.
Take action to change land care in homes, gardens, schools, and public parks, as well as agriculture. The focus on soil health is a basic principle in organic agriculture that directly applies to all land management, including organic lawn and landscape care. See Beyond Pesticides’ website to learn about lawns and landscapes, hazards, and safer alternatives to using lawn pesticides and please visit the Tools for Change page to learn how to organize your community to end pesticide use and adopt organic land care.
Beyond Pesticides, with the support of our generous sponsors and local activists, has launched the Parks for a Sustainable Future program in partnership with local communities nationwide to transition two demonstration sites to organic land management. The demonstration sites become the basis for broader changes as a model approach towards organic land care. Sign up to be a Parks Advocate today to let us know you’re willing to speak with local leaders about the importance of this program.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Sources:
Investigating protistan predators and bacteria within soil microbiomes in agricultural ecosystems under organic and chemical fertilizer applications, Biology and Fertility of Soils, July 20, 2024
Soil protists: An untapped microbial resource of agriculture and environmental importance, Pedosphere, February 22, 2022
Protist – an overview (chapter), Physiological and Molecular Plant Pathology, 2023
Synthetic Fertilizers Accelerate Climate Crisis; The Way We Feed People Conflicts with Stabilizing Climate, Beyond Pesticides, Daily News Blog, November 2020
Products Compatible with Organic Landscape Management, Beyond Pesticides, Pesticides and You, Spring 2017
Fertilizers Compatible with Organic Landscape Management, Beyond Pesticides, Pesticides and You, Fall 2017
