Soil health begins with understanding soil biota, according to Janice Thies, associate professor of soil biology at Cornell University. She presented the importance of the creatures that live in the soil during the recent Empire Farm Days.
âBiota provides ecosystem services, including benefits such as the breakdown of organic matter, nutrient release and cycling, nitrogen fixation, and mycorrhizal fungi,â Thies said.
She added that biota also suppresses disease and improves soil structure – the soil’s ability to sustain itself under the impact of rainfall. This is an important advantage, as it promotes filtration and storage of water. Biota also consumes greenhouse gases in the air and reduces greenhouse gases emitted.
âFarming systems are under pressure on how to reduce greenhouse gas production,â Thies said. “They are a genetic reservoir.”
But biota also has a few caveats. They can immobilize nutrients and cause disease, for example.
âEnergy is essential for microbial survival and functioning in the soil environment,â Thies said.
Major factors limiting biological activity include energy supply, such as light penetration to plants and substrate quality and availability for soil organisms, as well as functioning as a cellular carbon source, such as carbon dioxide for plants and organic carbon for most soil organisms.
âFor some organisms, they can fix their own carbon dioxide,â Thies said.
Soil organisms can aid in nutrient cycling, soil aggregation, plant protection, plant productivity, detoxification, and organic matter formation. In the soil, nematodes, fungi and bacteria all have positive and negative functions affecting plants.
âWe have parasitic nematodes that are useless,â Thies said.
These are the nematodes that farmers should strive to control. But beneficial nematodes can control the proliferation of harmful agents and break down organic matter.
Plants and the soil microbiome share “a very nice symbiotic relationship,” Thies said.
Plants absorb carbon dioxide and release food for soil organisms. Soil organisms provide enzymes, minerals, antibiotics, growth regulators and hormones to nourish plants.
Bacteria break down organic matter, displace nutrients, and control pathogens. But rogue bacteria can also cause plant diseases.
âThe first thing you need to do is flip the floor,â Thies said. âA lot of things we rely on include inoculants and cultural control. “
The first includes nitrogen fixing bacteria, phosphorus solubilization, microbial soups, compost teas, and signaling molecules alone. The latter includes adding organic matter, reducing toxins, maintaining plants in the system with cover crops, oxygenating the soil, and improving drainage.
âAll of these systems are controlled by bacteria,â Thies said. âWe have decades of success with the legume / rhizobium symbiosis. We have been inoculating plants since the early 1900s. â
To promote the overall health of the soils, Thies said farmers have many tools at their disposal, such as using compost to feed soil organisms.
âThey need to eat so they can work for you,â Thies said.
She added that fungi also play a role in soil health, as they break down organic matter, mobilize phosphorus, control pathogens, promote plant growth, control insects, and aggregate and stabilize the soil.
âThese are all very important functions,â Thies said. âTry to reduce toxins like fungicides. For the most part, mushrooms are your friends.
It is also helpful to reduce tillage and avoid bare fallow fields.
While many beneficial agents in soil are tiny, larger ones like earthworms, sow bugs, mites and dung beetles also help enrich the soil by simulating microbial activity, mixing the soil, increasing water filtration and breaking down organic matter. Reducing tillage and chemicals while increasing organic matter can encourage the growth of these soil auxiliaries.
âWe need to think about how to promote the benefits and reduce the impact of those who are not,â Thies said. “We have to think about the exchange of gas and water.”
At Cornell, Thies focuses her study on soil ecology as an indicator of biological soil quality, remediation of degraded soils and sustainable soil management.