“Many times during a drought, plants are not as much water stressed as they are nutrient stressed,” said USDA soil microbiologist Kris Nichols.
Cover crops feed a whole web of soil organisms…much more than mere crop residue. Those organisms seek carbon and they get it from live plants like corn.
Nichols said that the microbes, in exchange for carbon, give up nutrients and water which they get from the soil.
Mycorrhizal fungi are an example Nichols uses to explain the value added that microbiology brings to crops. The little critters are threadlike, much smaller in width than plant roots, and have more access to more soil than plants.
Cover crops like annual ryegrass are conducive to production of healthy mycorrhizae population and create a symbiotic relationship helping the fungi, the soil and the plants. “Plants growing in soils rich with mycorrhizae take advantage of the fungi to help them obtain nutrients from the soil,” she added.
“They accomplish this using much less water, as well,” Nelson continued. The soil structure, rich with microorganisms, is more conducive to water retention, as she explains, “Organisms help form soil aggregates, which allows for better water absorption because there is more pore space in the soil for water as well as an exchange of gas.”