To restore our soils, feed the microbes
Our soils are in trouble. Over the past century, we’ve abused them with plowing, tilling and too much fertilizer.
What many think of as “just dirt” is actually an incredibly complex mixture of rock-derived minerals, plant-derived organic matter, dissolved nutrients, gases and a rich food web of interacting organisms.
By plowing and overtilling, we have increased erosion on agricultural fields by 10 to 100 times natural rates. Over just the last several decades, we may have lost about half of the topsoil that natural processes produced over thousands of years in the U.S. corn belt.
Topsoil is rich in soil organic matter – dark spongy material formed from decomposed plant and animal tissue. Soil organic matter is critically important: It helps soils hold onto water and nutrients and supports soil microbes that recycle nutrients. Loss of soil organic matter has made many farms increasingly reliant on fertilizers, pesticides and herbicides.
Much recent research has focused on adding organic material back to soils to restore them. This is an important strategy, but I believe we also should aim to enhance the microbes that are responsible for soil formation. I was part of a research team that demonstrated in a 2015 study that adding efficient microbes to soils can enhance the percentage of plant carbon that is transformed into soil. New research suggests that by fostering an efficient and active soil microbiome, we can accelerate soil regeneration far beyond typical rates seen in nature.
Natural soils are thriving with life. They contain an incredible diversity of microscopic bacteria, fungi, viruses and other organisms. A single handful of soil can contain tens of thousands of different species.
These microbes interact closely with each other, forming complex networks. They communicate with chemical signals. They work together to break down complex organic materials, including dead plants and animals. They often work in teams to complete biochemical processes, such as transforming nitrogen from an inert gas to plant-usable forms, and recycling it from dead plant materials back into dissolved forms.