Grow Life in the Soil
Soil is filled with living, breathing, hardworking creatures – it’s a natural commodity more important than any cash crop. When soil is alive, it’s teaming with macro- and microorganisms, ranging the gamut from highly visible beetles and worms to microscopic viruses, bacteria, and fungi. Each of these soil citizens provides a service to the healthful functioning of the broader community.
Having lots of healthy and diverse organisms in the soil creates a self-sufficient cropping system that becomes less dependent upon synthetic fertilizers and pesticides.
The system itself produces fertility for robust plant growth, resistance to pests, and water-stable soil aggregates that enhance soil porosity to permit rapid water infiltration and to resist erosion.
In a nutshell, such a system produces resilient crops. In today’s uncertainty of climate, the need for plant resilience is growing more urgent by the day.
“The need to think about and work toward soil health is becoming extreme,” says Kris Nichols, a soil scientist-consultant from Kutztown, Pennsylvania. “Plants need resilience in order to withstand stressors such as adverse weather. One thing that you can count on is a continuing increase in the uncertainty and variability of climate.
“During the span of just one week here in Pennsylvania last winter, we had historic lows and historic highs in temperature,” she says. “We had a swing in temperature of 70°F. That doesn’t make any sense. Yet, it’s happened multiple times. How does a plant respond to such variability in conditions?
“We need a production system that is resilient,” she says. “A healthy soil that is alive with organisms keeps the system resilient. It does that by promoting diversity of life in the soil and above ground.”
Along with the growing need for resilience in cropping systems, there is a need for the kind of stable soil structure that resists wind and water erosion.
“We lose nearly 2 billion metric tons of topsoil annually in the U.S.,” says Nichols. “Most of that ends up in lakes, rivers, and estuaries. In the Gulf region, for instance, dredging is needed to remove the soil in order to keep shipping lanes open. Much of it is piled in that area, clogging the estuaries and exacerbating drainage problems.”
Eroding topsoil typically carries nitrates and phosphates from synthetic fertilizers with it, notes Nichols. These nitrates and phosphates end up in ground and surface waters, creating conditions such as the Dead Zone in the Gulf of Mexico.
“In some communities now in places such as the Midwest, it’s hard to get good drinking water without having to do costly filtration,” she says.
Limited supplies of phosphorus (P) fertilizers are yet another reason to build communities of healthy soil critters that can meet the plants’ need for P by extracting it from the soil and delivering it to plants.
“Globally, we’re running out of phosphorus fertilizer,” says Nichols. “Phosphorus fertilizer is mined and shipped into this country. A supply of about 20 to 30 years is about all we have left. Then we’ll have to figure out a different way to get it. Furthermore, when we apply it, much of it is wasted because, if it is not lost via erosion, it becomes readily unavailable in soil and can only be made available again by soil biology.”
These symbiotic relationships between plants and soil organisms permit natural pathways to fertility, disease resistance, soil stability, and whole-system resilience to weather variabilities.
All this while sidestepping much of the need for intervention with synthetic inputs.
When functioning in a healthful, whole-system framework, these relationships between plants and soil organisms, says Nichols, exist in an “elegantly complex” balance grounded in simple processes.
“We need to think about caring for the soil in the same manner that we take care of our own bodies,” she says.
With that in mind, following are the three cornerstones she suggests putting in place to grow life in the soil.
1. A healthy diet. “Carbon is the building block for every cell and every molecule for nearly all life on planet Earth,” she says. “Soil needs an influx of carbon through the process of photosynthesis occurring in living plants. It’s important to keep living plants growing in the soil.”
Diversity of diet is critical, too. “Feeding the soil a continuous diet of corn or wheat crops provides a lot of carbon, but it won’t be that healthy,” says Nichols. “Like us, the soil needs carbon in the form of protein or more complex carbohydrates. That’s why it’s important to have legumes and oilseeds in the system.
“All the different crops and crop types provide different compounds and different concentrations of these compounds for the soil life to eat,” she says. “Different consortia of different organisms consume different root exudates and crop residue from different plants.”
Growing diverse crops, cover crops, and perennials provides the soil life with the diverse diet needed to thrive and increase in population. Increasing diversity of cover crops can compensate for decreased diversity in cash crops.
2. Plenty of exercise. Providing the soil critters with work gives opportunity for exercise. “Their work involves breaking down and releasing nutrients in organic matter and minerals in the soil,” says Nichols. “In this process, they provide water and nutrients to the plants. Like us, they need a little bit of stress in order to best manage their food.”
A supply-and-demand payment system exists between plants and soil life. The application of synthetic fertilizers interferes with this delicate balance.
“Applying fertilizers outsources the work of the soil organisms,” says Nichols. “They buy carbon from the plant by giving the plant something.”
Outsourcing of their work happens, she says, when applications of synthetic fertilizers cause a lockdown in the plants’ natural mechanisms to work with soil organisms.
Thus, the soil organisms are bypassed, preventing them from having enough food to live on.
One example of this is roots that won’t allow arbuscular mycorrhizal fungi to colonize them.
3. A stable home. The soil organisms engineer for themselves homes in the soil known as soil aggregates. “The aggregates are like microbial villages, giving the fungi and bacteria a safe place to live,” says Nichols. "Tillage breaks apart the aggregates. It’s like taking a wrecking ball or a bomb and blowing up the village.”
The displaced organisms become more vulnerable to predatory organisms. “They were safe in their village, but now they’re exposed to larger organisms that eat them,” she says.
This predator/prey relationship is always going on in the soil, but the loss of soil aggregates permits an unhealthful balance of species.
Reducing tillage preserves habitat for the soil life, as does keeping the soil covered by residue or mulch.
“Even the impact of raindrops hitting the soil surface can blow up aggregates,” says Nichols.
Over the long term, growing life in the soil offers the priceless benefit of building a production system that is more resilient to wide swings in weather. Economic resilience could come hand in hand with healthier soil.
“You could expect to reduce costs, which could improve the bottom line,” says Nichols. “With a more resilient system, you could also expect to reduce year-to-year fluctuations in income.”
Kris Nichols at 701/426-1208 or Kris@kris-systems.com