“The rejuvenation of your soil does not start with the implementation of principles but rather with the commitment to understanding the ecological functions,” Adam Daugherty says. Daugherty, the Natural Resources Conservation Service (NRCS) District Conservationist for Coffee County, Tenn., says the common denominator of no-till and cover crop success stories goes deeper than just the practices farmers implement.
The foundation to this understanding is seeing soil as something living that needs food, moisture and a static address in order to thrive.
Capturing Energy
“The symptom is our soils are starved,” Daugherty says. “The problem is the food to energy source shines 365 days a year, but we're not capturing it.”
Symptoms of surface and vertical erosion and low infiltration point to the problem of exposed soil. Compaction often reveals a lack of soil aggregates. A lack of biological diversity occurs in continuous monocultures.
“We're the key because the sun, plants and soil are going to be what they are, but us as humans have a lot of influence,” Daugherty says.
Changing the life in the soil helps address the other symptoms farmers try to address because they are all biologically regulated. Making those changes leads to a more resilient soil that can better support a crop through wet, dry or ideal years. Building a resilient soil requires a farmer to consider what the soil itself desires, not just to consider what the crop desires.
“What the soil desires is to get its life back in order to a stable carbon-to-nitrogen ratio in its system because these folks [soil microbes] that live down there, they optimize and they function best at a certain carbon-to-nitrogen ratio in the soil system,” Daugherty says.
When the carbon-to-nitrogen ratio is stable, the soil can support large and resilient water cycles and soil food webs. Additionally, the soil can better supply nutrients to the plants so less synthetic fertilizer needs to be applied.
All these benefits and changes are driven by the soil capturing energy through plants photosynthesizing which illustrates the need to have a living plant on the soil as often as possible. Soil between crop roots gets left behind, and the bacteria living there starve during the growing season. When the bacteria don’t have enough liquid sugar from photosynthesis to eat, they start to eat the soil aggregates.
“We start losing our aggregation, start losing our infiltration, start losing our airflow. Even without any mechanical disturbance, we made a disturbance to the available food in the system and it has an effect,” Daugherty says.
In the absence of plants, more complex carbon food provides another food source. However, many of the carbon food sources are too complex for the soil bacteria to eat.
Four Key Principles
Keep the soil covered: Covering the soil serves as a preventative protection strategy against erosion.
Living plants: Living plants capture the energy the soil microbes need and convert it into an available form.
Pump diversity: Embrace the way nature is designed to work. Daugherty suggests growing diverse cover crop mixes so the soil bacteria have a variety of root exudates to obtain energy from.
Understand tillage and what restores its effects: Tillage is degrading to the way an ecosystem is designed to work, Daugherty says, but integrating livestock can take soil rejuvenation to another level. However, when tillage can be used to help capture energy (establishing a cover crop) where a farmer would have otherwise not been able to, it is better than not doing tillage.
Understanding Carbon
“To me, people that are successful in farming, and especially in cover crop and these regenerative systems, have a good understanding of carbon-to-nitrogen ratios,” Daugherty says. “Not just carbon-to-nitrogen ratios in what's growing above ground, but ratios in the soil and how they're designed and how it's all interconnected.”
Daugherty encourages farmers to rethink carbon, and see it as a vital cycle rather than just something to sequester from the atmosphere. Similarly, Daugherty is not as concerned with an organic matter test result as he is with the process of increasing organic matter percentage in the soil. Building a system in the soil that has a “workforce” of bacteria will help stabilize or increase the organic matter percentage.
“As I build that labor force, this number [organic matter percentage] will increase or stabilize," Daugherty says. “If you're coming from a long-term no-till system and you do a really good job with your covers, it should decrease. You're fixing to bring in more teenagers [hungry bacteria] into the house and you can bring in food to feed them for a little while.”
This understanding, according to Daugherty, determines how a farmer prioritizes and implements cover crops.
“Never plant a straight legume cover crop," Daugherty says. “It's all about balancing. It's where you got to learn carbon-to-nitrogen ratios and energy. When we plant legumes, we bring a lot of nitrogen into the system.”
Energy is needed to synthesize the nitrogen fixed by the legumes, and once the legumes are terminated, the bacteria start to cannibalize the soil aggregates. Daugherty also discourages farmers from planting only brassicas due to their low carbon-to-nitrogen ratio and their tendency to die over the winter. In the spring they aren’t able to capture energy from the sun. The key in cover crop planting is diversity.
“When you have the ability to get some functional groups in there, don't worry about what the name on the bag is,” Daugherty says. “We want some grasses, we want some legumes, we want some broad leaves, we want some brassicas.”
Daugherty encourages farmers to do some research and make their cover crop mix based on their geography and topography. Each field may require a different “recipe.”
Daugherty also warns against discouragement in growing cover crops. A farmer may be frustrated with having to plant them in the fall, discouraged by the stand over the winter and annoyed with planting through them in the spring.
“But then you're going to praise them,” Daugherty says. “That's the way it works.”
“The choice is up to you all,” Daugherty says. “It starts with a commitment to understanding your most valuable resource. It does not matter how degraded it is. Every piece of dirt we have has the potential to be rejuvenated to a more highly functioning ecosystem.”
