The Soil Health/Regenerative Agriculture movement is about evaluating the cropping systems we have implemented and determining how they align with Mother Nature’s principles. The prairie soils we are farming now were built to 4 to 7% SOM levels throughout time by the presence of vegetation, with living roots feeding the soil as much of the time as possible throughout the year.
We are trying to emulate the natural system as much as possible and begin to rebuild the soil organic matter to pre-industrial farming times. Soil organic matter is the number one soil health indicator, and it responds quickly to the right combination of regenerative farming practices.
Livestock can play a crucial role in the regeneration of cropland. The herds of bison, elk, and deer that travelled back and forth across the nation’s prairies were kept moving by predators like wolves and grizzly bears following behind them.
Modern day grazers keep their cattle rotating through cool and warm season grass and forage crop paddocks with super portable high tensile wire and post fencing systems, ensuring that the livestock never take more than half the vegetation. The effect of both systems is that the “prairie livestock” never had a chance to overgraze an area, and the manure and urine was spread out across the land.
Over 80% of the nutrients the grazing animals ingested were re-deposited on the land behind them, and the rest of the vegetation was trampled and mixed with the biologically charged soil surface.
Interestingly enough, the microbial systems in a cow’s rumen are 95% like the microbial systems in the soil. After eons of grazing with their mouths clipping grass near the soil surface that should be no surprise. This is why adding grazing provides a turbocharger effect to soil health improvement.
Living roots in the soil support the soil biological systems by leaking the plant sugars produced by photosynthesis. Bacteria, fungi and protozoa living in the rhizosphere support the entire soil food web. Those microbial population levels rise and fall with the existence and number of living roots in the soil.
The challenge we face in a corn soybean rotation is the limited amount of biological time (i.e. warm, sunny days with adequate soil moisture) we have available to grow cover crops after harvest. Currently we have living roots growing from May through September, leaving a minimum of four months, March-April and October-November in a fallow soil state. We can keep the soil biology alive and regenerating by growing cover crops in those windows.
Some farmers are utilizing systems that seed cover crops before the cash crops are harvested to gain valuable time on cover crop establishment.
Airplanes, helicopters, hi-boy seeding units with pneumatic seed delivery and inter-seeding before V4-V6 crop stage are some of the options available. The success of these surface broadcast seedings can depend on receiving timely rainfall in dryland cropping systems.
Other Regenerative Ag farmers are adopting planting corn in wider rows and inner-seeding cover crop mixes shortly afterward containing legumes that provide nitrogen to the corn through the growing season. The regenerative horizon is open wide for some of our most progressive producers.
Another strategy employed is expanding the crop rotation to include cereal grains.
The July harvest time allows for much more biological time to grow up to 20 or more cover crop species mixes that provide a wide range of benefits from nitrogen fixation to cycling phosphorous from deep in the soil. Grazing livestock or renting to grazers cycles the cover crop nutrients in the field and allows for a quicker transition to low input farming.
Benefits of cover crops in Regenerative Agriculture
- A dramatic reduction in soil erosion when combined with continuous no-till systems. You won’t start rebuilding your soil until you stop losing soil! Soil biological systems can only begin to regenerate when soil erosion no longer erodes away the house they live in!
- Sequester excess crop nutrients unused by the cash crop. Cover crop roots can explore the soil to a depth of 4 to 6 feet, returning crop nutrients to the surface in the form of biomass that will cycle and provide the captured nutrients to the next cash crop. This cover crop effect can play a major role in reducing nitrates in groundwater and improving water quality.
- Water use efficiency is improved by cover crops as they improve the infiltration of rainfall into the soil profile. Terminated cover crop residue limits early season evaporation from the soil surface. A 1%t increase in soil organic matter will store .75 of an inch more soil water. Harvest more rainfall, store more rainfall, and use more free water to grow your crops.
- Weed suppression can be realized when the cover crop canopy growth is thick enough. Cereal rye has been shown to suppress germination and delay emergence of marestail, waterhemp and Palmer Amaranth.
- Grazing opportunities are enhanced by the seeding of cover crops. Multi-species cover crops can be planted after small grain harvest, silage harvest, or seed corn production and provide valuable forage while also giving pastures a longer break to obtain adequate regrowth.
- Improved soil health will make herbicides and pesticides less necessary as the soil regenerates. Predator species like lady beetles and spiders thrive in cover crops and their presence in the field before pests arrive gives them an early start to control. Toxic insecticides like neonicotinoids can be left out of the seed treatment packages available. The neonicotinoid family has been shown to have a negative effect on bee and pollinator populations and recent studies are confirming that they don’t pay for themselves in soybean production systems.
Whether you believe in climate change or not, we do know that regenerative farming practices like no-till and cover crops sequester carbon dioxide from the atmosphere as organic matter in the soil. The levels of carbon dioxide in the atmosphere are continually increasing, and the fossil fuels we are burning now, used to be soil organic matter millions of years ago. Farmers can play a big part in changing that trend.
If you are considering getting started with cover crops, stop at your local NRCS or Natural Resources District and check out the attractive cost share programs available. Regenerative farming and improving soil health are good for the farmer, good for the people involved, and good for the environment.