By Doug Peterson
As interest in soil health has exploded across the country I have had a lot of questions and calls about planting cover-crop type annuals into perennial pastures and rangeland to "improve soil health."
It goes something like this. "Hey Doug, the row crop farmers are planting cover crops for soil health so we must need to plant cover crops in our grassland to improve soil health. What would be some good species to plant?"
How do you nicely explain that in almost all cases of perennial, introduced pasture or native, rangeland management they don’t need to plant some miracle-cure cover crop to have healthy soil? All they need to do is some basic grassland management.
While no-till, diverse cover crops and livestock can do wonders for improving soil health in degraded cropland, improving soil health in a perennial grassland is usually much easier, faster and in most cases much cheaper than improving a really degraded, annually tilled crop field.
The basic soil health tenants that most soil health proponents teach for both cropland and grasslands are:
- Reduce disturbances to the soil
- Increase plant diversity
- Maintain a living plant root all year long
- Keep the soil covered all year long
- Integrate livestock when possible
So, where do perennial grasslands fit into this soil health picture?
Millions of perennial grassland acres have not ever been tilled or at least have not been disturbed with tillage for many years. When compared with annually tilled cropland, they have pretty good soil structure and soil aggregation. Soil aggregation is a really important factor in the ability of soil to allow water to infiltrate.
Most perennial grassland has at least some plant diversity and may even have as many as 5-10 species in it. While that is not very good compared with native prairie, it is much better than a monoculture of corn or soybeans or wheat. By having a diverse set of plants with different root structures we can maximize the soil depths from which we can pull minerals and water.
Obviously a perennial plant will have a living root in the soil all year long. Annuals, whether they are a cash crop of corn, soybeans, and wheat or a mixture of cover crops will be seasonal and so will only have a living root for a portion of the year. These living roots and their exudates are one of the primary food sources for the soil organisms that are the workhorses of the soil ecosystem.
In grasslands, possibly the hardest of the five soil health tenants to meet is keeping the ground covered all year long. Keeping the soil covered helps reduce moisture evaporation from the soil and prevents the raindrops from impacting the soil and causing erosion. Keeping the soil covered with a thatch of plant material helps provide protection for the organisms in the soil and on the surface.
Integrating livestock back onto land that has been exclusively cropland for many years can be extremely beneficial. The livestock actually add living biology to the soil and their hoof action and animal impact can be used to manipulate plant residues.
But cows are on grasslands all year long, so the soil must be healthy, right?
In most cases grasslands are better than tilled cropland and those cows can be a great asset but they can also be the biggest problem.
The missing link
In most cases most grasslands need more rest/recovery than they are now getting. They need the opportunity for the plants to develop enough leaf and stem material that it can provide a protective covering for the soil. They need the opportunity for the plants to develop a big root system so they can reach down into the soil and pull minerals from deep in the soil profile. To be healthy, plants that are preferred by livestock need to time to regrow after being bitten off to insure plant diversity is maintained.
One of the easiest ways to cheaply improve soil health in your grassland is to close some gates or combine herds, giving those grasslands some much-needed recovery time. There are many names for it: planned grazing, management-intensive grazing, holistic grazing, or rotational grazing. Call it whatever you want, just use it. Providing adequate rest/recovery periods for all the plants in a field, along with grazing periods that are short enough to prevent a second bite on the same plant before it is recovered will do incredible things for your grassland soil health.
The fact is that good pasture/rangeland management has been taught by a lot of folks around the country for a lot of years. The improvements possible from good management really are "settled science," yet there are still millions of acres being overgrazed, millions of acres with most of the water running off, millions of acres with excessive erosion, millions of acres not producing anywhere close to their potential because we are not willing to put a little more thought and effort into our pasture/rangeland management.
Get fired up and get into the soil health game. Your soil and your pocketbook will appreciate it.
A time cover crops might help pasture
With all that said, there are a few times when a planting of annual cover crops can be used to improve soil health in a perennial pasture situation.
In Missouri and other fescue-belt states a diverse cover crop mixture can be used as part of a fescue renovation project or possibly for a similar type brome renovation in the upper Midwest.
A mixture of cover crops, selected specifically to stimulate biologic activity, can be used to improve soil health prior to planting a diverse perennial mixture back into those former monoculture fescue or brome fields.
Peterson is a soil health specialist for NRCS and a Missouri rancher. This article first ran in Beef Producer in June 2015 and has since disappeared from the internet.