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The Risks and Benefits of Grazing Cover Crops

June 17, 2024 - Paul Anderson, AFM

The benefits of cover crops have long been celebrated in the agriculture community. Hailed as unsung heroes, they are known to prevent erosion, improve soil structure, and suppress weeds. Grazing cover crops is simply the next logical chapter in the regenerative saga. Soil enthusiasts champion this natural method of maintaining soil fertility, likening it to nature's own recycling program. As attractive as the concept is, many farmers are hesitant to put it into practice. Their primary concern is that introducing cattle to tillable ground, especially during seasons prone to more moisture, will lead to soil compaction. While there is some validity to that concern, there are effective strategies to mitigate these risks and enhance the overall benefits to soil health.

Grazing cover crops is a win-win scenario that bridges the gap between livestock and grain production. For the livestock producer, it offers a cost-effective feed source while saving the labor required to harvest feed and haul manure. For the grain producer, the benefits are numerous. A study conducted by Grass Fed Insights, LLC showed that 1 animal unit (a 1,000 lb. animal) grazing cover crops can produce 0.25 lbs. of Nitrogen (N), 0.15 lbs. of Phosphorus (P), and 0.52 lbs. of Potassium (K) per day. Assuming a stocking rate of 0.75 animal units per acre and a 60-day grazing period, a total of 11.3 lbs. of Nitrogen, 6.8 lbs. of Phosphorus, and 23.4 lbs. of Potassium. If the following cash crop is corn with the expectation of a 200 bu./ac yield, the manure will offset an estimated 5% of the N requirements, 11% of the P requirements, and nearly 53% of the K requirements for that crop. Additional benefits include increased organic matter, which improves the soil’s water-holding capacity. Microbial activity is enhanced, making soil nutrients more available to plants, and the trampled crop residue provides a barrier to prevent erosion and inhibit weed growth. While the benefits of grazing cover crops are significant, it’s important to consider the potential for soil compaction and the issues that can arise from it.

Soil compaction reduces the pore spaces within the soil, hindering water and air infiltration and restricting root growth. Studies by Iowa State University found that soil compaction can reduce yield by as much as 10 to 20 percent, depending on multiple factors. Besides impeding the cash crop, compacted soils are more susceptible to runoff and erosion. The perception has always been that as cattle graze, their weight and movement will cause compaction, especially under wet soil conditions. Newer research shows that with proper management, soil compaction is less severe than widely believed and may even be negligible. A study by the USDA showed that soil bulk densities were only slightly higher after six years of grazing cover crops while a study by the University of Nebraska Lincoln showed no change in penetration resistance or bulk density after one year. A Practical Farms of Iowa study found that only the top four inches of soil showed minor signs of soil compaction while depths beyond that showed no indication of compaction at all. These studies share a common theme: they all incorporated a series of best practices in their grazing plans. Which, in turn, raises the question: What are the best practices?

Avoiding soil compaction is achievable if some basic principles are applied:

• First, and most importantly, avoid grazing during wet and muddy conditions. If cattle can be removed from the cover crops, that would be optimal. If the cattle cannot be removed, confine them to the fastest-draining areas or areas with the most mature vegetation.

• Secondly, avoid concentrated traffic. Provide mobile water tanks and supplemental feed sites that can be regularly moved around the field. Limit access to creeks, ponds, and other areas where cattle tend to congregate, such as shady spots and natural windbreaks. If certain areas are known to be vulnerable, it may be best to exclude those areas from grazing completely.

• Lastly, establish a plan to rotationally graze the cattle around the field. The plan should include the dates and under what conditions the cattle will be moved. Limiting the amount of time cattle are allowed to graze in an area will limit compaction and optimize forage use.

Grazing cover crops is a tale of balance. The benefits of enhanced nutrient cycling and organic matter must be weighed against the risk of soil compaction. With careful management and strategic planning, the relationship between cattle and crops can foster soil health rather than hinder it. If you are interested in more information or would like to connect with a Peoples Company Land Manager, please visit PeoplesCompany.com or email LandManagement@PeoplesCompany.com.

Published in: Land Management