Cattle graze cover crops in a field.
The last several years have seen a surge of interest in using cover crops in cropping rotations. Much of the promotion of cover cropping benefits has come from farmers who have developed successful cover crop systems and have documented improvements in soil health parameters.
Some of the cover crop gurus see 'getting livestock back on the land' (ie, grazing) as the final step in making a cover crop program reach its full potential. Cover crop promoters who are also in the beef cattle business and graze cover crops have documented soil health improvements and at the same time realized significant savings in feeding costs.
The question gets to be 'what should I do'? The answer is not the same for every operation. There are a lot of questions to be answered before you can decide what to do.
Are you already in the cropping business? I've never been a promoter of using only annual crops for beef cow grazing. Research by Comerford et al. at Penn State (2005) clearly showed that a system of annuals (sudangrass, rape, small grains, corn stalks) was not cost effective for grazing beef cows compared to systems of perennial grasses and legumes. However, there are windows where annuals may fit. Renovation is one window. Another window is where the annual is being used as a cover crop in the context of a larger program. The cover crop is planted for many purposes, one of which is grazing livestock. In this situation the beef cattle owner is also in the cash crop business or contracts with a cash crop farmer to allow grazing of cover crops. In this scenario the lengthening of the grazing season can save enough on hay costs that it could pay. And, if you are already in the cropping business, you likely own the equipment necessary to plant a cover crop.
What class of cattle do you have? Nutritional requirements vary from class to class. Properly timed plantings of annuals can make a great system to put weight on growing cattle. In 2005 I had the opportunity to spend a week in the Pampas region of Argentina to learn more about forage finishing systems for beef cattle. One of the aspects of this that I found very impressive was how much cheap weight gain was being put on growing beef cattle by grazing cover crops after cash crops. I refer to this as double-cropping the land with cattle. No mechanical harvest or storage systems needed. Interestingly, the primary cover crop being grazed was oats.
What are your soil types and associated drainage capabilities? Even if you don't know the actual names of your soil types, you probably have a good feel for the productive capability and the drainage characteristics of the soils on your farm. Extremely heavy, wet soils could be a problem for grazing cover crops, since much of the time-frame for grazing cover crops might be late in the season or perhaps early the following season.
What is the fencing situation? Most land being cropped is not fenced. Then the question gets to be 'what amount of fence am I comfortable with'? There are many temporary fence options that could be employed, but they are not physical barriers. In some areas, with low population and low levels of traffic, a cattle owner with brood cows might be comfortable with a minimal amount of fence. In other areas of the state, where there are more people, a cattle owner would be taking a significant risk by using a temporary arrangement for fence to graze a cover crop. The decision also may differ if the cattle are young stock.
The crop species we can use for cover crops and grazing is extensive. Common choices for covers include cereal grains, oats, annual ryegrass, peas, vetch, sudangrass, brassicas, and clovers. Selection will depend on what time of the season we can plant (summer, late summer, early fall, late fall), do we want a cover that winter kills or not, seed costs, grass versus legume, etc. Many of the aforementioned cover crop gurus who also graze cattle indicate that they have been most successful with diverse mixtures of cover crop species. Diverse mixes can serve the purpose of improving soil health, holding soil, and providing cheap forage.
Recent field trials conducted with annual ryegrass varieties at Penn State have shown impressive yields of forage. Fields were planted after corn silage harvest, around the third week of September, and harvested three times during May and June. The top several varieties yielded over 6 tons of dry matter. I relate this to show what one species of cover crop can do in terms of providing forage, whether it be grazed or mechanically harvested.
The decision to use cover crops as part of a grazing strategy will differ from farm to farm. Each person needs to decide this based on their own resources and goals. And, as they say, if two farms are doing exactly the same thing, then probably one of them is wrong.