Thoughts on Cover Crops

The past three years I have tinkered with numerous cover crops here in Lancaster county. Working with colleagues, farmers, and industry seed sellers I’ve established numerous strip plots on farms here in the county. It has been very interesting to see the growth habits of various species and compare this to “book” descriptions.

Thus far all plots have been no-till drilled into corn silage fields. Some of the species which we’ve observed and collected yield and quality data for included the legumes: crimson clover, hairy vetch, and winter peas; the grasses: ryegrass, forage oats, rye, and triticale, and the diakon radish.

We have also evaluated several combinations of species some are calling a “Cover Crop Cocktail.” Space is limited to describe our results and observations but we did learn some important lessons.

Cereal rye is tough to beat

Cost, ease of establishment, late plant-ability, early spring green-up, and absolute yield are all advantages that rye offers. In fact, when planted in two fall manured fields (1st week of Sept.), rye yielded (April 18th harvest) approximately 3 t/a of dry matter and contained just over 200-30-200 lbs/a of N-P2O5-K2O! That’s a lot of recycled nutrients from Fall manure. Many other species yielded about one-half this amount.

In fact, The additional fertility stimulated each species to produce exceptional growth. So much in fact that the hairy vetch, crimson clover and ryegrass all smothered and winterkilled. Growers need to be cautious of this possibility. If we experience a warm fall and you are getting over 6”–8” of growth, consider cutting or grazing as a way to remove some biomass and help prevent winterkill on these three species. Here in the Southeast where we often have an extended growing season, another solution is to delay seeding a week or two for these three species. I feel that we can successfully seed these species into mid to even late September under high fertility conditions.

Keep it Simple

I also planted several combinations of legumes and grasses. In theory, this looked great. The nitrogen and deep tap roots of a legume with the dense fibrous mat of grass should have been an excellent crop to improve the soil and no-till into this spring. What happened? The oats were planted a little thick and out competed the hairy vetch; the ryegrass overtook the crimson clover and even the diakon radish struggled to keep up with the fast growing oats.

Our cost per acre was pretty high and we ended up with a single dominant species or none where we had winterkill. Mixtures can have benefits over and above a single species, but they also add a level of difficulty to our management. Cover crop species selection and use is an exciting area of farmer interest and industry research. Newer and less familiar species do however, come with some hidden risks, as well as benefits.

Let’s not forget the basics and learn the proper planting dates, rates and particulars of each species. What are the primary needs for your farm? Fall or spring forage? Cover for erosion control? A no-till planting seedbed? Legumes for N? Grasses to capture manure N?

Contact Information

Jeffrey S Graybill
  • Extension Educator, Agronomy
Phone: 717-394-6851