Posted April 3rd, 2014
This information was compiled from the NC Cooperative Extension Cover Crop Workshop on August 2013. These are simple recommendations to make cover crop selection easy. For more information, visit http://growingsmallfarms.ces.ncsu.edu/growingsmallfarms-covcropindex/.
Before you choose a cover crop, you must first decide what you want your cover crop to do and when you are going to plant behind it.
What do you want your cover crop to do?
Produce Nitrogen - Choose a legume like clover, winter peas, or hairy vetch in the fall or cowpeas in the summer.
Provide Organic Matter (Biomass) - Choose a grass like oats, wheat, or rye in the fall or sorghum sudan in the summer.
Break up Soil Compaction – Choose a brassica with deep roots like forage radish or rape in the fall or early spring.
Attract Pollinators – Choose clovers in the fall or buckwheat in the summer.
Mixtures are best for achieving multiple outcomes. A grass/legume mixture will fix nitrogen while providing large amounts of biomass. In fact, the grass will use nitrogen from the soil to grow, causing the legume to fix nitrogen more efficiently.
When will you need to terminate your cover crop?
If you plan to plant a food crop in early spring, try an oats and clover mix. (These will die easier in early spring!) If you’re planting your food crop after mid April, try a hairy vetch/rye mix for optimal nitrogen. (Vetch needs longer to flower!)
For summer cover, try sorghum sudan, pea mix but mow a couple of times so the sudan doesn’t grow out of hand.
If possible, for maximum nitrogen benefit, terminate your cover crop when it flowers but before it starts producing seed. As a general rule, after terminating, wait four weeks before planting to let the cover crop adequately break down in the soil.
Seeding Rates – When planting, use seeding rates recommended on the Forage Planting Guide for North Carolina. For mixtures that get broadcast, still plant each crop at 70%-100% the recommended seeding rate.