A Good Year for Clover

It's been a good year for clover in most parts of Ontario; lots of moisture and relatively cool temperatures. Now is a good time to take a hard look at your clover growth and assess its value for next year's corn crop.

Traditionally we have given a nitrogen credit of about 45 kg/ha for a clover cover crop. More recently, Greg Stewart of OMAFRA and Ken Janovicek of the University of Guelph have reviewed nitrogen response trials from 1961 to 2004. Their new look at old data confirmed that a good stand of red clover really is worth a lot more nitrogen. The Corn Nitrogen Rate Calculator credits plowed red clover with 82 kg/ha and no-tilled red clover with 67 kg/ha. The difference may be due to the clover top growth being exposed and subject to more nitrogen losses under no-till.

At 82 kg/ha of N , clover is really worth something to the next corn crop. And it is worth managing it better.

Good stands of clover have been hard to get consistently. No-till, high yielding wheat and even earthworms have been blamed for poor clover stands. There are a number of studies underway looking for the cause or causes of poor clover stands and practical ways to establish clover consistently.

The other clover challenge is when to kill it. Clover does a tremendous amount of growth in the fall, both in terms of roots and top growth. To get the most biomass and nitrogen accumulation, let the clover grow until the middle of October or later if time, soil type and weather permit.

Red clover is still the most productive and consistent nitrogen producing cover crop we have available. Its nitrogen release curve is well suited to the corn crop. Manage clover well to get the greatest Nitrogen credit and the most soil benefits from it.