This article and information is from Anne Verhallen, Soil Management Specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs.
Early Harvest means cover crop opportunities!
The combines and drills have been doing double time for the last week with the beautiful September weather and early maturing beans. It is great to see the emphasis on getting wheat in this year – we know how important wheat is to a good crop rotation. However, I still see a lot of bare fields. An early harvest like this really offers some opportunities to get a few more cover crops in. Granted at this late date in September we are pretty much looking at the winter cereals like wheat or rye. Their fibrous root systems will establish quickly and help to build better soil aggregates. This is particularly important if you have a lot of soybeans in your rotation.
Let’s face it beans really don’t return much to the soil. They are not in the ground for long and usually the root systems are minimal. Not a lot of opportunity to improve the soil. You have probably heard Dave Hooker at the Ridgetown Campus of the University of Guelph talk about the benefits of wheat in the rotation and Adam Hayes of OMAFRA showing the slaking results of the long term trials. Soybeans especially continuous soys or a soy/corn rotation do not fare well, especially in stress years. It takes getting a grass into the rotation to even things out. So you don’t want to grow wheat? Then consider putting in a wheat or rye cover crop – that will at least get a grass into the rotation for a short period of time and keep your ground protected from erosion over winter.
Now what about all that beautiful clover cover crop out there? One of the big questions in the late summer was does it pay to mow red clover stands? Sure it does if you need to control weeds. Mowing the red clover puts everything in the field back to an even start so the clover has a chance to out compete the weeds. This is especially important to get the most out of the clover in the control of Canada Fleabane. But what about if you don’t have a weedy field – does it pay to mow the clover? Well the research shows that we do get more above ground biomass from the clover if it is mown.
The roots – well that is another story as very few researchers invest the hundreds of hours it takes to measure root growth. However we do know that the plant will behave like plants that have been grazed. Basically the plant will drop some roots after mowing but then as the new growth comes on top this will be matched with expanded root growth – the key here is to give the clover long enough to re grow.
And what about nitrogen from the clover? Is it really going to fix more nitrogen now? Yes. The soil is still quite warm for now. By the end of October though, we will have pretty much maxed out the amount of growth and the amount of nitrogen that that plant is going to fix.
Additional Cover Crop Information:
OMAFRA has a cover crop section as part of their website. It includes discussion on a wide variety of cover crop species and a listing of seed suppliers. There is also a Cover Crop Best Management Practices book in the works.
There is a cover crop decision tool developed through Dr. Laura Van Eerd for cover crop selection in vegetable rotations – http://decision-tool.incovercrops.ca/
The SARE program in the US has a number of cover crop resources. Probably the best cover crop resource is Managing Cover Crops Profitably, 3rd ed, Sustainable Agriculture Network 2007. It is available on line at http://www.sare.org/publications/covercrops/covercrops.pdf
However, keep in mind as you read through it that it is a national US publication and some of the information is not applicable to Ontario conditions.
The Midwest Cover Crop Council hosts a website that has more regional cover crop information
There is a link to a very cool new interactive cover crop decision making tool formost of the states of MCCC. Just as a note the Ontario is based on Ontario historical weather data specific to each county.
Soil Management Specialist (Horticultural Crops)
Ontario Ministry of Agriculture, Food and Rural Affairs
P.O. Box 400, 120 Main Street