Jeff Burbrink

By JEFF BURBRINK
Extension Educator, Purdue Extension Elkhart County

GOSHEN — Our Elkhart County SWCD held an interesting meeting this week.  Cameron Mills, a farmer from Cass County, was one of the speakers. Mills has being using cover crops on his farm for a number of years now and he shared some interesting ideas and experiences with the group.

The motivation to use cover crops comes from his desire to improve the soil. By doing so, he believes he will improve profitability also. I believe he’s on to something.

Cover crops secure nutrients from washing or blowing away and they encourage earthworms and other soil organisms to break down the plant material in the soil. This, in turn, increases soil organic matter, which helps improve drainage and tilth of the soil.

When it comes to timing of the seeding of the cover crops, Mills has found that he prefers seeding in August, while the crop is still standing and soils are warmer, as compared to seeding after the crop is removed and the soils are cooling. He has had better fortunes with aerial seeding than with ground based seeding systems. The preferred seedling mix has been annual ryegrass with some rapeseed and crown vetch thrown in.

As is typical with cover crops, the cover crop is killed in the spring, a few days before seeding the corn or soybeans. Mills has learned that patience is important when deciding when to kill the cover crop. Many people try to kill the cover crop as soon as the annual ryegrass greens up. However, for the herbicide to work most effectively, the plant needs to be actively growing. Typically, that has been 3 to 4 inches in height.

Mills also stressed the importance of herbicide selection on the corn and bean crop. From some personal observations and experience, he has learned to select products with little or no residual carryover that would affect the cover crop. This is not always easy to find on a pesticide label, but is extremely important to reduce the stress on the newly seeded cover crops in August. He cited some work by Penn State’s Bill Curran and Dwight Lingenfelter here for more information.

I was struck by one on-farm experiment Mills tried to measure the effect of cover crops. You’ll recall that in 2012, much of northern Indiana was affected by drought and, as a result, it was suspected that much of the nitrogen applied was not used by the corn crop. In December, Mills measured nitrogen in areas without a cover crop to the 24 inch depth.

He found, on average, there were about 110 pounds of nitrogen per acre in the soil. Areas under the cover crop, however, had only 10 pounds of nitrogen available per acre. His conclusion is the cover crop has locked down that nitrogen and captured it for next season’s crop.

As a follow-up to that same experiment, he tested the soil once again in April.  The area without the cover crop came back with only 30 pounds of nitrogen per acre, while the area under the cover crop remained about 10 pounds of nitrogen per acre. That 80-pound difference of nitrogen from December to April is nitrogen that will need to be applied and paid for, again, during the next growing season.

I am encouraged to see more interest in cover crops, no-till and conservation practices such as filter strips and nutrient based manure applications. With margins being tight on our grain crops right now, it is a good time to look at alternative options that can help improve the bottom line in the long run. If you are not sure where to start, stop by your county’s Soil and Water Conservation Office. There are some incentives available for a limited time for people who are interested.