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Improve cover crop catch with proper seeding

Some members of Practical Farmers of Iowa have been experimenting with adding cover crops to their farming systems since the on-farm research program, the Cooperators Program, formally began in 1987.

Several cooperators tested adding winter rye, hairy vetch, oats and other cover crop species to their farming system to reap the benefits that cover crops provide to the system and the surrounding environment through reduced soil erosion, improved nutrient holding and cycling, and pest and weed suppression. Excerpts from two PFI research reports in 1988 and 1989 show the PFI farmers’ curiosity and commitment to solving on-farm challenges.

There can be a problem of reduced crop yields when using cover crops in a dry year. It was a very dry year in 1988, especially on Mark May’s farm at Wilton in southeast Iowa. In fact, 1987 was also a drought year. May was very pleased with equal corn yields following a hairy vetch and oats cover crop.

Allyn Hagensick did not increase or decrease soybean yields with cover crops in north-central Iowa. The negative effect of cover crops robbing moisture from the main crop is very real in dry conditions.

“But we shouldn’t let one negative overshadow the many positive aspects of cover crops: reducing soil erosion, reducing weed pressure, improving soil structure by roots, increasing the population of earthworms, and catching moisture and nitrogen that would otherwise be lost,” the report says.

The report notes: “More trials are in place for next year (1989) to determine just how to minimize the risks in dry years. Two high-boy applicators will be used in the fall of 1988 for seeding the cover crop experiments. The ground applicators give more precise seeding for plots than airplane seeding.”

Interest in cover crops

By 1989, PFI cooperators had built an overseeding rig from a used high-clearance tractor. It allowed them to sow cover crops cheaply in late summer or early fall, before the harvest of cash-crop grain such as corn and soybeans.

“Another important cost-cutting measure is the production of cover crop seed right on the farm,” the report notes. “Using airplanes or ground equipment, you can improve cover crop growth by increasing its planting date.”

In 2011, a new momentum for cover crops is returning to Iowa’s cropland. PFI farmers and staff were invited to speak about using cover crops at events that reached 500 farmers in 2010. In 2011 they are again reaching out to farmers interested in adding cover crops to their farming system.

Also this year, PFI created a Cover Crop Business Directory to help members and others find seed sources, pilots who can overseed cover crops, and cooperatives or other custom applicators that can help manage the cover crop in the spring, while farmers are busy planting corn, soybeans or other cash crops.

Download the latest version of the Cover Crop Business Directory at

Carlson is research and policy director for Practical Farmers of Iowa.

Overseeding planting rate suggestions

Small Grain:
1.5 to 2 bushels per acre

Vetch: 20 to 30 pounds per acre

White clover: 5 to 10 pounds per acre

Red clover: 10 to 15 pounds per acre

Do you want to try it?

Would you like to borrow PFI’s high-boy for on-farm testing?

Contact Sarah Carlson at PFI. If you have modified a high-boy or other overseeding equipment to improve soil-to-seed contact and the ability to seed cover crops seeded earlier, before fall grain harvest, she would like to know about your machine and its results.


Aerial: Picture taken mid-November 2010 of September aerial seeding.


DRILLED: Picture taken mid-November 2010 of October drilled treatment.


BY HAND: Picture taken mid-November 2010 of September hand-planted site.


AERIAL SEEDING: More farmers are experimenting with cover crops. This plane is seeding cover crops into yellowing soybeans on the McGrew Brothers Farm (Bill, David, Robert and Steve) in southwest Iowa.

This article published in the August, 2011 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2011.