One of the big buzz words in agronomy the last few years is cover crops. While this may seem like a foreign concept to some farmers, others now consider this farming practice simply part of the cropping system. What exactly is a cover crop? There isn’t a simple answer. But rather than debate the correct definition, let’s focus on individual farms. Cover crops can fit pretty much any farm if producers decide to implement them. Do cover crops require management? Yes, but so does any farming practice.
Several benefits of cover crops include:
• improve water quality
• reduce soil erosion
• conserve soil moisture
• reduce nitrogen and phosphorus in water
• use as potential grazing
• possibly reduce weeds
These are only a few of the benefits of planting cover crops. Cover crop goals are specific to each individual farm. It’s important to select the proper cover crop for your operation.
Why do you want to cover up?
The first thing farmers need to ask themselves is, “Can I define my use for cover crops?” Once you do that you can expand your search to include topics like seeding date, type of seed, method of application and location of the cover crop.
We in Extension often get asked about seeding date, as in when is the best time to seed a cover crop? The usual generic answer is, “That depends.” Again, this is where your goals are important.
This fall in Iowa, seeding cover crops was a challenge for producers wanting to drill the cover crop. Aerial seeding was a common method this year due to the late harvest caused by abundant rainfall in most parts of Iowa.
Winter rye was seeded into standing soybeans and corn on Sept. 18. The photo at right shows the soybean field on Nov. 10. Both of these seedings were successful due to the amount of moisture we received in September and early October. The other key factor to the success in establishment was warm temperatures. The photo illustrates the fall growth possible after seven weeks when seeding in mid-September.
Having worked with cover crops for several years in southwest Iowa, I can say seeding date is a moving target for cover crops. Winter rye is one of the most popular fall-seeded cover crops.
I’ve seeded winter rye with a drill on Dec. 2 and had zero growth in fall and winter months. However, by early April, I saw growth of 2 to 4 inches.
My point: You need to understand the species and date you seed a cover crop to have realistic expectations.
One of the most informative cover crop resources a farmer can get is the “Midwest Cover Crops Field Guide.” It’s a handy pocket guide produced by the Midwest Cover Crops Council. In it, you’ll find a calendar showing preferred cover crop seeding periods.
Starting with winter rye
I used winter rye as an example for several reasons. One of the most common reasons for seeding winter rye as a cover crop is because it is the most forgiving in terms of establishment, seeding date, rate and environment. The reasons winter rye is relatively easy to establish is because it will germinate with little moisture and with soil temps as low as 34 degrees F, and emerge in five to eight days. I refer to winter rye as the “beginners’ seed.” It’s an excellent choice for farmers who haven’t tried cover crops or are in their first few years of establishing a cover crop.
In a corn-soybean rotation, we suggest starting with seeding cover crops into corn stubble in the fall, ahead of the next year’s soybean crop. This approach for a beginner is low risk and will jump-start your soil toward higher productivity. Cereal rye is low risk, easy to establish in the fall and easy to kill in the spring.
For farmers with more experience who want to try legumes, brassicas and grasses other than winter rye, look to the "Midwest Cover Crops Field Guide” for more information. Also, visit the Midwest Cover Crop Council website at .
Saeugling is the ISU Extension field agronomist for southwest Iowa. Based at Lewis, you can contact him at firstname.lastname@example.org.
This article published in the December, 2014 edition of WALLACES FARMER.
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