Plan for your cover crops after wheat now!
July can be a hot, dry time to plant cover crops. Here are tips for successfully establishing cover crops this summer.
When nitrogen prices increase, many farmers look to alternatives. Frost seeding red clover into your wheat can reduce your nitrogen bill next summer, 2012. Unfortunately, it is too late to frost seed red clover. Now is the time to start preparing for your cover crop seeding following wheat harvest. Since wheat harvest is often in July, it gives farmers a large window to get their cover crops planted and growing.
The biggest detriment to successful cover crop establishment at this time of year is drought. It is not uncommon to have up to three weeks with no rain, and if moisture is limited, cover crops will not establish very well. Some farmers have overcome dry soils by using irrigation while others have tried slurry seeding cover crops with liquid manure. Both practices have shown positive responses.
Another approach to conserve moisture is to no-till drill a cover crop into wheat stubble. It is recommended that the field be weed-free prior to drilling. Therefore, you will most often need to control weeds with a burndown such as glyphosate prior to drilling.
If you do not use herbicides, a shallow tillage pass will control most weeds and allow the cover crops to outgrow newly germinated weeds. Shallow tillage will also conserve moisture in the soil as compared to deep tillage.
If a wheat herbicide was applied this year, be careful on what cover crops you plant. Very little research data exists on herbicide carryover and its effect on cover crops. The good news is MSU weed scientist Christy Sprague and her team are initiating a study sponsored by Project GREEEN to evaluate cover crop injury from herbicide carryover and should help answer these questions in the future.
In 2003 Kurt Thelen and I wrote a bulletin titled, “No-till drilling cover crops after wheat harvest and their influence on next season’s corn (E-2897).” We compared oilseed radish, hairy vetch, crimson clover and soybeans to a no cover crop control. In this study, anytime a cover crop was used, weeds were dramatically reduced. Two cover crops that provide significant nitrogen are hairy vetch (101 lbs/A) and crimson clover (68 lbs/A), determined by a Pre-sidedress Nitrate Test (PSNT). All cover crops except soybean resulted in higher corn yields as compared to a control. For detailed information you can purchase bulletin E-2897 from the Michigan State University Extension Bookstore.
Planting cover crops after wheat harvest can improve soil, reduce erosion and provide nitrogen for next year’s crop.
If you are looking for nitrogen, you could seed legume cover crops such as crimson clover, hairy vetch (which can become a weed), red clover and Austrian winter pea. Remember to inoculate your legume seed. Grass cover crops such as oats and annual ryegrass scavenge nitrogen in the soil that was not used by the wheat crop. Oilseed radish and the mustards also serve as nitrogen scavengers and have become very popular recently.
If the conditions are not right and your seeding is delayed into September, then winter annual grass species such as cereal rye should be the cover crop of choice.