How can we get more clover cover crops planted in our fields?

Reprinted from AgWaterExchange (http://agwaterexchange.com/2017/06/12/can-get-clover-cover-crops-planted-fields/)

Legume cover crops, such as red, berseem, and crimson clover, are cover crops that have the clearest short term economic benefit to farmers by supplying nitrogen (N). These plants are rich in N (i.e. have a low C:N ratio) compared to other cover crops like rye or radish. When the clover biomass decomposes, it releases N into the soil, and at the time of peak N uptake of a corn crop. This means that reductions can be made to the amount of in-season N fertilizer application, saving money and reducing the potential for N leaching to tile drains or groundwater resources. No other type of cover crop has shown such a consistent short-term economic benefit.

For farmers with winter wheat in their crop rotation, use of clover species as cover crops provide clear benefits to the corn phase of production in the rotation. Red clover is a popular cover crop that can be “frost seeded” into winter wheat in March or April. This technique involves overseeding red clover at a rate of 12 lb/ac when the soil is dry and has a little bit of cracking. The red clover establishes in the understory of the growing winter wheat crop (Figure 1) and grows quickly following winter wheat harvest. Because of the large amount of biomass that can accumulate, we have been terminating the red clover in the fall. You can let it grow into the spring (it will not winter kill) if you would like to “grow” more N, but timeliness of field operations need to be considered. Research trials have shown that the N credit (or to phrase another way – the fertilizer replacement value) of the red clover can be 45 to 90 lb/ac. It is clear there is an N credit to be taken, but the specific amount appears to be quite variable across growing seasons.

Another option is to plant berseem or crimson clover following winter wheat harvest. In research trials in Sheboygan County, these clovers have been shown to be quite beneficial. Crimson clover has at least a 45 lb/ac N credit, with berseem clover having a lower range (15 to 40 lb-N/ac). Berseem clover, however, has resulted in corn yield gains of 13-15 bu/ac. Demonstrating the dual benefit of the clovers on the subsequent corn crop.

Previous demonstration trials have shown that red clover establishes quite well when interseeded into standing corn (drill seeded at the V4-V5 growth stage) (Figure 2). Current research, funded by the Wisconsin Fertilizer Research Council, is evaluating what the N credit would be for the next year’s corn crop, as well as making sure there are no negative effects on the current corn crop. If successful, this practice could serve to both reduce inorganic fertilizer requirements and improve biological aspects of soil health (which are sometimes lacking in continuous corn systems). The improvement in soil biology could also be beneficial to corn yield.

Overall, it is clear that clovers have tremendous benefit to our corn-based cropping systems. Unfortunately, it requires winter wheat in rotation for it to be easy to get the clover planted in time to get a lot of growth. We have a bit more to learn on the optimum agronomic practices to make sure red clover can grow well when interseeded. As additional on-farm trials are conducted, look for updates at field days and UWEX conferences. In the meantime, I highly recommend playing around with clovers on your fields (staring small to start of course).

Is interseeding of cover crops into corn a viable management practice?

For farmers interested in planting cover crops for erosion, nutrient, and soil health benefits, getting cover crops established in the corn or soybean phases of their crop rotation can be difficult. Drill seeding cover crops when corn is in the mid-vegetive growth stages has been proposed as a management practice. Concerns arise around the competition of water and nutrients – essentially, is the cover crop acting like a weed. Research conducted at the Arlington Agricultural Research Station in 2014 showed that planting cover crops did not reduce corn yield. Full details on the research can be found here. Findings from the 2015 field trial will be presented at the 2015 Soil, Water, and Nutrient Management Meetings.

Interseeding2014

Cover crop and soil quality research presentations

Four research talks and one poster from the 2014 ASA-CSSA-SSSA annual meeting are available for viewing online. The research addresses the effect cover crops, manure application, and crop rotation on carbon, nitrogen, and water cycling and storage.

Building resilience: Effect of long-term crop rotation on soil water characteristics (Sarah Collier)

Long-term tillage, rotation, and perennialization effects on particulate and aggregate organic matter (Anna Cates)

Assessing benefits of radish as a cover crop (Megan Chawner)

Winter rye cover crop and forage comparison following corn silage in south central Wisconsin (Jaimie West)

Assessing greenhouse gas emissions of dairy manure from tannin in feeding trials (Claire Campbell, poster)

Nutrient use and cover crop presentations from Iowa and Minnesota available online

Two of Dr. Ruark’s presentations on nutrient cycling and cover crops are now available online. The first was as part of Minnesota’s Crop Nutrient Management Conference (February 9, 2015 in Mankato, MN). Power points are available on the Minnesota Agricultural Water Resource Center’s website: http://www.mawrc.org/events.html

The second event was the Iowa Cover Crops Conference (February 17-18, 2015 in Des Moines, IA). Power points are available on the Soil and Water Conservation Society’s slideshare site: http://www.slideshare.net/swcsevents. This event also includes presentations from farmers on how they are using cover crops on their farm.

Presentations from Minnesota Cover Crop Symposium available online

Presentations from the Minnesota Cover Crops Symposium, held April 4, 2014 in St. Cloud, MN are available online at http://greenlandsbluewaters.net/resources2/covercrops-symposium.

The symposium covered many cover crop topics including an overview by Rob Myers (USDA-SARE) and presentations from government agencies, seed dealers, agronomists, and farmers, each providing a unique perspective on why and when they would use cover crops and what benefits they are looking for. It also includes my invited presentation on cover crops and nutrient management which includes resent research findings on radish, clover, and rye.

spring barley

Agri-View article highlights research on nitrogen use efficiency

A recent article in Agri-View highlights key research findings on nitrogen crediting from cover crops, use of polymer-coated and nitrification inhibitors, and managing nitrogen on tile drained land. Research was presented at the 2013 Soil, Water, and Nutrient Management Meetings and presentations will be made available shortly.

Full article can be found here.

Nitrogen efficiency: Products, cover crops can improve system

Nitrogen efficiency Products, cover crops can improve system
February 19, 2014 8:30 am  •  Jane Fyksen Crops Editor

Efficient use of nitrogen in corn production makes sense.

That was evident from the big audience UW-Madison soil scientist Matt Ruark had at Corn-Soy Expo in Wisconsin Dells when he addressed the topic, including use of controlled release fertilizers and nitrogen stabilizers and cover crops that supply nitrogen to the next crop.

Noting that nitrogen use efficiency has been on a steady climb upward since the mid-1970s, Ruark still thinks growers should be tracking their nitrogen use efficiency by simply dividing grain produced by nitrogen applied, field-to-field and year-to-year.

The number goes up if yield increases with the same nitrogen rate, yield is maintained with less nitrogen, or best yet, yield goes up with less nitrogen.

Full article can be found here.

Jim Stute wows them at Crop & Pest Management Field Day

Stute 2013

Jim Stute (Department Head & Crop/Soils Educator, Rock County Extension) and Megan Chawner helped out an under-the-weather Matt Ruark at the Diagnostic Training Center’s Crop and Pest Management Field Day. As a team, we gave four hour-long workshop sessions, where we addressed current issues with cover crops and prevented planting and viewed cover crop performance in our demonstration trial. Attendance was about 65 people, which included crop consultants, fertilizer dealers, and government agency employees.

Two handouts were provided: (1) NRCS Technical Note and (2) white paper on evaluating the economic trade-offs between prevent planting payments and harvesting a planned cover crop for forage.

Four big questions asked during this workshop were: 

1) Are there any drawbacks to a rye cover crop in no-till? Preliminary research at the Arlington Agricultural Research Station shows little to no drawback to no-till corn silage yields (data here). However, there is tremendous benefit to soil by having this soil cover after a corn silage harvest. The key to good management in this scenario is to make sure the cover crop is terminated as early as possible to avoid additional competition for nitrogen and water.

2) Will annual ryegrass (aka Italian ryegrass) winterkill in Wisconsin? Annual ryegrass has been known to survive Wisconsin winters and it is important to have a plan for spring termination. Ryegrass has also been known to develop herbicide resistance. However, ryegrass remains a popular cover crop option when flying seed onto standing corn or soybean because of the relatively low seeding rate (22-33 lb/ac of pure live seed) compared to winter rye (60 to 185 lb/ac) or oats (33 to 110 lb/ac).

3) Which legumes are beneficial following winter wheat? Frost seeding red clover (early spring) or berseem/oat mixture post harvest. Crimson clover will also work post harvest, but berseem has been observed to be more consistent in stand establishment.

4) What are the known benefits of radish? Preliminary data can be found here and current research exists in Rock, Sheboygan, and Washington Counties. Preliminary results indicate that radish will increase nitrate concentrations in early season soil nitrate tests, but not enough data has been collected to quantify a nitrogen credit.

Corn University presented by Wisconsin Corn Growers Association

wcga-corn-university-summer-2013_Page_1Joe Lauer, Carrie Laboski, Francisco Arriaga, and I will be presenting at an Extension event on August 5th. This “Corn University” will cover topics of nitrogen, soil, and agronomic management of modern corn production. I will be presenting on nitrogen management of corn (including controlled-release fertilizers and crop rotations) and cover crop management. Click here for more details.

Cover crop considerations for 2012

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With a growing season like we are having in 2012, it is likely that residual nitrate concentrations will be high, especially if corn was harvested early as silage or if yields are well below expected levels. One benefit of planting cover crops after corn silage, small grain, or a processing vegetable crop, or after manure application is that cover crop can take up residual nitrate and reduce the risk of nitrate leaching…(click here to read more)