Recent research has identified how crop rotation in Wisconsin can influence labile pools of C and N. In-short, on Mollisols of southern Wisconsin, big changes in management are required to increase these labile pools. Kalyn Diederich’s (MS Soil Science & Agroecology) poster titled “Increasing labile C and N pools in agricultural soils requires a change in system, rather than practice” was awarded honorable mention in the student poster competition at the Ecology of Soil Health Summit in Fort Collins, CO. This research shows that it is the big shifts – i.e. shifting from grain-based rotations to forage-based rotations to pasture – that cause increases in these biological indicators of soil health, rather than management shifts (e.g. tillage) within a cropping system. A pdf of her poster can be found here.
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).
Interested in hearing more about efficient cropping system management? Then head over to the Wisconsin Dells for the 4th Annual UW Discovery Farms Winter Conference. To register, go to http://www.uwdiscoveryfarms.org/Education/2015WinterConference.aspx.
On January 12 – 14, 2016 the agribusiness industries of Wisconsin will come together at the Alliant Energy Center in Madison for the Wisconsin Crop Management Conference and Agri-Industry Showcase. With over 40 educational sessions, 100,000 square feet of agricultural equipment and services exhibits, and approximately 1200 agricultural industry employees in attendance, the WCMC is the largest agri-industry conference of its kind in the State of Wisconsin.
Craig Culver, co-founder and chairman of the board of Culver’s Restaurants, and Mark Tauscher, former Wisconsin Badger and Green Bay Packer football player, will kick off the event with keynote speeches on day one. According to Shawn Conley, UW soybean extension specialist and WCMC faculty co-director, “We know Mark plans to stick around and sign autographs for a while on Tuesday so bring your footballs.”
Days two and three feature educational sessions on a range of topics including weed, plant disease, nitrogen and nutrients, and soil and water management; seeds and traits, forages and cover crops, manure, and pollinators. Dr. Chad Hart, Iowa State University, will be the final speaker presenting on the Useful to Useable tools (aka U2U). “Make sure to stick around to the end on Thursday,” said Dr. Matt Ruark, UW soils extension specialist and WCMC faculty co-director. “The climate tools that U2U offers have the potential to be quite valuable for farmers and crop consultants.” The U2U program is a USDA National Institute for Food and Agriculture-funded research and extension project designed to improve the resilience and profitability of farms in the Corn Belt amid a variable and changing climate.
Feed, grain, and agribusiness sessions will highlight GMO’s, staff recruiting and retention, and the Food Safety Modernization Act. Also available will be both basic and advanced SnapPlus training sessions. The conference is co-sponsored by the Wisconsin Agri-Business Association, UW College of Agricultural and Life Sciences, and UW Extension. To register, go to http://go.wisc.edu/w51b57.
Interested in what Discovery Farms has been up to this summer? Check out the fact sheet to learn more about how Discovery Farms is communicating science, as well as progress on the Nitrogen Use Efficiency Project and Watersheds. The full document and the September Discovery Farms newsletter can be found at the Discovery Farms website (www.uwdiscoveryfarms.org).
Download the save the date flyer here.
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.
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.
Assessing benefits of radish as a cover crop (Megan Chawner)
Assessing greenhouse gas emissions of dairy manure from tannin in feeding trials (Claire Campbell, poster)
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.
Dr. Sarah Collier, a postdoctoral researcher in the Ruark Lab made the cover of the Wisconsin State Journal, which covered the greenhouse gas tour at the 2014 Agronomy/Soils Field Day at the Arlington Research Station. The complete article can be read here.