Prior to the beginning of the SARE project, a diverse multi-species winter-killed cover crop mix (Forage Max) was obtained from Prairie Creek Seed (http://www.prairiecreekseed.com/) and no-till drilled into one acre of soybean stubble on September 17, 2018 using a John Deere 750 15-foot no-till drill owned by neighbor Knude Ullerup of Altona, Illinois. Due to the late planting the cover crop did not reach optimum growth and maximum cover. Resulting residue cover in the spring of 2019 was estimated at 10-20 percent at time of kura clover planting.
Kura clover living legume mulch systems have been shown to be an ecologically sound, effective weed suppression method in soybeans (Iowa State University, 2007; https://crops.extension.iastate.edu/soybean/production_kuraclover.html) and corn (Ken Albrecht, University of Wisconsin-Madison, 2007; https://crops.extension.iastate.edu/files/article/Experienceswithkuracloverlivingmulchcroppingsystems.pdf) under research conditions. However, kura clover as a living mulch is slow to establish (“sleep stage”), presenting first-year weed control problems. After establishment, for organic farmers wanting to use living legume mulches, there are practical technical problems related to kura clover suppression/control within the cash crop row without the use of conventional herbicides, as well as practical management of the kura clover competition and height between the rows. This project proposes: 1) to establish kura clover into one acre of a winter-killed cover crop/soybean stubble mix using a no-till drill to minimize first-year weed growth until the kura clover fills in; then 2) use a tractor-mounted strip tillage tool (Orthman 1tRIPr strip tiller or comparable equipment; http://www.orthman.com/our-products.aspx?itemid=2048&pagetitle=1tRIPr) after establishment (“creep stage”) to prepare a clean, clover-free uniform seedbed for sweet corn planting. Once the kura clover is fully established (“leap stage”), 3) mechanical control of inter-row kura clover growth will be attempted using an inter-row crimper/roller tool from Walnut Creek Seeds, LLC (https://www.walnutcreekseeds.com/Dawn-Biologic.html) or comparable equipment.
Twenty pounds of kura clover seed along with species-specific inoculum was ordered through Prairie Creek Seed, Cascade, Iowa in early spring of 2019 (http://www.prairiecreekseed.com/). Prior to planting, the seed was also inoculated with a four-species blend of mycorrhizae obtained from Sustainable Ag Technologies (https://composttea.com/), adhered to the seed with water, organic molasses, and a dilute compost tea extracted from fresh bacterial/fungal compost of a Johnson-Su bioreactor (https://regenerationinternational.org/bioreactor/).
The recommended planting date in this area for kura clover is the first week in May. Despite a cold wet spring that delayed most field operations, a warm dry spell during the first week of May permitted drying of the soil enough to allow no-till drilling of the inoculated kura clover seed on May 16, 2019 @ 20 lbs/A seeding rate, along with a forage oats nurse crop using a Vermeer 15-foot 4-hopper no-till drill owned by neighbor Brad Williams of Victoria, Illinois and pulled by my tractor, a 1974 AC 180, 55 hp. The oat nurse crop was seeded at 50 lbs/A. The soil temperature ranged between 54 and 59 degrees, depending on the time of day. Because of the small seed size and low amount of seed compared to the hopper size, actual kura seed dispersal was uneven. Manual brushing of the seed into the cups was necessary, and resulted in some cups running out before others. Nevertheless, the above-normal seeding rate (double the recommended 10 lb./A) gave a satisfactory emergence after six days. The overall result was an uneven stand throughout the plot. Seedling emergence was noted on May 24, 2019. Heavy rains resumed about this time and continued through the rest of the month.
Record rainfall during the month of May, 2019 drowned out most of the kura stand, resulting in sparse and sporadic survival. Clover does not like wet soils, and this is true for kura clover as well. The oats cover helped wick out soil moisture but also shaded the kura clover, which further delayed growth and development.
The rains did not stop in this area until the first week in June, 2019, and the ground was so soggy as to prevent any entry to the field without rutting or damaging the stand. Standing water remained in the kura clover well into the first week of June. Consequently, no sweet corn was planted in the growing season of 2019 for this project. Other growers experienced the same problem, sweet corn was in short supply the entire summer, and many farmers were unable to plant field corn or soybeans at all and had to resort to planting summer cover crops through the USDA Prevented Plant program. The growing season of 2019 became a period of observation and learning.
The plot was periodically rotary mowed during the summer by neighbor Alan Haynes of Altona, Illinois using a John Deere 3-point hitch rear rotary mower mounted to a John Deere 4000 tractor. The mowing gave satisfactory weed and oats control but left residue bunched in areas, smothering some of the kura stand. Flail mowing is recommended but a flail mower was unavailable except to purchase locally. A flail mower was not requested in the SARE budget.
Written notes and photographs were taken throughout the season. Some reddening and yellowing of the young Kura leaves was observed, plant tissue samples were taken and analyzed by TPS Agricultural Consulting and Laboratory out of Edinburg, Texas (https://www.tpslab.com/). Results came back deficient in potassium and nitrogen. Potassium sulfate was recommended as a foliar spray but I do not have a sprayer. The nitrogen deficiency was likely due to poor nodulation. Kura requires a species-specific Rhizobium inoculum that was likely old. More attention will be given to proper inoculation in the future. The plants outgrew the K-deficiency symptoms, so no potassium was applied. At the end of the season, 3 tons/A lime was applied by a commercial applicator to correct soil pH of 5.3.
emerged kura and oat seedlings
emerged kura and oats
My project objectives:
1) To successfully establish a dense stand of kura clover as a living mulch;
2) To apply an innovative mechanical strip tillage method for seedbed preparation to interseed sweet corn into the established kura clover;
3) To test out an inter-row crimper/roller to control any aggressiveness in the growth or spread of the kura clover;
4) The proposed demonstration site is adjacent to a state highway, so I will promote the project by posting signs for passersby;
5) To document the project through photographs/video, take growth and yield measurements, and issue a press release to the media.
Addendum — February 15, 2020
Having learned from NRCS soil conservation principles (https://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/nd/soils/health/?cid=nrcseprd1300631) and innovative regenerative practices of the importance of multi-species diversity in cropping systems, especially cover crops, and the value of inter-species interactions above and below ground, I have modified the first objective to include other perennial low-growing species, notably bluegrass, dwarf white clover, dandelion, chickweed, plaintain, balansa clover, among other, to be planted along with the kura clover in additional plots while keeping the existing kura clover stand. Since the original budget did not call for the additional species, I will pay for the seed out of pocket.
Recent research from the University Minnesota also shows strip tilling may not leave a wide enough strip to prevent competition between the kura clover and sweet corn. Instead, their findings indicated rotary tillage was more effective at creating a more suitable seed bed to optimize corn emergence while minimizing competition from the kura clover (https://www.mda.state.mn.us/optimizing-establishment-corn-cover-crops-and-living-mulches-maintain-yield-while-reducing-nitrate)
Therefore, the first two objectives are modified to:
- To successfully establish a dense stand of low-growing perennial mixed plant species featuring primarily Kura clover as a living mulch;
- To apply available equipment options (strip-tillers, rotary tillers, rotary strip tillers), with modifications as needed, to optimize sweet corn establishment while maintaining the kura clover stand.
Initial steps to carry out this project are to identify possible sources of organic seed, both kura clover and sweet corn, and to review strip-tiller and inter-row crimper/roller options. The field has already been prepared with a winter-killed cover crop/bean stubble mix suitable for no-till planting of Kura clover in the spring of 2019. No-till planting into a mulch is essential for organic weed control because Kura clover is slow to establish the first year. After reviewing strip-till equipment options, a decision will be made and the equipment acquired in time for pre-plant strip tilling. Strip tilling and planting together in one operation is not an option because of the cost of tiller/planter combination equipment. First-year sweet corn planting will be delayed to accommodate other field work and planting, and to enable time to mount and adjust the strip tiller gangs. Hand weeding the corn stand will be required at least for the first year due to the slow emergence, growth and establishment of the Kura clover. The inter-row crimper roller will be acquired in the second year after the Kura clover is established. For educational purposes signs will be placed at the farm borders with information about the project; equipment will be available at the farm for interested farmers to view and assess. Participating farmer will be available to answer questions and show equipment to farmers stopping by. On-going documentation using photographs and videos all three growing seasons (2019-2021) will be made and press releases sent out at the end of each summer with yields and technical results included. As previously mentioned, A Field Day will be held in the summer of the final year of the project (2021).
A photo of a readily available strip-till implement is provided.