Taking the kura (clover) cure
It seems odd to say that after 10 years, they are still at the early stages of research into kura clover. Used as a perennial cover crop, it offers a promising addition to corn and soybean production systems, but there are still a lot of questions to ask.
Here at the largest of the University of Minnesota Extension Service Outreach and Research Center (4,000 acres-plus), UMore Park in Rosemount, Professor John Baker began looking at kura clover in 2006. His work has been funded in part by Minnesota Corn Research & Promotion Council, which has placed a priority on solutions to enhance water quality.
The first decade of work with kura promises solutions to sediment and nutrient loss problems that occur in particularly sensitive areas of the farming landscape — steep slopes and the margins of waterways.
Kura creates water infiltration rates 8-10 times higher than in conventional corn and soybean systems. A tour of the Rosemount kura plots took place the night after a half-inch rain. Not only could they drive heavy equipment on the field, but they demonstrated a rotary zone tillage machine, used to create a rows for corn right through the sea of clover.
The infiltration rate is the key, according to Baker, for phenomenal reductions of hillside erosion. In a special plot on a nine-degree slope, they measured erosion side by side from conventional corn, and corn with kura between the rows. In 2015, 10 major storms carried eight tons of soil down the slope in the conventional system. Where the kura was in place, the loss was only a half-ton.
Unlike alfalfa and other clovers, a kura stand does not need to be taken out every 5-7 years. It forms a dense, green mat that survives perennially with minimal attention, and without the periodic soil disturbance needed to grow those other legumes. This would have a ‘set-it-and-forget-it’ appeal for farmers who already have a lot on their plate (and after the initial cost, kura would not be an annual expense like annual cover crop seed).
Because of its ability to scavenge any leftover nitrogen, kura would make an excellent planting for vegetative waterways down hillsides, and for vegetative buffers.
“I’m not saying farmers should farm all the way up to the stream bank, but you could put in a fifty foot buffer of kura, and still farm thirty feet of that ground, so you don’t lose so much production,” Baker suggested.
Graduate student Michelle Dobbratz has set up an experiment to find the most effective tillage system for working in kura. Band killing with herbicide was the original approach pioneered by Wisconsin researchers, but continual use of glyphosate worked a little too well, and after a while, the kura needed a rest year —not very effective for an agricultural field where a farmer, naturally, wants to produce a crop every year.
A custom built rotary till machine is showing promising results for being able to plant every year into the kura cover, with a corn-bean or even corn-corn-bean rotation.
Baker calls the use of kura underneath and around corn and soybean rows ‘living mulch.’ In order for the kura to survive, all the corn stover has to be removed at harvest. If it were left to lay on top of the clover, it would kill it. But, Baker points out, the kura itself provides plenty of biomass that returns nutrients and organic matter to the soil. And farmers can then market their stover as animal bedding, feed, or as feedstock for advanced biofuels.
Just like every good farming system, in a kura system, nothing is wasted.