Organic Broadcaster

Farmers experiment with cover crop, no-till corn

By Margaret Smith, Iowa State University

Smith and Alert modified a rolling Buffalo stalk chopper to roll down their stand of hairy vetch before planting corn. Photo by Margaret Smith

My husband, Doug Alert, and I have been intrigued with the idea of no-till organic. We see it as a sort of Holy Grail of organic cropping. Wouldn’t it be great to be able to grow crops with no herbicide and no tillage?

We have been following the work of Jeff Moyer and his crew at the Rodale Institute and Steve Groff of Cedar Meadow Farm, both in Pennsylvania. Steve pioneered the use of no-till with rolled cover crops for corn, soybeans, tomatoes and squash. Though not certified organic, he strives to minimize his use of herbicides. The Rodale Institute has taken this work farther and has developed systems for rolling both rye and hairy vetch before no-till planting organic corn and soybeans.

We decided to try the no-till system in 2014. That growing season started with a very wet spring. Though we were able to rotary hoe the corn crop, we were only able to cultivate one fourth of the crop and only once. This has happened to us before, but only with one field in any given year. Last year’s calamity was widespread, and our yield monitor convinced us that we needed alternative strategies for negotiating similar conditions in the future.

Later spring green up of hairy vetch with volunteer rye. Photo by Margaret Smith

In mid-August 2014, we drilled hairy vetch and oats following a rye grain crop in preparation for planting organic corn this spring. Seeding rates were 40 lb/acre for the hairy vetch and about 70 lb/acre for the oats. This was more seed than the generally suggested 25 lb/acre for hairy vetch, but as a first-time look-see, we wanted to make sure to get a stand. Oats were included in the mix on Moyer’s recommendation to help with overwintering of the vetch.

In a nearby field following late corn harvest, we also broadcast 120 lb/acre rye where we had chopped stalks and worked the ground in preparation for planting organic soybeans. Both plantings were five acres for demonstration. There was no replication or randomization of plots that would have allowed statistical analysis.

Both cover crops overwintered. We had a great stand of hairy vetch, but the rye stand was poor. We recognized that if rye is planted late, we will have to drill it to get an adequate stand. In fact, no matter what the cover crop seeding date, to achieve a uniform stand that will suppress weeds, we feel that drilling is required. Broadcasting is generally adequate for farmers who want a general cover crop that will be worked down. Too bad that with our poor stand, we decided to work the rye down and missed the opportunity in 2015 to try rolling it and no-till planting soybeans.

We also had a beautiful red clover stand that had been frost-seeded into the rye grain the previous March. We always get a stand of red clover with this method and it always overwinters, so it’s a tough system to beat!

Recommendations are to let the hairy vetch come to full flower before terminating it by rolling and no-tilling corn into the mat. With a good stand and at full flower, there should be at least 6,000 lbs. of dry matter, which Moyer has observed in their many trials as the minimum necessary to suppress weeds. Our hairy vetch stand was waist- to chest-high, thick and matted—you had to fight your way to walk through the seeding. As this was a first-time demonstration, we did not take samples for dry matter determination, but my guess—and this is only a guess—is that we did have 3 T dry matter/acre.

We found the biggest challenge of this system to be the flower date of hairy vetch. We used VNS (variety not stated), which can be anything! We know that varieties that have thrived in the Upper Midwest and are winter hardy tend to mature later. This may be due to these varieties coming slowly out of dormancy in the spring. Our hairy vetch stand didn’t fully flower until June 6, when we rolled it down with a rolling Buffalo stalk chopper modified to cover the entire width of the unit, rather than the rolling units situated only over crop row areas.

We planted corn on June 8. The comparison corn following rye with red clover underseeding was planted May 22—17 days earlier. During late May, we know that corn yield decreases at least 1 bu/acre/day with delayed planting, and the rate of corn yield drop increases after about June 1.

Doug standing between rolled and unrolled hairy vetch. Photo by Margaret Smith

The second biggest challenge for us was to find an adequate no-till planter able to cut through the mat of still-green hairy vetch stems and leaves, place the seed, and shut the furrow with good seed-to-soil contact. We used a JD Max Emerge 1720 planter with no row cleaners, double disk openers and finger-type row covering wheels. We dropped 33,800 seeds/acre. We did notice some “hairpinning” with cover crop residue pushed down into the seed furrow before seeds were dropped.

On July 1, three weeks post planting, the no-till corn with hairy vetch was in development stage V4, while our earlier planted comparison corn was in stage V8. No-till corn stands averaged 23,333 plants/acre with a range of 14,000 to 32,000. Our comparison corn had a stand of 30,600 plants/acre.

Rolled vetch with volunteer rye. Photo by Margaret Smith

We did achieve 100 percent ground cover with the hairy vetch mat, though some hairy vetch was not completely killed with the single rolling/crimping pass. We have had regular rains, and expect this amount of crop competition will affect yields. After the corn canopied, these partially killed patches did die back. We saw some weeds coming through the residue mat—mostly a few foxtail, but, overall, were happy with weed suppression.

Production costs were within $15 per acre of each other for our two systems (Table 1). Over planting hairy vetch seed brought costs up in the no-till system. In the future, we plan to seed only 25 lb/acre. Profitability then will come down to corn yield and grain moisture levels resulting in different drying costs. It’s clear, just by visual evaluation, that the no-till, later-planted corn will yield less and likely be wetter at harvest. How much so remains to be seen!

The advantage to the system is the major shift in time of labor required compared with our typical organic corn (Table 1). We’re not sure yet if this will prove to be a less risky system for wet springs. We know that corn yields are reduced if we can’t row cultivate. We have many questions about changing weather patterns and the predicted future frequency of wet springs.

What next? We really don’t see this as a viable system in the Upper Midwest unless we can access a hairy vetch variety that flowers sooner. Our search has unearthed two hairy vetch varieties, Purple Bounty and Purple Prosperity, that were developed in the eastern U.S. by the USDA and Rodale Institute specifically for this trait. Purple Bounty is the earlier maturing, reported to flower in the third week of May. The bad news is that the team at Albert Lea Seed in Minnesota has tried to produce this cultivar on farms in southern Minnesota and observed dismal winter survival rates. Purple Bounty is available through La Crosse Seed. We are going to try it this fall and winter to see if our location, 60 miles south of Albert Lea, may make a difference in winter survival.

In addition, we need a different planter or planter configuration to optimize seed survival when no-till planting. Doug thinks that disk row cleaners, regular double disk openers, seed firmers and V closing wheels will do the job planting through the heavy and wet hairy vetch residue mat. We planted 20 acres of Purple Bounty hairy vetch and oats the first week of September to prepare for further experimentation in 2016.
We recommend you use several resources to help you gear up to try this practice. The Rodale Institute’s experiences and Jeff Moyer’s book, Organic No-till Farming: Advancing No-till Agriculture, were invaluable to us. Steve Groff, at Cedar Meadow Farm also has a wealth of experience. Universities in Iowa, Wisconsin and Minnesota are now also researching this practice.

Margaret Smith works in Extension and Outreach at Iowa State University. She and her husband, Doug Alert, have a 950-acre organic grain and livestock farm near Hampton, Iowa.

From the September | October 2015 Issue

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