Bigger Yields with Fewer Inputs

Reprinted from by Drake Larsen

Farm research indicates that adding a third crop is better not only for the environment, but also for   the pocketbook. Bringing a third crop into the standard corn-soybean rotation has shown to increase corn and soybean yields while reducing input costs, since less herbicide and fertilizer are required for the three- year rotation. Longer, diverse rotations reduce weed and disease pressures and, depending on the additional crop, enable farmers to grow their own nitrogen.

Research from USDA, Iowa State University and University of Minnesota, recently published in the journal PLOS One in October, found a three-year rotation of corn-soybean-oats/red clover to be the most profitable. ISU agronomist Matt Liebman and colleagues saw increased soybean yields from 51 bushels per acre in a two-year rotation to nearly 55 bushels per acre where a third crop was added. Similarly, corn yields averaged 11 bushels per acre higher for the longer rotations.

Identical weed control was achieved using six to 10 times fewer chemicals in the longer rotations compared to the corn-soybean rotation. The research demonstrates that longer rotations that can reduce input costs and maintain or increase yields can have an edge in profitability.

Central Iowa farmer Craig Fleishman is conducting on-farm research to study the effect of a third crop on his farm. The prospects for profits and additional long- term benefits that come from improved soil health speak to his bottom line and his passion for soil stewardship. Practical Farmers of Iowa supports the on-farm research through their Cooperator’s  Program.


Finding the balance

Fleishman, of Minburn, is always fine-tuning his soil stewardship practices in what he calls a continuous search to find the “balance between steel and chemicals.” When making management deci- sions, he first considers the motivation for a given practice. He’s found that many practices good for the crops and soil re- quire a bigger time commitment. Driven by childhood memories of dust storms in the neighborhood, he doesn’t mind the time.

Fleishman says he isn’t trying anything new, merely relearning practices his parents and grandparents were doing before. Like many, his family farm shortened its traditionally diverse crop rotation when soybeans were adopted. Soybeans effectively displaced traditional third crops across the Midwest in the 1960s and 1970s. A challenger to small grains in the past, the story of the soybean is an important reminder that it is possible for alternative crops to break onto the scene in a big way. Recognizing that corn and soybeans will still be his dominant crops, Fleishman completed the first year in 2012 of a three- year trial that brings another crop into his farming system. His interest in adding a third crop has grown from his experiences with strip cropping and intercropping.

His experiment consists of four replications of a three-year crop rotation (corn- soybean-oats/red clover) for a total of 12 strips. Strips are 30 feet wide by three- eighths of a mile long. Corn and soybeans were managed with ridge tillage, as on the rest of the farm. Oats and red clover were planted with a Brillion seeder at 2 bushels per acre for oats, plus 14 pounds red clover.

Measure return over time

The idea is to track the results across a full cycle of the three-year rotation. To understand profit over time, economic return is measured  over three  years instead  of one year. Comparing year to year can be misleading, Fleishman points out, and expanding the economic timeline is es- sential to account for benefits gained from reduced weeds and homegrown nitrogen. Fleishman doesn’t claim to have any magic combination. He admits he is just learning,   and   sometimes   the learning curve in agriculture can be steep.

Though the first-year results are not yet tallied, it’s already been a learning experience. Looking back, Fleishman says his third crop seedings should have been planted earlier. The oats were baled as hay because the stand was uneven; a new seeder may be in order. Roundup on corn and soybeans hurt the oats a bit, though this would have less impact in larger blocks. The clover performed well despite the drought, and biological nitrogen fixation continued long after harvest.

Until there are big changes in the available markets, Fleishman doesn’t see a third crop taking over all his acres. There are markets if you seek them out, he says, but at this point it would be saturated fast if third crops catch on. The Fleishman farm doesn’t have livestock; however, having livestock to feed or graze third crops in- creases the potential value to a farmer, es- pecially in times of high feed prices.

Fleishman knows he has fields that are a natural fit for a longer rotation. After perfecting his techniques, he’s thinking about some headlands and highly erodible land that will be next as he scales up. In the search for a balance between steel and chemicals, a third crop seems like a prac- tical piece of the puzzle.

Larsen is a communications and policy associate with Practical Farmers of Iowa.