Fall Seeded Legumes Look Good in U.S.

BOZEMAN - Jun 2/08 - PRN -- Projected budgets show a potential for increased profit using fall-seeded peas and lentils for spring grazing and as a nitrogen source for a subsequent wheat crop, say researchers with the Montana Agricultural Experiment Station and Montana State University Extension Service.

Legumes, like peas and lentils, take nitrogen from the air and accumulate it in both the above-ground plant and underground nodules on roots. In the ongoing experiment station study, the legumes also are being used as livestock forage before being plowed into the ground to increase organic matter and nitrogen in the soil.

Dave Buschena, an MSU economist working on the project, said that he used estimates of low and high forage yields, the nitrogen benefit to the following spring wheat crop and the hay benefit of the pea crop. Using 2008 costs, Buschena estimated that there would be on average more than $30 in net per acre benefits from haying for forage and about a $10 per acre net benefit return from grazing. The large returns from haying reflect the strong market for hay, he said.

"The estimates of nitrogen and haying or grazing benefits of the pea crop appear to offset the seed and machinery operating costs for peas," he said. These returns should be compared to the cost of chemical or tillage fallow, currently estimated to be almost $25 per acre, instead of the pea crop.

Buschena said the budgets used were for the pea crop to add 50 pounds of nitrogen to the soil under grazing and 40 pounds under haying. These levels are estimates based on previous work. Actual nitrogen benefits will be less in drier zones and drier years, and greater in wetter conditions.

This nitrogen benefit from peas reduced, but did not completely eliminate, the amount of urea that needed to be applied for a subsequent wheat crop, he added.

However, the projected benefits need to be verified in practice, so, Chengci Chen, a researcher at the Central Agricultural Research Center at Moccasin, began such a study with last fall's seeding. Chen said the work builds on work done in the 1970s by MSU agronomist Jim Sims, who studied black medic and other legume crops in crop rotations that are traditionally called "ley farming" in Australia.

In a normal year, shallow soil profiles such as those in central Montana are refilled over the winter. Even with that, however, soil moisture usually is the most limited resource in dryland cropping, so an important requirement for this system to work is that the peas be terminated early to avoid soil moisture loss, said Chen. That can be done by grazing and terminating the peas at the early bloom stage in the spring.

Chen has black medic, a traditional nitrogen source in Australian ley farming, in the research, as well as birdsfoot trefoil, a perennial forage legume. However, fall-seeded peas and lentils now look like the most promising nitrogen and biomass sources, since the medic has a fairly low biomass in Montana and relatively late spring emergence.

"The advantage of winter pea and lentil is that they grow in the fall, turn dormant over winter, and re-grow earlier in the spring than black medic. They also produce more biomass," Chen said. "The idea is to use a legume to fix nitrogen and add to soil with nitrogen and organic matter. Both benefit the subsequent cereal crop."

Clain Jones, MSU Extension soil fertility specialist in the Department of Land Resources and Environmental Sciences, said with high nitrogen prices, having either an intercrop or a rotation with legumes could give an economic benefit to both conventional and organic farmers, even though the actual benefits still need to be determined. Additional research will be conducted under this project to more fully understand the nitrogen benefits.

Under a Western Sustainable Agriculture Research and Education or "SARE" grant, the research team led by Chen began the study with a survey of Montana farmers in 2007 to find whether any were using ley-farming systems.

The survey indicated that about 43% of Montana farmers and ranchers have both livestock and crops on their farms/ranches. Three farmers, Theo Wright of Lewistown, Jon Kvaalen of Lambert and Jess Alger of the Stanford area, responded that they were using peas, lentils and/or black medic in integrated crop-livestock systems.