Legumes make good forage, N source
Fall-seeded peas or lentils could pan out as a profitable grazing crop as well as an economical nitrogen source for a subsequent wheat crop, say Montana State University (MSU) researchers.
Called ley farming, the above concept was originally developed in Australia as an alternative to the traditional crop-fallow system. It allows for the integration of livestock in a more flexible cropping system in drier climates. While research with ley farming in Montana dates back to the 1970s, the MSU workers have again begun to look at the value of this system for local farmers.
“It appears to be a good fit for farmers who want to be more diversified,” says Chengci Chen, researcher at the university's Central Agricultural Research Center at Moccasin. He says that, according to a 2007 survey of 4,200 Montana farmers and ranchers, over 40% had both crops and livestock in their operations.
“These legumes use less water than a wheat crop and can also provide nitrogen to the soil,” he says. “The crop can be grazed or hayed, and then the stubble can be plowed down as green manure.
“The key with peas and lentils is to terminate the crop at the early bloom stage to prevent the plants from taking too much moisture from the soil.”
He has looked at several other possible rotation crops, including black medic — a traditional Australian legume — and birdsfoot trefoil. But he says the fall-seeded peas and lentils seem to hold the most promise as sources of biomass and nitrogen in central Montana.
“Both peas and lentils grow in the fall, go dormant over the winter and regrow earlier in spring than the other crops,” says Chen.
Several central Montana farmers have tried adding peas or lentils to their crop rotations, he notes. “Some graze the crop in spring, a few have tried to make hay, then they usually plow in the remaining crop for green manure in early to mid-May.” They plant wheat in the fall.
In his research, Chen uses a longvined winter pea variety selected for high forage production. It has outproduced lentils and all the other legumes. On average, the pea crop produced about 2,600 lbs of hay/acre, plus the green manure's nitrogen value is between 30 and 50 lbs/acre.
“So it doesn't eliminate the need for nitrogen, but it greatly reduces it,” he says.
The system offers both economic and agronomic benefits, says MSU economist Dave Buschena. He estimates that there could be, on average, more than a $30/acre net benefit from making hay from the peas, and a $10/acre net return from grazing the forage. Those figures include an estimated 50 lbs of nitrogen added to the soil under grazing and 40 lbs under haying.
But the savings are less about nitrogen and more about eliminating the chemical or tillage costs that are generally used between wheat crops, he says. At current input costs, that's about $25/acre.
With only one season under their belts, the Montana researchers are still somewhat cautious.
“We haven't conducted any grazing studies yet, and we need to determine if peas are winterhardy enough,” says Chen. “But from what we've done so far, and what we hear from farmers who have tried it, peas or lentils could be a good cropping option to add in a crop-livestock system.”