Field peas may soon allow Iowa grain producers to expand their crop rotation and provide Midwestern pork producers with a new source of home-grown amino acids.

Iowa State University (ISU) Extension Crop Specialist Jim Fawcett and ISU Extension Swine Specialist Tom Miller are currently studying the economic feasibility of growing field peas in southeast Iowa.

“We are trying to double-crop peas after a crop of wheat,” Miller explains. “We harvest the wheat crop around July 1, then come in and plant field peas.”

If all goes as planned, the peas should be done flowering by the end of September and be ripe before a killing frost. Miller believes the growing season is normally long enough, but weather conditions conspired against him in 2004.

“We didn't get them planted until the end of July, and then we were further slowed down by August temperatures that were 6.5 degrees below normal,” Miller adds. “They ended up getting nipped by an early killing frost Oct. 2. We chalked the year up to experience, but feel we could have raised decent peas if we could have gotten them in earlier.”

No New Equipment Needed

Yellow field pea seeds closely resemble soybean seeds when ripe. Peas can be grown using the same drills and harvesting equipment used for soybean production, so no additional equipment is needed.

Field pea acreage is increasing steadily in northern states like North Dakota and Minnesota. They tolerate very cold temperatures when young, but prefer cooler temperatures during flowering. In more southern zones, peas need to be planted either very early or in mid-July so the flowering period misses the heat of summer.

“If soil moisture is a concern with mid-summer plantings, the peas can be seeded up to three inches deep to place the seeds into moisture,” Miller says. “Inoculation of the seed is important for it to provide its own nitrogen.”

Broadening crop rotation has many agronomic benefits, but economic realities have forced farmers to concentrate on crops that offer the most returns, says Miller. He believes double-cropping wheat and peas will be a profitable option.

“Right now, the only crops we have left around here are corn and soybeans,” explains Miller. “That is going to come back and haunt us. Peas won't solve all the problems, but at least they will help. They also are a host to soybean cyst nematodes (SCN), but they won't build up a lot of SCN because they are harvested before SCN gets started.”

Good in Hog Rations

Peas are very good ingredients in hog rations. Phosphorus in field peas is highly digestible, thus reducing phosphorus excretion and the cost of the ration.

A 2003 South Dakota State University swine diet recommendation study by Bob Thaler and Hans Stein suggests that two parts corn and one part soybean meal can be replaced in a ration with three parts field peas. However, protein and energy concentrations vary between field pea varieties. Field peas are currently used as feed extensively throughout Australia, Canada and Europe.

On the Canadian prairies, where large quantities of peas are grown, they have become an important ingredient in hog rations. Big Sky Farms, a 29,000-sow, three-site, SEW (segregated early wean) farm based in Humboldt, Saskatchewan, feeds over 100,000 bu. of peas to hogs every month.

“Big Sky has been including peas in its ration since its inception in 1995,” explains Casey Smit, feed division manager at Big Sky Farms. “Peas are a good source of protein and amino acids such as lysine, and are very palatable in the diet. Most amino acids are supplied synthetically, but when we can supply them naturally through peas, it takes a lot of pressure off.”

Big Sky's ration currently uses feed wheat for its main energy source. Feed wheat is plentiful in Saskatchewan this year, following an early frost in August. The balance of the ration consists of barley, peas, soybean meal, canola meal, calcium, phosphorus, amino acids and canola oil or tallow.

“The Prairie Swine Centre (Saskatoon, Saskatchewan) has done research and found you could increase the level of peas to over 30% on a step-up program,” Smit says. “We currently max out at 25%, due to the availability of peas. The market is quite volatile at times and sometimes they are priced out of the diet. We need to be consistent in our diet, so we limit the amount of peas rather than putting them in and out of the diet.”

Peas vs. Soybeans

Big Sky uses a least-cost diet formulation. Whether peas are economical in this formula depends on their price relative to soybean meal. Since peas have less than half the available protein of soybean meal, they have to keep that spread to remain competitive. Usually, they are cost effective, although poor crops and heavy demand from the human food market has pushed them out of the hog market several times in the past few years.

Field peas are normally assigned a crude protein value of 23.4%. However, protein content can range from 15.5% to 39.7%, depending on the variety. This doesn't cause problems for Big Sky, however, as they purchase peas from a number of different suppliers and store them in one big bin. Nutrient tests are conducted on the entire bin before the peas are added to the ration.

“Peas are very palatable,” Smit says. “Unlike soybeans, they don't need to be processed before we feed them. They must be clean, though; we want 1% or less foreign matter. If you have something like mustard seeds in the feed, pigs will go off feed.”

ISU's Miller believes peas may have a place in Iowa, too. He is particularly excited by the possibility of adding peas to a blend of ethanol byproducts and corn.

“Peas let you pick up a lot of amino acids you were short on,” he theorizes. “It looks like a nice ration on paper, but we haven't done the field studies yet. We have to figure out how to grow these things down here first or we'd have to import them from further north. North Dakota pea producers average 40-50 bu./acre, and some studies in Illinois indicate they could get 40-50-bu. yields after wheat. Whether we can do that here on a yearly basis still remains to be seen.”