Double Cropping Field Peas Offer Economic Sustainability for Midwest Swine Producers

2008 Annual Report for LNC05-257

Project Type: Research and Education
Funds awarded in 2005: $109,651.00
Projected End Date: 12/31/2009
Region: North Central
State: Iowa
Project Coordinator:
Dr. Jim Fawcett
Iowa State University

Double Cropping Field Peas Offer Economic Sustainability for Midwest Swine Producers


Background: The typical Iowa swine farmer raises about 5000 head of hogs as well as corn and soybeans. In order to use soybeans as a protein source for the swine it is necessary to process the soybeans. Field peas have been grown successfully by farmers in other states and countries and used as a substitute for soybean meal. Inputs which require no processing, grown and used on the farm have generally improved farm profits.

Project Outcomes: The feasibility of growing field peas in Southeast Iowa will be completed. Double cropped field peas will be evaluated for disease, insect susceptibility, yield and nutrition attributes and the economics compared to the standard corn-soybean rotation. Swine producers who grow and use field peas as a source of protein and energy in swine diets could potentially increase profits by more than $35,000.

Objectives/Performance Targets

Small scale Iowa State University replicated research plots as well as field scale cooperator plots will be set up to evaluate variety selection, time of planting, harvesting techniques, and pest management of field peas. Feeding trials will evaluate the economical inclusion rates of field peas into swine rations.


Economic evaluation based on net return per acre, comparing field peas in a double-crop production system compared to the control which for this study is the current corn/soybean rotation with the purchase of soybean meal from off farm commercial sources.

The second part of the evaluation will be the economic return to the producer feeding field peas compared to the control. Evaluation will be based on performance of the swine comparing health, cost/lb of gain, average daily gain, and feed efficiency.


A double cropping system utilizing spring planted field peas followed by soybeans was successful in 2005, with pea yields of 40-50 bu/A and double cropped soybean yields of greater than 20 bu/A in both field scale trials and small plot research.

Yields of both crops were less in 2006, probably partly due to later planting dates in 2006 and to unusually warm weather in late May when the peas were flowering and setting pods. Yields were better in 2007 and 2008, but not as high as ’05 yields, perhaps partly due to excess spring rainfall. A winter pea variety planted in the fall of 2005 at the SE Iowa Research & Demonstration Farm yielded slightly better than the spring pea varieties, but did not mature any sooner. A different winter pea variety planted on two planting dates in the fall of 2006 suffered severe winterkill and was not harvested.

One cooperator experimented with double-cropped milo after spring planted peas in 2006 and achieved milo yields of greater than 60 bu/A, even with a July 10 milo planting date. Based on this success and the low yields of double cropped soybeans, the double cropped soybeans were replaced with double cropped milo in 2007. Yields of double cropped milo planted on July 3 were about 90 bu/A at the research farm in 2007. Milo yields were about half of this in 2008, probably due to the later planting date of July 15 due to the wet spring. The double cropped milo was not planted until August 1 in the large field near Amana in 2007, so little grain was harvested, but the forage was utilized for cattle feed.

The double cropping system of winter wheat followed by summer planted peas has not been successful in any year. Although winter wheat yields were good in all years, the best field pea yield achieved was 19 bu/A with a late July planting date of the variety “Admiral” in small plots in 2005. Pea yields in field scale plots have generally been less than 10 bu/A. Summer planted peas were not worth harvesting on the research farm in 2007 or 2008 and no large fields were planted in 2007 or 2008.

In 2007 and 2008, organic farmers investigated whether peas could be used as a nurse crop for establishing alfalfa and red clover. In 2007, a late freeze resulted in close to 100% kill of the red clover seeded with peas. Pea yields were fairly poor (18 bu/A) partly due to poor plant stands and lack of weed control. In 2008, the very wet spring resulted in the seedings being delayed until mid-April, which resulted in poor pea yields (17 bu/A), although alfalfa and red clover stands were acceptable.

Fairly extensive testing of field peas was done to give a basic understanding of nutritional levels. The Iowa peas were about 86% dry matter (14% moisture), which is a level that will store well. Crude fat averaged about 2%, although the 2005 spring varieties were less than 1%. Crude fiber was 5 to 6%. Ash was about 3% and crude protein averaged 20%.

Field peas are a good source of lysine (about 1.54%), which is commonly the first limiting amino acid in pig diets. Unfortunately, peas are low in methionine and tryptophan (0.20%,). Digestibility of these amino acids is lower in peas than in soybean meal. It may be advisable to add synthetic methionine and tryptophan to swine diets containing high levels of peas. Threonine average 0.74% in the winter, summer, and spring peas averaged about 0.74%. The amino acid levels in the Iowa-grown peas were similar to NRC table values. Field peas are low in fat compared with corn and contain twice as much fiber as corn. Therefore, peas are lower in energy than corn.

The first feeding trial was conducted the fall/winter of 2005-06 involving a 1200 head finishing site with two replications of each treatment – 1) corn-soy, 2) Eclipse (variety) 300 lbs/ton field pea inclusion, and 3) WFP 0097(variety) 300 lb/ton field pea inclusion. Due to an outbreak of Circovirus within the site only one replication of each treatment was used in the final analysis. Performance of pigs on all diets was affected by disease outbreak but field pea and corn-soy diets showed no difference in average daily gain (ADG), which averaged 2 lbs/day. Rations were balanced for caloric intake. Excellent results were obtained from feeding field peas. The feed efficiency of the WFP 0097 variety of field peas (2.26) showed a statistical improvement over the other two diets.

A feeding trial using market barrows comparing diets containing spring planted peas, summer planted peas, and winter peas with a standard corn/soy based diet was conducted at the ISU Swine Nutrition Research Farm, Ames, IA during the fall of 2006. All pigs were in good health during the experiment period. Initial body weights did not differ between dietary treatments, as part of the experimental design. There was no difference in final weight for pigs in the four treatment groups and no treatment effects on ADG across dietary treatments. The Adjusted Daily Feed Intake was influenced by dietary treatments. Pigs tended to consume less corn-soybean meal and spring pea diets than the winter and summer pea diets.

In this study, the results showed no decrease in performance of finishing pigs at the inclusion rate of 30% field peas in a corn-based diet. There was no adverse effect on growth rate or feed conversion among the treatment groups. The 30% field pea inclusion rate was enough to replace all the soybean meal and reduce the corn. In the diets containing peas, synthetic lysine, tryptophan and threonine were added to the pea diets to avoid deficiencies.

The feeding trials indicate that swine producers can increase their profits by utilizing field peas in the ration, especially with today’s very high corn and soybean meal prices. However, a profitable cropping system utilizing field peas in Iowa is yet to be found. An economic analysis of the cropping systems investigated on the SE Iowa Research & Demonstration Farm indicated that none of the rotations including field peas could compete with the corn-soybean rotation with the crop yields obtained in the trials. Intercropping systems, such as using peas as a nurse crop for establishing a legume or seeding peas with a small grain for a feed crop, may be the best utilization for field peas in Iowa.

Impacts and Contributions/Outcomes

Midwest crop and swine producers are learning about the possibility of increasing their economic sustainability by utilizing double-cropped field peas in swine rations by seeing the many articles that have appeared in the press about the project.

Area producers learned about double cropped field peas at a field day held at the SE Iowa Research Farm near Crawfordsville in 2005 at on Amana Farms in the spring of 2006.

Presentations on the project results were presented at the Agronomy Society Association conference in Indianapolis and at the Integrated Crop Management Conference in Ames, IA in November of 2006.

A poster summarizing the results was presented at the Agronomy Society Association conference in New Orleans in 2007. Several copies of the poster are being produced to be displayed at field days and other events.


Shaun Greiner
Swine Producer
2453 Kiwi Ave
Washington, IA 52353
Terry Erb
3265 320th St
Wellman, IA 52356
Office Phone: 3196462855
Tom Bonnichsen

Crop Producer
15771 Hwy 92
Letts, IA 52754
Steve Fouch
Organic Farmer
92nd Ave
Pleasantville, IA
Office Phone: 6418427167
John Stanton
1404 County Road D61
Bernard, IA 52032
Office Phone: 5638527206
Tom Miller
Project Planning Specialist (Agriculture)
Iowa State University Extension
209 South Marion Ave.
Washington, IA 52353
Office Phone: 3196534811
Rich Gassman
Crop Manager
Amana Farms
P.O. Box 189
Amana, IA 52203
Office Phone: 3196223791
Brad Dvorsky
Crop Producer
2038 Jordan Creek Rd NE
Solon, IA 52333
Office Phone: 3196243062
James Petersen
Organic Farmer
Quebec St
Knoxville, IA
Office Phone: 6418287490