Can winter field peas, planted in September and harvested the middle of the following summer (like winter wheat), work as part of the dryland cropping rotations in the Nebraska Panhandle? The question is being studied by the alternative crops breeding program at the University of Nebraska-Lincoln Panhandle Research and Extension Center at Scottsbluff.

Incorporating winter pea into a wheat-based dryland crop production system in the Panhandle has the potential to increase the crop production sustainability and economic viability of dryland farming in the Nebraska Panhandle and High Plains in general.

Field pea is a broadleaf legume that is low-water-use and can fix biological nitrogen. For the first time, winter field pea varieties are being tested in Nebraska as a winter crop. Spring-planted peas have been produced commercially in Nebraska since around 2011. Nebraska pea acreage has grown from around 20,000 acres to 50,000 acres.

One year of variety trials under irrigation has been completed at Scottsbluff and similar trials will be expanded in 2021-22 under dryland (no-irrigation) production environments. The trials have been planted in Cheyenne County (Sidney) and Perkins County (Grant) for harvest next summer.

Winter field pea is grown in the Pacific Northwest for food-grade grain. Neighboring states such South Dakota and western Kansas have been testing winter pea production. 

Dryland crop acreage in the Panhandle is dominated by winter wheat, a fall-planted, grass-type annual crop. Currently, there is no fall-planted broadleaf crop grown in rotation with winter wheat. Winter pea is planted around the same time as wheat.

Wheat growers here have few economically viable alternative crops to use in rotation with winter wheat. Scarcity of water has led to widespread reliance on monocultures of winter wheat-summer fallow to conserve soil moisture. 

Presently, none of the economically viable alternative crops are fall-sown annual broadleaf crops. Current rotation choices in addition to wheat include spring or summer-sown pea and proso millet/sunflower/corn. 

Winter pea is attractive for its potential to diversity and intensify wheat-based cropping systems in the semi-arid High Plains. The potential benefits and advantages are numerous:

Winter pea typically out-yields spring-planted pea by 20 to 30 bushels per acre. The crop can be planted more reliably at the optimal planting time than spring pea, due to late snows. Winter pea is less susceptible to heat and drought conditions during flowering time, which frequently limit yield in spring-planted pea.

Planting a crop in the fall provides vegetative cover until the following spring, reducing wind erosion of soil. Pea has the potential to increase the environmental resiliency of a farm by scavenging nitrogen from the soil, thus preventing groundwater contamination and limiting production of the greenhouse gas nitrous oxide.

Winter pea also has the potential to improve weed management, increase water-use efficiency of the system, and help manage wheat stem sawfly by breaking the pest cycle.

The goal of the 2020-21 variety trials at Scottsbluff was to identify suitable food-grade winter pea varieties for the Panhandle — to see if commercially available varieties would survive Nebraska winter and compare yields. Since this was the first year, the testing was conducted under irrigation to reduce the uncertainty; however, actual production of winter pea is under dryland, which is being tested in 2021-22.

In the first year of trials, 14 winter-pea varieties were planted in mid-September 2020. The varieties were from commercial seed companies (ProGene Plant Research, Pulse USA and Seed Ranch Co.,) and public breeding programs (U.S. Department of Agriculture Agricultural Research Service, Pullman, Wash.). 

The trial plots were irrigated to ensure good emergence and stand before the plants entered dormancy over the winter. All 14 varieties had excellent winter survival, with no winter kill. Irrigation was continued in the spring as needed. The total amount of irrigation water applied was 6.5 inches, in addition to five inches of total precipitation from planting to harvest. All varieties flowered between the end of May and the first week of June. The trial was harvested in July. 

Average grain yield was 51 bushels per acre, ranging from 24 bushels per acre (Austrian Winter Pea, a forage variety sold by Seed Ranch that is commonly harvested in May for hay) to 71 pounds per acre (Pro 164-7117 from ProGene Plant Research). Test weights ranged from 53 pounds per bushel (Austrian Winter Pea) to 62 pounds per bushel (Vail from ProGene). 

The next year of trials were planted in September, with data expected in the summer of 2022. If the dryland trial is as successful as the 2020-21 trial, winter pea could be a game-changer for dryland (rain-fed) wheat production systems. One important question to be answered is the optimal window for planting.

Potential longer-term benefits of adding winter pea to a dryland crop rotation include income stability and improved risk management. The USDA Risk Management Agency insurance program is favorable to manage farm-level risks associated with winter pea production. This could enable producers to spread risk among multiple commodity crops, particularly where there is only currently cereal production.

Food-quality winter pea is also a highly nutritious source of plant-based protein and other nutrients such as micronutrients, vitamins, dietary fiber, resistant starch, and antioxidants, as well as in supplying high-protein feed for local livestock industry.