Black-Eyed Pea in the High Plains

Old Crop, New Lens

When studying the regions of origin for black-eyed pea production in Africa and the region of production in the U.S. in the early 20th century, environmental similarities were identified when comparing the High Plains to these historical production regions. This analysis led to the supposition that black-eyed pea was a viable candidate to meet the demands of High Plains agriculture as a dryland or limited-irrigation crop.

Black-eyed pea is an annual legume with an inherent adaptation to heat and drought. It is more drought resistant than many spring-planted crops grown in the semi-arid High Plains such as corn, grain sorghum, and soybean (Hall, 2012). Black-eyed pea is well-suited for growth under dryland and limited-irrigation conditions in the High Plains. This is because precipitation is limited but still sufficient for its production, and the Ogallala Aquifer that many irrigated farmers rely on for water is rapidly depleting, creating a need for the production of crops with lower water use requirements (Scanlon, 2012).

Why Now? Mainstream Fit as an Alternative Crop

Dry edible beans (especially pintos) have historically been the primary grain legume grown in Colorado, but acreage has declined by 90% in the past 30 years. In eastern Colorado, the cropping systems primarily consist of grass species, such as winter wheat, corn, grain sorghum, and proso millet. Currently, there is limited production of broadleaf crops such as sunflower (primarily dryland) and sugarbeet and dry bean (irrigated) due to production challenges and markets. There is fast-growing interest in black-eyed pea due to its potential to diversify crop rotations, break weed cycles, reduce water use, improve human and ecological health, reduce fertilizer inputs, and improve economic outcomes for farmers. It can be grown on dryland and irrigated acres, which is unique compared with other legume crops traditionally grown in the region.

The market for black-eyed pea has grown steadily over the past nine years in eastern Colorado. The number of dry bean processors who contract black-eyed pea production has grown from one to three, and processors exist in western Kansas and the Nebraska panhandle. Farmers are interested because black-eye pea is generally more valuable on a per-pound basis than other dry bean classes due to top-end yield limitations under irrigated production. Processors are also contracting production on dryland acres, making it a high-value dryland crop for producers. There is a need for U.S.-based production to reduce the black-eyed pea imported from South America. The national production average was 1583 lb/ac in 2023 (USDA-NASS, 2024). Based on our experience with growers in northeast Colorado and western Nebraska, dryland yield typically ranges from 300 to 1200 lb/acre while irrigated yield has ranged from 1000 to 2400 lb/acre.

As acreage increases, questions about the best ways to grow and manage black-eyed pea in our region to optimize crop rotation benefits and profitability are surfacing. To achieve their potential in Colorado, we realized that we needed targeted, practical research to answer producer questions.

Past Research Overview

Research on black-eyed pea began at Colorado State University in 2019 when Dr. María Muñoz-Amatriaín planted a subset of 368 cultivated cowpea accessions from the University of California–Riverside (UCR) Minicore collection. She tested the lines for adaptation to dryland and limited-irrigation conditions under field conditions in Colorado. She made crosses of black-eyed pea lines with desirable traits such as early flowering, maturity, and drought tolerance. Early-generation breeding populations were generated from those crosses before she left Colorado State University (CSU) in 2022.

aYields corrected to 14% moisture.

Dr. Muñoz-Amatriaín was instrumental in garnering researcher collaboration and industry support in Colorado for black-eyed pea breeding and agronomic research. Beginning in 2020, the CSU Crops Testing Program collaborated with Dr. Muñoz-Amatriaín and planted the 19 most adapted cowpea and black-eyed pea accessions from the collection in a dryland field variety performance trial at Akron, CO. That year Akron had a severe wind and hailstorm in June that damaged seedlings. Akron received 2.9 inches of rainfall in May, which provided good moisture at planting. Only 2.8 inches of rainfall was recorded from June through August, making it one of the driest summers on record. Even with these extreme environmental conditions, the black-eyed pea average yield was 728 lb/ac with a low of 240 lb/ac up to a high of 1188 lb/ac (Table 1). This yield level demonstrates that even in the harshest conditions where other crops failed, certain accessions of cowpeas were hardly affected. Pinto beans were also planted in the trial to allow for a direct comparison, and they produced no measurable yield (Figure 3). In 2023, we started testing lines under limited irrigation conditions in addition to dryland.

In 2021 and 2022, Joel Schneekloth, a Regional Water Resources Specialist at CSU, led a study in northeastern Colorado that had four irrigation treatments: rainfed, 4 inches applied irrigation, 8 inches applied irrigation, and full irrigation. He maintained the historical average rainfall across all treatments to learn the water use requirements for optimum black-eyed pea yield. Irrigating beyond 8 inches of applied water did not increase yield. The evapotranspiration at this irrigation amount was 15 inches, lower than the requirement for pinto beans, which is 19.5 inches. The two-year yield averages were 1185 lb/ac for dryland and 2469 lb/acre for irrigated. Black-eyed pea was also shown to extract less water from the soil compared with proso millet (Schneekloth et al., 2023).

Current Research Overview

Agronomic

After observing how well the crop performed under drought conditions, we expanded our research efforts to define best management practices for Colorado production. We continue to do variety performance trials at Akron, CO. We are also collaborating closely with other CSU researchers to conduct agronomic studies comparing the effects of row spacing, planting populations, inoculation, and N and P fertilization. Although production guidelines exist for other regions of the U.S., none exist for our area of the High Plains yet. In light of that, we have developed a factsheet through CSU Extension, Black-Eyed Pea Production for Eastern Colorado, that has completed peer review and will be published by the end of 2024. The factsheet outlines potential benefits and drawbacks to production along with guidelines for growing the crop in our area. We are also working to secure funding with other CSU and USDA-ARS collaborators to do in-depth agronomic research over three years to create a more extensive and complete black-eyed pea production guide for the region.

Breeding Efforts

The two commercial varieties grown in Colorado are CB5 and CB46, developed by the UCR in the 1940s and 1980s, respectively. Both fit into irrigated and dryland production settings, but in our multi-year performance trials, other accessions have shown more favorable yield and desirable agronomic characteristics over the commercial lines (Tables 1 and 2). Accessions that have done well in Colorado have also been shared with researchers in other High Plains states (Kansas and South Dakota) to test broad adaptation to our region. In the fall of 2024, our program restarted black-eyed pea breeding efforts that had been on pause since the departure of Dr. Muñoz-Amatriaín. We have planted the F2 breeding populations in the greenhouse and are making new crosses based on accession yield performance and earliness, plant uprightness, seed size, and other desirable traits. We think it is advantageous to continue exploring new crosses, particularly to find varieties better suited for the High Plains. We have decided to focus our long-term research efforts more heavily on black-eyed pea due to our belief that it has a permanent fit in eastern Colorado.

aYield corrected to 14% moisture.

bAn LSD (alpha 0.05) has been used to minimize the risk of false positive results, or concluding there is a difference when one doesn't exist. Varieties in the top yield group are in bold.

Acknowledgments

The black-eyed pea research performed by the Crops Testing Program was partly funded by the Colorado Department of Agriculture and the CSU College of Agriculture Sciences. The authors acknowledge and appreciate the collaboration and efforts of María Muñoz-Amatriaín, Joel Schneekloth, Judy Harrington, and student interns London Breese and Ayden Marler.

References

FAOSTAT. (2024). Food and Agriculture Organization of the United Nations. https://www.fao.org/faostat/en/#home

Hall, A. E. (2012). Phenotyping cowpeas for adaptation to drought. Frontiers in Physiology, 3, 155. https://doi.org/10.3389/fphys.2012.00155

Johnson, J., Jones-Diamond, S., Asfeld, E., Kluth, D., & Muñoz-Amatriain, M. (2020). 2020 Colorado dry bean variety performance trials (Technical Report). Colorado State University College of Agricultural Sciences, Department of Soil & Crop Sciences, and Extension.

Jones-Diamond, S., Asfeld, E., Muñoz-Amatriain, M., Roberts, R., Schneekloth, J., Davis, J. G., Barrett, E., Witkze, D., & Harrington, J. (2022). 2022 Colorado dry bean and cowpea variety performance trials (Technical Report). Colorado State University College of Agricultural Sciences, Department of Soil & Crop Sciences, and Extension.

Osipitan, O. A., Fields, J. S., Lo, S., & Cuvaca, I. (2021). Production systems and prospects of cowpea (Vigna unguiculata (L.) Walp.) in the United States. Agronomy, 11(11), 2312. https://doi.org/10.3390/agronomy11112312

Scanlon, B. R., Faunt, C. C., Longuevergne, L., & McMahon, P. B. (2012). Groundwater depletion and sustainability of irrigation in the U.S. High Plains and Central Valley. Proceedings of the National Academy of Sciences, 109(24), 9320–9325. https://doi.org/10.1073/pnas.1200311109

Schneekloth, J., Jones-Diamond, S., Muñoz-Amatriaín, M., & Witzke, D. (2023). Black-eyed peas as an alternative crop for irrigated and dryland cropping systems in the High Plains. Abstracts of the 2023 ASA, CSSA, and SSSA International Annual Meeting, St. Louis, MO. https://scisoc.confex.com/scisoc/2023am/meetingapp.cgi/Paper/152697

USDA-NASS. (2024). U.S. Department of Agriculture, National Agricultural Statistics Service. https://www.nass.usda.gov