Winter wheat response to winter pea cover crop under dryland cropping

Authors: Gollany, Hero

Submitted to: Crops and Soils
Publication Type: Popular Publication
Publication Acceptance Date: 1/3/2024
Publication Date: 1/15/2024
Citation: Gollany, H.T. 2024. Winter wheat response to winter pea cover crop under dryland cropping. Crops and Soils. 57(1):50-53. https://doi.org/10.1002/crso.20334.
DOI: https://doi.org/10.1002/crso.20334

Interpretive Summary: Cover cropping has been used in farming for centuries before the development of synthetic fertilizers. A long-term no-till experiment (NTA) winter wheat-fallow rotation was established in 1982. The experiment was a randomized complete-block design with four replications of five N rates. A second set of four replications winter wheat-fallow rotation was established 30 feet north of NTA in 1997 as winter wheat-fallow under no-till (NTB) before being converted in fall 2010 to a winter wheat-winter pea (W-P) cover crop. Both phases of the rotation were present every year. Each experiment had four replications of five nitrogen fertilizer rates (0, 40, 80, 120, and 160 lb. N/acre/year) as subplots. Between 2012 - 2021, average wheat grain yields in the winter wheat-winter pea cover crop increased by 6, 17, and 10 bushels/acre compared to the winter wheat-fallow in the 0, 40, and 80 lb N/acre fertilizer rates, respectively. The winter wheat yield increases in the winter wheat-winter pea cover crop plots occurred despite 8 of 10 experimental years receiving below-average precipitation. Wheat yields in cover crop plots equaled or exceeded those in the wheat-fallow across all N rates, indicating that water use by the winter pea cover crop does not significantly impact wheat yields the following year. Cover cropping with legumes such as winter peas under dryland winter wheat production systems has several benefits that could improve the resiliency of production systems in the intermediate (12- 16 inch) rainfall zone under a Mediterranean climate.

Technical Abstract: Cover cropping has been used in farming for centuries before the development of synthetic fertilizers. A long-term no-till experiment (NTA) winter wheat–fallow (W-F) rotation was established in 1982. The experiment was a randomized complete-block design with four replications of five N rates. A second set of four replications, previously under conventional moldboard plow tillage winter wheat–fallow rotation was established 30 feet north of NTA in 1997 as winter wheat–fallow under no-till (NTB) before being converted in fall 2010 to a winter wheat–winter pea (W-P) cover crop. Both phases of the rotation were present every year. Each experiment had four replications of five nitrogen fertilizer rates (0, 40, 80, 120, and 160 lb. N/acre/year) as subplots. Winter pea cover crops were terminated after flowering and before winter pea pod formation. Between 2012 - 2021, average wheat grain yields in the winter wheat–winter pea cover crop (NTB) increased considerably by 6, 17, and 10 bushels/acre compared to the winter wheat-fallow (NTA) in the 0, 40, and 80 lb N/acre fertilizer rates, respectively. During the past 5 years, further increases in wheat yields in the 40 and 80-lb. N/acre fertilizer rates were observed with winter wheat–winter pea cover crop exceeding winter wheat–fallow by 26 and 19 bushels/acre, respectively. The winter wheat yield increases in the NTB plots occurred despite 8 of 10 experimental years receiving below-average precipitation. Wheat yields in NTB cover crop plots equaled or exceeded those in the NTA plots in wheat–fallow across all N rates, indicating that water use by the winter pea cover crop does not significantly impact wheat yields the following year. Cover cropping with legumes such as winter peas under dryland winter wheat production systems has several benefits that could improve the resiliency of production systems in the intermediate (12 – 16 inch) rainfall zone under a Mediterranean climate.