Location: Agricultural Systems ResearchTitle: Soil water storage, winter wheat yield, and water-use efficiency with cover crops and nitrogen fertilization
|ZHANG, SHAOHANG - Northwest University|
|WANG, JUN - Northwest University|
|GHIMIRE, RAJAN - New Mexico State University|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2022
Publication Date: 3/17/2022
Citation: Zhang, S., Wang, J., Sainju, U.M., Ghimire, R. 2022. Soil water storage, winter wheat yield, and water-use efficiency with cover crops and nitrogen fertilization. Agronomy Journal. 114(2):1361-1373. https://doi.org/10.1002/agj2.21028.
Interpretive Summary: Winter cover crops extract water from the soil, resulting in less water available to succeeding crops and reducing their yields. The effect of summer cover crops and nitrogen fertilization rates in soil water content and winter wheat yield in dryland farming, however, is not clear. ARS researcher in collaboration with Northwest University, Xian, China, and New Mexico State University reported that summer cover crops reduced soil water and water use of the succeeding winter wheat compared to no cover crop. However, winter wheat yield and water-use efficiency were greater with a mixture of soybean and sudangrass than either soybean or sudangrass alone or the no cover crop treatment, possibly due to increased soil water conservation at winter wheat harvest and N supplied by cover crop residue. Winter wheat yield also increased with increased N fertilization rate. Producers may enhance winter wheat yield and water-use efficiency by using a combination of a mixture of soybean and sudangrass cover crop mixture and a nitrogen fertilization rate 100 lb. nitrogen/acre.
Technical Abstract: Summer cover crops may extract soil water, affecting succeeding winter wheat yield and water-use efficiency (WUE). We examined the effect of summer cover crops and N fertilization rates on precipitation-storage efficiency (PSE), soil water storage during the fallow or cover crop period (SWF), at wheat planting (SWP) and at harvest (SWH), water uptake (SWU), water balance (SWB), winter wheat yield, evapotranspiration (ET), and WUE from 2017-2018 to 2019-2020 at Changwu and Chang’an in the Loess Plateau of China. Cover crops were soybean (SB), sudangrass (SG), soybean and sudangrass mixture (SS), and no cover crop (CK) and N fertilization rates were 0, 60, and 120 kg N ha-1. Soil water to a depth of 2 m was measured by collecting soil samples and aboveground biomass, grain yield, seed weight, harvest index (HI) and WUE recorded. Cover crop biomass was greater with SS than SB at both sites. The PSE, SWP, SWF, SWU, and ET were greater with CK than other cover crops at all N fertilization rates, but SWH, SWB, and HI varied with cover crops, N fertilization rates, years, and sites. Winter wheat aboveground biomass, grain yield, seed weight, and WUE were greater with SS than other cover crops and increased with increased N fertilization rates in all years and sites. Although PSE, SWP, SWF, SWU, and ET were lower, SS and 120 kg N ha-1 produced greater winter wheat yield, heavier seeds, and WUE than other cover crops and N fertilization rates in the Loess Plateau of China.