ARS | Publication request: Nitrogen fertilization effect on dryland soil water balance and winter wheat yield in the Chinese Loess Plateau

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 3, 2012
Publication Date: December 4, 2012
Citation: Wang, J., Liu, W., Dang, T., Sainju, U.M. 2013. Nitrogen fertilization effect on dryland soil water balance and winter wheat yield in the Chinese Loess Plateau. Agronomy Journal. 105(1):143-149.

Interpretive Summary: In dryland cropping systems, soil available water and N content are some of the major limiting factors for crop production. Precipitation, being the major source of available water for dryland crops, needs to be used efficiently to sustain yields. Crops may not be able to use N efficiently if water is a limiting factor for growth and production. This may result in increased residual N accumulation in the soil after crop harvest, which can degrade environmental quality through increased N leaching in the groundwater and emissions of greenhouse gases, such as N2O. On the other hand, soils enriched with N through manures and fertilizers can increase crop yields in the presence of abundant soil water that may result in increased soil water depletion. Little is known about the effect of N fertilization on soil water balance and winter wheat yield in the Loess Plateau of China. We evaluated the effect of five N fertilization rates (0, 45, 90, 135, and 180 kg N ha-1) on soil water balance, precipitation-storage efficiency (PSE), winter wheat yield, and water-use efficiency (WUE) from 2005 to 2010 in a Heilutu silt loam in an experiment initiated in 1984 in the Loess Plateau of China. Soil water storage at both wheat planting and harvest was lower with N fertilization than without. Nitrogen fertilization increased the summer fallow soil water recharge (SWR) from 19 to 22%, growing season water depletion (SWD) from 21 to 25%, PSE from 19 to 22%, and evapotranspiration (ET) from 7 to 8% compared to no N fertilization. Increased N rate increased soil organic C but had no impact on soil pH in 2005. Wheat yield increased by 244% and WUE by 220% as N rate increased from 0 to 180 kg N ha-1. Although N fertilization reduced soil water storage by depleting more water, it increased winter wheat yield and water-use efficiency by enhancing soil water recharge and precipitation-storage efficiency probably by increasing water holding capacity as a result of increased soil organic matter. Long-term N fertilization can increase winter wheat yield by utilizing soil water more efficiently with minimum impact on soil acidity in the Chinese Loess Plateau.

Technical Abstract: Continuous N fertilization to dryland winter wheat (Triticum aestivum L.) for a long period may have detrimental effect on grain yield due to high water consumption and soil acidity development. We evaluated the effect of five N fertilization rates (0, 45, 90, 135, and 180 kg N ha-1) on soil water balance, precipitation-storage efficiency (PSE), winter wheat yield, and water-use efficiency (WUE) from 2005 to 2010 in a Heilutu silt loam in an experiment initiated in 1984 in the Loess Plateau of China. Soil water storage at both wheat planting and harvest was lower with N fertilization than without. Nitrogen fertilization increased the summer fallow soil water recharge (SWR) from 19 to 22%, growing season water depletion (SWD) from 21 to 25%, PSE from 19 to 22%, and evapotranspiration (ET) from 7 to 8% compared to no N fertilization. Increased N rate increased soil organic C but had no impact on soil pH in 2005. Wheat yield increased by 244% and WUE by 220% as N rate increased from 0 to 180 kg N ha-1. Although N fertilization reduced soil water storage by depleting more water, it increased winter wheat yield and water-use efficiency by enhancing soil water recharge and precipitation-storage efficiency probably by increasing water holding capacity as a result of increased soil organic matter. Long-term N fertilization can increase winter wheat yield by utilizing soil water more efficiently with minimum impact on soil acidity in the Chinese Loess Plateau.