Soil mineral nitrogen and winter wheat nitrogen productivity influenced by summer cover crop and nitrogen fertilization

Abstract

Cover crops and nitrogen (N) fertilization may affect soil mineral N, N uptake, and N productivity (grain yield per unit plant available N) in wheat (Triticum aestivum L.). We evaluated the effect of summer cover crops and N fertilization rates on soil mineral N and winter wheat grain yield, N uptake, and N productivity in the Loess Plateau of China. We measured cover crop aboveground biomass N, soil mineral N (0-20 cm), and winter wheat yield, N uptake, and N productivity for four seasons from 2017-2018 to 2020-2021. Cover crops were soybean (Glycine max L., SB), sudangrass (Sorghum sudanense [Piper] Stapf, SG], soybean and sudangrass mixture (SS), and no cover crop (CK) and N fertilization rates were 0, 60, and 120 kg N ha⁻¹ applied to wheat. The SB increased cover crop biomass N and soil mineral N by 15 to 65%, but SS increased winter wheat yield, protein concentration, and N uptake by 25 to 55% compared to SG and CK at most N fertilization rates and years. Nitrogen fertilization rate had a variable effect on cover crop and wheat parameters. Wheat N productivity was 55 to 85% greater with CK than cover crops, but decreased with increased N fertilization rates. The N fertilizer equivalence of cover crops for wheat yield and N uptake ranged from 31 kg N ha⁻¹ for SG to 150 kg N ha⁻¹ for SS. Overall, SS with 60 kg N ha⁻¹ can sustain winter wheat N uptake and N productivity compared to SG or CK with or without N fertilization.

Keywords:

• Cover cropping
• crop quality
• crop yield
• nitrogen application
• nitrogen fertilizer equivalence
• nitrogen productivity

Disclosure statement

The authors declare that there are no conflict of interest.

Additional information

Funding

This study was supported by the Chinese Academy of Sciences ‘Light of West China’ Program for Introduced Talent in the West, the National Natural Science Foundation of China (Grant No. 31570440), the Key International Scientific and Technological Cooperation and Exchange Project of Shaanxi Province, China (Grant No. 2020KWZ-010), the Shaanxi Agricultural Science & Technology Innovation-Driven Project (NYKJ-2021-XA-005), National Key Research and Development Program of China (2023YFE0122900), the National Natural Science Foundation of China (Grant No. 42277322), and Shaanxi Agri-cultural Science & Technology Innovation-Driven Project (NYKJ-2021-XA-005, NYKJ-2022-XA-004).