Effects of rainfall variability on productivity and profitability in the intensified annual forage–winter wheat cropping systems on the Loess Plateau of China

Intensifying traditional fallow–winter wheat (Triticum aestivum L.) (F–W) system with annual forage can increase productivity and profitability on the Loess Plateau of China. However, the uneven and variability precipitation has led to the productivity is instability. Four-cycles field experiment from 2016 to 2020 to investigate that planting oat (Avena sativa L.), soybean [Glycine max L. (Merr.)], and vetch (Vicia sativa L.) annual forages into summer fallow period on productivity, benefit, and resource use efficiency under R−30% (a 30% decrease in natural rainfall), CK (natural rainfall), and R+30% (a 30% increase in natural rainfall) three rainfall situations. Across four growing seasons with 12 rainfall situations, incorporating annual forages into fallow period significantly increased productivity and resource use efficiency, and the system productivity and net income were influenced by the intra- and interannual variability rainfall. Increasing precipitation significantly enhanced productivity. Compared to CK, the R+30% scenario wheat equivalent yields in F–W, oat–winter wheat (O–W), soybean–winter wheat (S–W), and vetch–winter wheat (V–W) systems were increased by 17.9%, 20.3%, 18.7%, and 25.5%, respectively. In normal years, forage oat, soybean, and vetch yields were 5545, 4339, and 2829 kg ha⁻¹, respectively. The F–W, O–W, S–W, and V–W wheat grain yields were 3785, 3089, 4014, and 3286 kg ha⁻¹, respectively. Compared to F–W, the S–W system net income increased by 30.5%, 33.3%, and 36.3%, respectively, under dry, normal, and wet years. In consideration of yield and profitability, the S–W system is more suitable for local farmers to wheat production under future climate change on the Loess Plateau.