Diversification and intensification of irrigated maize‐based cropping systems under Mediterranean conditions

Abstract Under Mediterranean irrigated conditions cover cropping (CC) and double cropping (DC) are diversification/intensification strategies that can increase grain yield and resource use efficiency of the traditional winter fallow‐maize ( Zea mays L.) system. Four cropping systems were evaluated in terms of productivity, water and nitrogen use efficiency (WUE and NUE) under sprinkler‐irrigated conditions during three growing seasons in the Ebro Valley, Spain: (1) long‐season maize with winter fallow (F‐LSM), (2) long‐season maize after a leguminous cover crop (common vetch, Vicia sativa L.) (CC‐LSM), (3) short‐season maize after a cereal crop (barley, Hordeum vulgare L.) (B‐SSM), (4) short‐season maize after a leguminous crop (winter peas, Pisum sativum L.) (P‐SSM). The introduction of the vetch winter cover crop required an additional 5% irrigation water but allowed to reduce the nitrogen fertilizer applied by 20%, increasing the system grain yield synthetic nitrogen use efficiency (NUEsynt‐g) by 27% without affecting the cropping system grain yield and WUE. DC systems required 12% more irrigation water than the traditional F‐LSM but produced more grain. The B‐SSM was the most productive system (21.9 Mg grain ha −1 ) and increased the WUE by 32% compared to the F‐LSM system, but required a 39% more nitrogen fertilizer. Compared to the traditional F‐LSM system, the P‐SSM cropping system increased the grain yield (+16%), protein yield (+66%), NUEsynt‐g (+20%), and the WUE (+10%). The diversification and intensification of the traditional F‐LSM system increased yield (with the DC systems) and resource use efficiency (WUE with the DC systems; NUE with CC‐LSM and P‐SSM cropping systems).