Tailored nitrogen strategies for high productivity in dryland wheat under one-off irrigation

Aims With the advent of the High-Standard Farmland Project in China, one-off irrigation has become feasible for most dryland fields, presenting a novel opportunity to topdressing N for dryland wheat production. However, the effects of split N application under one-off irrigation on wheat production and the underlying mechanisms remains insufficiently understood. This study aimed to determine how split N application affected wheat productivity and soil nitrate-N residue under one-off irrigation. Methods Four N applications (100%, 70%, 50% and 30% N as basal and others as topdressing, namely N100-0, N70-30, N50-50, N30-70, respectively) and zero N (N0) were established in moderate (MF) and poor fertility (PF) fields in a typical drylands in China in 2022–2024. Results Split N application significantly increased wheat grain yield by? and protein content by through increasing pre-anthesis N translocation and post-anthesis N accumulation. Grain protein content was significantly improved by 6.0%, 12.1%, and 15.7% under N70-30, N50-50, and N30-70 in MF, and by 7.7%, 9.1%, and 13.8% in PF, respectively. Both N70-30 and N50-50 increased N uptake efficiency, N agronomy efficiency and partial factor productivity in MF and PF, whereas N30-70 increased N agronomy efficiency in MF but decreased it in PF. Conclusions N50-50 in MF and N70-30 in PF represent the most effective split N strategies for achieving high grain yield, high protein content, and efficient nitrogen use in dryland wheat production system under one-off irrigation, and they provide insights for optimizing N management to enhance both productivity and environmental sustainability under soil fertility variability.