LAUSR

Abstract Manure has been used as a source of nutrients in grain crop production for millennia worldwide. However, whether and how manure applications benefit water use efficiency (WUE) still remains incomplete, especially in the North China Plain under water deficient conditions. A three-year split-plot field experiment was established with (W1) and without (W0) irrigation at the wheat jointing stage as main plots. Fertilization treatments were included as sub-plots with no fertilizer (F0), 100 % chemical fertilizer N (Fc), 100 % manure N (Fm), and 50 % chemical fertilizer N + 50 % manure N (Fc + m). W1 rarely affected WUE of winter wheat in the normal season, but increased that by 67 % in the dry season, compared to W0. W1 had a rare effect on evapotranspiration (ET) and WUE of summer maize. Overall, W1 decreased annual WUE of wheat-maize system by 9% in the normal years, while it increased that by 8% in the dry years. Manure application (Fm and Fc + m) increased WUE of winter wheat by 5–9 % compared to chemical fertilization (Fc), due to the lower ET after anthesis. However, manure application decreased WUE of summer maize by 6–10 % than chemical fertilization, which caused by the higher ET before anthesis. Therefore, fertilization strategies had a minor effect on annual WUE of wheat-maize system. In conclusion, the replacement of mineral N with manure under deficient irrigation provides a better fertilization strategy to maintain annual WUE of wheat-maize system, which has the potential to relieve the regional water scarcity for sustainable agriculture production in the North China Plain.