Optimizing brackish water and nitrogen application regimes for soil salinity, yield, fertilizer and water productivity of a mulched drip irrigated cotton cropping system

Abstract

ContextBrackish water irrigation poses a threat to the sustainability of irrigated dryland crop systems, making it essential to identify effective water and nutrient management regimes to mitigate salt impact on agriculture. ObjectiveThis project is focused on determining the optimal combination of brackish irrigation water and nitrogen application in the mulched drip irrigation cultivation system for cotton crops in Xinjiang. MethodsThe combined effects of three brackish water irrigation amounts (I) (I1, 337 mm; I2, 412 mm; and I3, 562 mm) and three nitrogen application levels (N) (N1, 160 kg ha−1; N2, 315 kg ha−1; and N3, 395 kg ha−1) were investigated on soil salinity, cotton (Gossypium hirsutum L.) growth, nitrogen fertilizer and water productivity under mulched drip irrigation. The experiment was conducted over two growth cycles using a split-plot design with three replication treatments, with I arranged in the main plots and N in the subplots. ResultsResults indicated that irrigation amount, nitrogen application level, and their interaction significantly affected soil salt accumulation, cotton shoot biomass and yield, cotton nitrogen uptake (NU), nitrogen partial factor productivity (NPFP), and water productivity (WP). Additionally, the main effect year had a significant effect on all study variables, with higher values observed in 2017 compared to 2016, except for soil salt accumulation. The highest cotton shoot biomass, yield, NU, and WP as well as the lowest soil salt accumulation in mulched strips were both obtained in the I2N2 treatment. ConclusionThis treatment can be an optimal water and nitrogen management strategy for the cotton planting system under mulched drip irrigation and is crucial for achieving water and fertilizer savings in dryland conditions with brackish water irrigation.