Nitrogen reduction by 20 % with green manure retention reduces soil evaporation, promotes maize transpiration and improves water productivity in arid areas

Abstract

ContextThe contradiction between high agricultural yields and water resource shortages is becoming increasingly serious. Reducing nitrogen appropriately with green manure retention can ensure high agricultural yields, but it remains unclear whether it can optimize crop water consumption characteristics and improve water productivity (WPc). ObjectiveThis study aims to investigate the effect of green manure retention combined with nitrogen reduction on water use characteristics of maize and its potential mechanisms. MethodsA field experiment was conducted at Wuwei Oasis Agricultural Experimental Station in China from 2020 to 2022, with five treatments: (i) traditional nitrogen application with green manure retention (N100), (ii) nitrogen reduction by 10 % with green manure retention (N90), (iii) nitrogen reduction by 20 % with green manure retention (N80), (iv) nitrogen reduction by 30 % with green manure retention (N70), and (v) nitrogen reduction by 40 % with green manure retention (N60). ResultsThe results showed that compared with the N100 treatment, 0−50 cm maize root biomass (RB), biomass accumulation (BA), and canopy cover (CC) were not significantly reduced in the N80 treatment. This model ensured a stable grain yield (GY) and improved 0−50 cm soil water storage (SWS) by 7.1−13.1 %. It effectively suppressed soil evaporation (E), promoted maize transpiration (T), reduced maize evapotranspiration (ET) by 4.8 %, and increased WPc by 1.8−26.6 %. Structural equation modeling (SEM) suggests that RB was the most important factor for improving WPc. In addition, this system ensures that economic benefits did not decrease. ConclusionIt can be seen that nitrogen reduction by 20 % with green manure retention is a reasonable nitrogen fertilizer management system to alleviate the contradiction between high maize yield and water resource shortages in the region. ImplicationsThe results of this study provide valuable insights into alleviating the contradiction between agricultural production and regional water resource scarcity.