Simulation of nitrate leaching under irrigated maize on sandy soil in desert oasis in Inner Mongolia, China

摘要

Water scarcity and nitrate contamination in groundwater are serious problems in desert oases in Northwest China. Field and p#eN microplot experiments with traditional and improved water and nitrogen management were conducted in a desert oasis in Inner Mongolia Autonomous Region. Water movement, nitrogen transport and crop growth were simulated by the soil-plant system with water and solute transport model (SPWS). The model simulation results, including the water content and nitrate concentration in the soil profile, leaf area index, dry matter weight, crop N uptake and grain yield, were all in good agreement with the field measurements. The water and nitrogen use efficiency of the improved treatment were better than those of the traditional treatment. The water and nitrogen use efficiency under the traditional treatment were 2.0kgmpd and 21kgkgp#, respectively, while under the improved treatment, they were 2.2kgmpd and 26kgkgp#, respectively. Water drainage accounted for 24-35% of total water input (rainfall and irrigation) for the two treatments. Nitrogen loss by ammonia volatilization and denitrification was less than 5% of the total N input (including the N comes from irrigation). However, 32-61% of total nitrogen input was lost through nitrate leaching, which agreed with the p#eN isotopic result. It is impetrative to improve the water and nitrogen management in the desert oasis.