title: Modeling nitrate leaching and optimizing water and nitrogen management under irrigated maize in desert oases in Northwestern China.
abstract: Understanding water and N transport through the soil profile is important for efficient irrigation and nutrient management to minimize nitrate leaching to the groundwater, and to promote agricultural sustainable development in desert oases. In this study, a process-based water and nitrogen management model (WNMM) was used to simulate soil water movement, nitrate transport, and crop growth (maize [Zea mays L.]) under desert oasis conditions in northwestern China. The model was calibrated and validated with a field experiment. The model simulation results showed that about 35% of total water input and 58% of the total N input were leached to <1.8 m depth under traditional management practice. Excessive irrigation and N fertilizer application, high nitrate concentration in the irrigation water, together with the sandy soil texture, resulted in large nitrate leaching. Nitrate leaching was significantly reduced under the improved management practice suggested by farm extension personnel; however, the water and nitrate inputs still far exceeded the crop requirements. More than 1700 scenarios combining various types of irrigation and fertilizer practices were simulated. Quantitative analysis was conducted to obtain the best management practices (BMPs) with simultaneous consideration of crop yield, water use efficiency, fertilizer N use efficiency, and nitrate leaching. The results indicated that the BMPs under the specific desert oasis conditions are to irrigate the maize with 600 mm of water in eight times with a single fertilizer application at a rate of 75 kg N ha(-1).
authors.affiliation: Department of Soil and Water Sciences, China Agricultural University, Beijing 100193, People's Republic of China.
authors.forename: Kelin
authors.initials: K
authors.lastname: Hu
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.forename: Weiping
authors.initials: W
authors.lastname: Chen
authors.forename: Deli
authors.initials: D
authors.lastname: Chen
authors.forename: Yongping
authors.initials: Y
authors.lastname: Wei
authors.forename: Robert
authors.initials: R
authors.lastname: Edis
authors.forename: Baoguo
authors.initials: B
authors.lastname: Li
authors.forename: Yuanfang
authors.initials: Y
authors.lastname: Huang
authors.forename: Yuanpei
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000383:Agriculture; D002138:Calibration; D002681:China; D003889:Desert Climate; D008956:Models, Chemical; D009566:Nitrates / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis*; D014867:Water / Q000032:analysis*; D014872:Water Movements; D003313:Zea mays
chemical_list: D009566:Nitrates; D014867:Water; D009584:Nitrogen