Soil water and nitrogen distributions as effected by different irrigation and nitrogen applied by lateral move sprinkler system in the semi-arid region

摘要

This study was aimed at providing an optimal management practice of irrigation and fertilization for sprinkler irrigation of maize. Field experiments were conducted on a very coarse sandy soil irrigated by a one-span lateral move sprinkler system in semi-arid region of Inner Mongolia Autonomous Region during the growing seasons of maize in 2012 and 2013. Three irrigation application rates of 40%, 70%, and 100% of full irrigation that was determined by evapotranspiration (ETC) requirements were used in 2012, whereas four levels of 40%, 70%, 100% and 130%, of ETC were tested in 2013. Four nitrogen application rates of 80, 160, 240, and 320 kg ha~(-1) were evaluated in both growing seasons. A greater irrigation level resulting in a layer wetted depth of soil following an irrigation event. The distributions of nitrate nitrogen (N03'-N) in the soil resulted from different irrigation and fertilization regimes varied temporally and spatially during the growing seasons. A larger amount of nitrogen appliedproduced a significantly greater N03'-N content in the 0-100 cm soil layers. For a given nitrogen application rate, a lower irrigation level tended to retain more N03'-N in the root zone at the end of the growing season. Yield and nitrogen agronomic efficiencies (MAE) increased significantly with an increasing irrigation level when irrigation level was between 40% and 100% of ETC. However, a reduced yield and NAE was observed when the irrigation level exceeded 100% ETC. Nitrogen application rate of 160kg ha~(-1) (N2) obtained an acceptable high yield and NAE at full irrigation. For the very coarse sandy soil, we recommended a management practice of 100%, ETC and nitrogen application rate of 160 kg ha~(-1) under sprinkler irrigation in semi-arid regions to obtain high yield and NAE while reducing the risk of nitrate leaching.