Effects Of Soil Salinity And Fertigation Method On Growth And Fertilizer N Use-efficiency Of Cotton Under Film Drip Irrigation

The shortage of water resources and soil salinity are important limiting factors for agricultural production and environmental melioration in Xinjiang. The under-film drip irrigation has gained widespread popularity as a water saving and salinity control method and provided a research thinking for the rational development and utilization of saline soil. This study focus on soil salinity management and saline water reuse and sets out to address the relationship between the soil water, salt and nitrogen distributions and cotton root uptake compensatory effects, and those effects on the aboveground growth and yield of cotton. This study focuses on the fate and residue of nitrogen in soil– plant system by using the isotopic tracer technology.This study is constituted by a simulation experiment and a microplot experiment. In simulation experiment, we aimed to illustrate the distribution of water and nitrogen in soil affected by different fertigation methods with under-film drip irrigation. Meanwhile, using a 15N-labelling approach, the fate of nitrogen fertilizer in soil– plant system and effects on yield of cotton were studied in a field microplot experiment with different soil salinity and fertigation method treatments. The main results and conclusions were listed as follows:Fertigation methods had no effects on inorganic nitrogen content of soil, but affected the inorganic nitrogen transformation significently. The fertigation method that nitrogen applied at the end of the irrigation cycle has promoted nitrification of soil ammonium nitrogen.Root and aboveground dry matter weight of cotton were significantly affected by fertigation method and soil salinity. Dry matter weight and seed cotton yield were higher in 0.44 mS cm-1 than that in 0.26 mS cm-1, but reduced signifcently with 0.68 mS cm-1. The fertigation method that nitrogen applied in the beginning of the irrigation cycle increased dry matters accumulation and seed cotton yield.N accumulation and nitrogen fertilizer use efficiency (NUE) were significantly influenced by salinity, feritigation method and salinity×feritigation method interaction. At low salinity, the highest of N accumulation and NUE were found in the fertigation method that nitrogen applied in the beginning of the irrigation cycle. At higher salinity, the fertigation method that nitrogen applied at the end of the irrigation cycle increased the N uptake and NUE.