Effects of Water and Nitrogen Coupling on Water Consumption and Soil Moisture of Isatis indigotica

Water and nitrogen coupling is the key technology for efficient water saving and nitrogen reduction of Isatis indigotica.The study on effects of water and nitrogen coupling on water consumption and soil moisture dynamic changes of Isatis indigotica provided theoretical guidance for efficient water and fertilizer management.In 2018 and 2019，an experimental study on water and nitrogen coupling of Isatis indigotica was carried out in Yimin Irrigation Experimental Station，Minle County，Zhangye City，central Hexi Corridor.Results showed that，soil water storage in 0～160 cm soil layer showed a zigzag decreasing trend during growth and development of Isatis indigotica.Soil water storage decreased with increase of irrigation amount.Appropriate increase of nitrogen fertilizer could reduce consumption of soil water storage，excessive nitrogen increased consumption of soil water storage，and there was a significant interaction between irrigation and nitrogen application.Total water consumption of high water and low nitrogen（W3N1）treatment was the highest，with the values of 442.2～442.8 mm.Total water consumption of low water and medium nitrogen（W1N2）treatment was the lowest，and total water consumption in medium water and medium nitrogen（W2N2）and high water and high nitrogen（W3N3）decreased by 13.7%～14.8%.Water saving and nitrogen reduction could reduce consumption of soil water storage and water consumption during growth period of Isatis indigotica，which was conducive to virtuous cycle of water and nitrogen in crop-soil water system.