Study Of Water And Nitrogen Coupling Effection On Spring Wheat Yield And Soil Fertilizer Distribution Under Drip Irrigation

Spring wheat under drip irrigation was widely planted in north Xinjiang. It developed rapidly in Kuitun city and Shihezi city as showed a remarkable effect on water-saving. Water and fertilizer, which can increase wheat yield and water and fertilizer the utilization efficiency, are the basic substance for the growth of wheat. Water and fertilizer coupling synergistic effect is obvious. Drip irrigation can supply water and nitrogen for spring wheat according to the situation of soil, climate and crop growth. To explicit the role of two-way drive function between water and fertilizer is one important issue for the agriculture development. In this paper, In order to find suitable Nitrogen level for spring wheat of drip irrigation in Xinjiang and improve efficient utilization of water and fertilizer, the field experiment on spring wheat was conducted with different water and fertilizer treatments, which aimed to analysis the plant growth, yield, soil moisture profile, nitrate-N transport and total nitrogen absorption. The mainly results is as follows:(1)Water-nitrogen coupling had a significant effect on wheat growth index and yield. Between irrigation and nitrogen rate were interaction and promotion. In the condition of suitable irrigation and nitrogen rate, wheat growth index and yield increased with the increase of irrigation and nitrogen rate. The plant height of wheat was largest under high water and fertilizer treatment, leaf area and leaf dry matter accumulation changed similarly, and the relationship presented approximate parabola. The maximum chlorophyll content appeared with the intermediate water and fertilizer treatment, with the high water and middle fertilizer treatment, the dry matter quality accumulation of per plant was maximum(4.206 g), panicle dry matter accumulation of middle water and nitrogen treatment was maximum(2.750 g). Effect of water and nitrogen coupling on wheat grain number per spike and yield less than 1000 grain weight, but it still showed significant correlation. Suitable irrigation and nitrogen treatment had the highest yield 6891.44 kg perhectare.(2)Water and nitrogen significantly affect water distribution of different soil layers and profile. Root moisture absorption increased when the amount of nitrogen fertilizer promoted. In the growth period, water distribution changes larger in such soil layers as 0-20 cm and 20-40 cm. Soil moisture in 0-20 cm soil layers mainly affected by irrigation, rainfall and crop uptake while in 20-40 cm relatively small. Soil profile moisture distribution gap between the different treatments was small in the early stage, increasing with irrigation fertilization increased, and decreased finally. Under the same irrigation, soil moisture decreased with the amount of nitrogen increase.(3) Spring wheat’s absorption of total nitrogen and the soil nitrate-N accumulation were greatly affected by water and nitrate fertilizer coupling. Nitrate content in soil decreased with irrigation amount increased. Irrigation mainly impacted soil nitrogen content during 0-20 cm lawyers in three leaf period. Vegetative growth increased in jointing and heading period. The soil nitrate-N content increased during the jointing stage under low water and middle water treatment in 0-20 cm soil layer, high water treatment in 60-80 cm soil. In heading stage, soil nitrate accumulated only in 40-60 cm under low water treatment. Under the same irrigation soil nitrate-N accumulation increased with nitrogen application increased in 0-40 cm soil, while nitrogen rate decreased with irrigation increased. As under high water deal nitrate content decreased in 40-80 cm soil, there was leaching of nitrogen. Irrigation and nitrogen fertilizer both influenced plant total N accumulates significantly. Nitrogen fertilizer affect more significantly than irrigation. Water and nitrogen coupling corresponding is significant. The largest amount of spike TN in leaves, stems, and the cumulative was separately under high water and nitrogen treatment 17.88 mg per plant, high water and nitrogen treatment processing 28.05 mg per plant, middle water and nitrogen treatment processing 107.16 mg per plant.(4)With Matlab software, yield equation with irrigation and nitrogen fertilization of spring wheat was fitted through three-dimensional surface fitting. The model of actual yield and yield-related simulation provide a reference for the spring wheat yield prediction under the experimental conditions. The equation indicating that the single factor promotes yield increasing, and excess irrigation and nitrogen fertilizer amount is not conducive to increase yield. Through the simulation equations obtained the highest yield solutions that with irrigation 493.39 mm, nitrogen fertilizer 294.38 kg perhectare, to achieve maximum yield 6954.62 kg perhectare.