The Effects Of Water And Fertilizer Regulation Strategy On Cotton Canopy Structure And Soil NO₃^--N Leaching Under Mulch-film Drip Irrigation

This articler explores the typical arid area in Xinjiang Korla cotton over the field experiment to study the drip irrigation of cotton in water and fertilizer regulation strategy at each growth stages of top dressing and irrigation water, the number of water and fertilizer regulation strategies on canopy structure characteristics and soil NO3--N leaching and yield, and clear relativity of canopy structure indexes and soil NO3--N and refinement of water and fertilizer regulation for drip irrigation of cotton irrigation and fertilization techniques to improve and enhance the efficiency of fertilizer use for reference. Draw the following conclusions:(1) Under conventional irrigation (4800m3·hm-2) conditions, the conventional fertilization strategy (each growth period supplemental proportion of6.3%,8%,8%,9.7%,15%,6.7%) can make the cotton LAI value significantly increased and increase MFIA value, TC value and T value significantly reduced and increase K value. The conventional fertilization strategy can make seed cotton yield significantly increased, and make the0～100cm NO3--N quantity of soil significantly increased.(2) Under conventional fertilization conditions, optimizing irrigation strategies (4200m3·hm-2) to obtain the largest cotton LAI value, TC and T values at a low level, and make the cotton seed cotton yield significantly increased, at the same time for the reduction of soil NO3--N to the lower leaching have obvious effect.(3) Under optimization irrigation (4200m3·hm-2) conditions, the reducing N fertilization strategy (each growth stages supplemental proportion of8%,10%,22%,25%,15%) to obtain the optimum LAI and MFIA values, and TC, T and K values at a lowest level, and making it the highest relative seed cotton yield of5527.76kg·hm-2and to more effectively reduce soil NO3--N accumulation.(4) The different effects on NO3--N quantity of soil of the soil profile under the different water and fertilizer regulation strategy. In full growing period,0～100cm NO3--N quantity of soil higher in the early flowering and boll stage, and lower in the flowering, blooming and boll opening period. The vertical direction, the NO3--N quantity of soil go down with the soil depth in0～100cm. When the first decreases and then increases and then decreases of the NO3--N quantity of soil is gradually in full growing period, and the increase of nitrogen, the same level of the NO3--N quantity of soil was increased.(5) There were significant correlations between cotton canopy structural characteristics of each index (LAI, MFIA, TC, T values). The cotton leaf area index (LAI) is better than the other index reflect the soil NO3--N accumulation levels. Growth period of soil NO3--N accumulation reflects the sensitivity of the level of irrigation and fertilizer higher than the sensitivity of the leaf area index.