Research Of Efficient Water And Fertilizer Utilization Mode For Mechanically Havested Cotton With Film-mulched Drip Irrigation In Southern Xinjiang

As the leading industry of agricultural industrialization in Xinjiang,cotton industry plays an vital role in regional economic development.Problems such as extensive application of water and fertilizer and soil salinization have became important factors limiting local cotton production and sustainable agricultural development.How to achieve the goal of saving water and reducing salt by formulating scientific water and fertilizer application strategies has become a research hotspot in related fields.Aiming at the problems of soil secondary salinization and water and fertilizer management in cotton field under-mulch drip irrigation in southern Xinjiang,to improve the soil and water environment of farmland and ensure cotton production,the effects of different water and fertilizer combinations on cotton growth,yield and water and fertilizer use efficiency were explored.The split zone design of 4irrigation amounts（I0.6,I0.8,I1.0,I1.2）for the main treatment and 3 fertilizer quotas（F6,F8,F10）for the secondary treatment were set.Taking the treatment I1.0F12(irrigation amount of 450 mm and the fertilizer quota of 1260 kg·hm^-2)as the control,an integrated study was carried out on the cotton field in southern xinjiang.The main research results showed that:（1）With the increase of irrigation amount,cotton plant height and LAI first increased and then decreased,and were positively correlated with fertilizer quota,but excessive fertilizer would lead to premature senescence of leaves.Treatments of I0.8F8 and I1.0F10 were conducive to the construction of high-yield plant types,and promoted nitrogen absorption and the formation of photosynthetic products.The response of aboveground biomass of cotton to irrigation and fertilizer was different at different growth stages,and water and fertilizer treatment had no significant effect on the proportion of photosynthetic products transferred to reproductive organs.Overall,the increase of irrigation and fertilizer quota reduced the root-shoot ratio of cotton,which was not conducive to the improvement of water and fertilizer efficiency.（2）With the increase of irrigation and fertilizer quotas,the yield of seed cotton increased and then decreased,and reached the maximum yield at I1.0F10 level,which was 7680.91 kg·hm^-2.Excessive irrigation or fertilizer not only leaded to late maturity of cotton,which was not conducive to cotton yield increase,and would also inhibit the improvement of cotton fiber quality.According to the nutrient accumulation and distribution of cotton at the end of flowering and boll stage,I1.0 irrigation level was beneficial to the absorption and utilization of cotton nutrients.The theoretical analysis showed that the irrigation quota was 270⁴20 mm and the fertilizer quota was 630⁸70 kg·hm^-2,which could achieve higher water and fertilizer use efficiency.（3）The water consumption of cotton during the whole growth period was between 390 mm and690 mm,and I1.0 can basically met the water demand during the growth period of cotton,while F10can basically meet the nutrient demand of cotton at different irrigation levels.After irrigation,the increase degree of soil moisture increased with the increase of irrigation quota,and the soil moisture decreased gradually with the increase of distance from drip-tape,while the distribution of soil salinity was contrary to it,which was characterized by salt accumulation in deep soil layer and membranes.Combined with irrigation experiments in two growing seasons,in order to prevent secondary salinization of soil,the irrigation amount of cotton should be no less than 400 mm.In this experiment,soil salinity increased by 3.0%and-23.3%respectively in the main root area of I1.0 and I1.2 at the end of growing period,which was beneficial to prevent and control soil salinization.However,the changes of soil salinity under different water and fertilizer treatments were greatly affected by the basal value of soil salinity,so it is difficult to quantify the changes during the growth period.（4）Treatment I1.0F10(the irrigation amount was 450 mm in the growth period,8 d and 6 d irrigation interval for the budding and flowering stage respectively;the fertilizer in the whole growth period was 1050 kg·hm^-2)had the highest yield of seed cotton,which was treated in 2018,reaching7680.91 kg·hm^-2,WUE_ET and PFP were 1.49 kg·m^-3 and 7.32 kg·kg^-1,respectively,and the soil salinity increased less during the growth period.Compared with the control,fertilizer was saved by 20.0%and yield increased by 7.9%.It is an efficient application mode of cotton with high yield,water and fertilizer to ensure the sustainable development of agricultural water and soil environment in southern Xinjiang.