Simulation Of Water And Nitrogen Use Efficiency And Migration In Saline Soil Of Southern Xinjiang

This paper set two different salinity levels,3 irrigation treatments(3500 m3.hm-2,4100 m3.hm-2,4700 m3.hm-2)and 3 nitrogen(160 kg.hm-2,260 kg.hm-2,360 kg.hm-2)of different water and nitrogen treatments,in southern area of different saline soil under different water and nitrogen treatment on cotton ecological indicators,water and nitrogen use the efficiency and migration of water and nitrogen affect the system research,simulation of soil moisture and nitrate dynamics,reveal the different salinization of soil water and nitrogen coupling mechanism and put forward the suitable for local water nitrogen production mode.In order to improve the southern area salinization cotton yield,water and nitrogen use efficiency,save water resources and provide theoretical basis for the prevention of environmental pollution,to improve salinized soil,has an important significance to prevent the occurrence of secondary salinization.The main conclusions of the experiment and simulation are as follows:1.The moderate saline soil was 2-3 days earlier than the mild saline soil,and there was no significant difference in the growth period of the cotton under W_HF_H treatment.The plant height increased gradually with the increase of nitrogen fertilizer and irrigation water,with the increase of salt stress of cotton plant height decreased,the same amount of nitrogen under the condition of influence on plant height of W_H>W_M>W_L.In the two salt soils,the proper water-saving nitrogen had little effect on the growth and development of cotton.Cotton stem diameter is not significantly affected by salt,stem diameter in high fertilizer and fertilizer is the highest,in the same nitrogen level on the stem diameter is W_H>W_M>W_L,the cotton stem diameter of the coupling of water and fertilizer W_HFM treatment reached the maximum.The leaf area index of plants in two different water and nitrogen treatments under the growth process of salt soil were increased first and then decreased,the same irrigation level of leaf area index influence the performance of the F_H>FM>FL,under the same nitrogen level on cotton leaf area influence degree is W_H>W_M>W_L.2.The change law of dry matter accumulation of cotton showed "S" type,two kinds of soil salinization in the same fertilization level,dry matter accumulation increased with the increase of irrigation amount,the cumulative increase of fertilizer to promote the dry weight of cotton under the same irrigation level,when the fertilizer amount reaches a certain degree,high fertilization the amount is not significant to affect the quality of dry cotton,the irrigation amount was 4700m3.hm-2when the nitrogen rate was 260 kg.hm-2 reached the maximum amount of dry matter accumulation of the formation of water and nitrogen coupling for the best W_HFM.3.Effects of salinity on yield is bigger,inhibited the growth of cotton,when the nitrogen amount was 260 Kg.hm-2,irrigation amount was 4700m3.hm-2 W_HFM treatment,seed cotton yield was the highest.The water and nitrogen use efficiency of cotton would be reduced when the irrigation amount was more than 4100m3.hm-2 and the amount of nitrogen was more than260 Kg.hm-2,that is,after W_MFM treatment,the water and nitrogen use efficiency of cotton was the best,and the water nitrogen coupling was W_MFM.In the two kinds of salinized soil,the nitrogen uptake of cotton plants was between 80 Kg.hm-2-350 Kg.hm-2 and 65.4Kg.hm-2-334.8Kg.hm-2,and the nitrogen fertilizer had the highest absorption and utilization rate under the condition of high nitrogen and water.4.The results showed that under W_MF_H treatment water downward migration significantly,soil moisture mainly distributed in 60-80 cm,the distribution of soil moisture at this time is more close to the cotton root distribution,thus more conducive to the absorption of water by cotton,predicted results show the lowest water content when soil water content reached 0.17cm3.cm-3 is consistent with the required rate of cotton seed germination for 0.168cm3.cm-3,and the water resource can be saved.Under W_HFM treatment,the peak value of nitrogen accumulation appeared at 60-80 cm,and the content of nitrate nitrogen in soil was close to the distribution position of the main root system of cotton,which contributed to the growth of cotton in this range.