| In this paper,two years of field experiments were carried out in the Yongji irrigation field to explore the effects of different brackish drip irrigation systems and different growth periods on soil water,salt and crop growth,and IsoSource model to determine different potential water sources.Contribution rate to the growth of corn crops.Comprehensive soil water and salt characteristics,water use efficiency,desalination rate and various growth indicators of maize proposed a salty drip irrigation and leaching system suitable for the arid area of Hetao,which provided local irrigation for brackish water and prevented secondary salinization of soil.A certain theoretical basis.The main findings are as follows:(1)The water content of soil 0?40cm soil layer is significantly higher than 40?100cm water content 6.5%.The soil moisture content of 0?60cm and 60?100cm increased by 18.90%and 14.28%after leaching in different growth stages,and the soil moisture content of 0-40cm was significantly higher than that without rinsing after jointing,tasseling and filling.(CK)treatment,the maintenance time was 12d,25d and 28d respectively.(2)During the harvest period,the soil treated with brackish water showed different degrees of salt accumulation.The larger the irrigation quota,the more salt accumulation.The average salt accumulation rate of 0?40cm in each treatment was 6.36 times of freshwater treatment,and the average salt accumulation rate of 60-100cm was fresh water.5.95 times processed.The desalting effect of the soil after washing with different washing time was obvious.The salting rate of the salt after 0?60cm leaching was 55.01%higher than that of the salty water drip.Compared with the non-leaching treatment,the salt elution rate was average.Increased by 125.79%.The extra-membrane desalination rate,for example,increased by 38.90%in the membrane.The optimum salt-leaching effect at different growth stages was 54.78%.(3)Using the stable isotope simulation of rainfall and hydrogen in the test area of 2017 and 2018,the local atmospheric precipitation line equation is ?D=6.3138?18O-15.937.Based on the direct analysis of soil water and crop stem water isotope,the main water absorption depth of maize roots was derived,and the soil water contribution rate of different soil layers was obtained by using IsoSource model.It is concluded that the reduction of irrigation amount will lead to an increase in the contribution rate of deep soil water,and deepen the absorption and utilization of deep water by corn.After each irrigation,the utilization rate of irrigation water in corn roots increased significantly,and the response time was correlated with irrigation amount.In the later stage of growth,shallow groundwater would replenish soil water,and the contribution rate averaged 8.30%.(4)The yield of freshwater treatment was 1.5%higher than that of brackish water,and the difference was not significant(P>0.05).The water treatment in brackish water with different irrigation quotas was the highest.Compared with the non-leaching treatment,the yields of the different rinsing times were significantly increased by 18.8%and 8.1%(P<0.05),and the leaching yield during the filling stage was not significantly increased.After rinsing,the water storage capacity and water consumption of each treatment increased significantly.The effect of leaching at different growth stages on the water consumption of drip irrigation farmland was:treatment in the filling stage>treatment in the tassel stage>jointing stage treatment.Drip irrigation in brackish water combined with joint irrigation and leaching treatment,that is,8 times in the whole growth period.The irrigation quota is 15m3/mu,and the leaching quota at jointing stage is 70m3/mu,which not only improves crop yield but also reduces the risk of secondary salinization of soil.It is the optimal irrigation system for brackish drip irrigation and leaching in Hetao irrigation area. |
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