Evaluation Of Soil Eco-hydrological Effects Under Different Crop Planting Structures In Guanzhong Area,Shaanxi

The shortage of water resources has become a bottleneck in the current agricultural development in the Loess Plateau.How to deal with the shortage of cultivated land resources and the low quality of cultivated land is the key to rational allocation of limited water resources and improving water resource utilization efficiency.Among them,the soil eco-hydrological effects can reflect the dynamics of water in the soil to a certain extent,and reveal the interaction between plants and soil through the characteristics of water flow and utilization.In this study,different crop planting structures(wheat（Xiaoyan 22）,soybean（Baodou 6）,alfalfa（Suntory）,alfalfa-corn（Jingke 932）,alfalfa-corn（Heyu 9566）,alfalfa-corn（Dika 625）,maize（Zhengdan 958）,and maize（Huamei 1）were selected as the research objects to study the soil ecological and hydrological characteristics,explore the influence of crop planting structures on the soil ecological and hydrological characteristics,and construct a decision-making model to study the optimal crop planting structure in Guanzhong,Shaanxi using the analytic hierarchy process（AHP）.Results of this study will provide a basis for understanding the driving mechanism of water cycle in soil-plant system and the guidance for selecting crop planting structure and optimizing water management in the Loess Plateau.The results are given below.1.The soil water content,soil bulk density,capillary porosity and non-capillary porosity of different crop planting structures are significantly different（P<0.05）,while the soil mechanical composition and total soil porosity of different crop planting structures are not significantly different.The specific performance is:the average soil water content of wheat（Xiaoyan 22）is 16.26%,and the lowest soil water content of alfalfa（Suntory）is 14.06%.There is a negative correlation between bulk density and total porosity.Compared with the other seven planting structures,the wheat（Xiaoyan 22）planting structure has poor soil development.2.The different planting structures had significant influence on soil organic matter and total nitrogen content.The soil organic matter and total nitrogen content in the same layer of soil of alfalfa（Suntory）and alfalfa-maize were significantly higher than those of other planting structures（P<0.05）.3.Corn（Zhengdan 958）had the strongest field water holding capacity（average field water holding capacity was 64.80 mm）,and wheat（Xiaoyan 22）had the highest average soil water holding capacity of 25.18 mm.The soil water storage capacity of the 8 planting structures in the 30-100 cm soil layer was significantly higher than that of the 0-30 cm soil layer.The changes of soil maximum water storage capacity and maximum retention water storage capacity were basically the same as the changes of soil capillary porosity and non-capillary porosity.The chloride ion concentration in the soil of different planting structures ranged from 0.02 g·kg^-1to 0.09 g·kg^-1.Wheat（Xiaoyan 22）had the highest average soil chloride ion concentration(0.07 g·kg^-1)and the lowest soil water deficit（58.98%）;soybean（Baodou 6）had the lowest average soil chloride ion concentration(0.03 g·kg^-1).4.Select soil water content,bulk density,total porosity,capillary porosity,non-capillary porosity,organic matter,total nitrogen,field water holding capacity,soil water storage capacity,maximum water storage capacity,maximum retention water storage capacity,saturated water storage capacity,chloride ion and water deficit are the evaluation indicators,and the indicators with the largest weight values are non-capillary porosity（0.29394）,maximum retained water storage（0.280034）,and chloride ion concentration（0.088947）.The hydrological and ecological effects of different crop planting structures are evaluated.It is calculated that the comprehensive evaluation value of alfalfa（Suntory）is 0.1381,followed by alfalfa-corn（Heyu 9566）is 0.1346,and wheat（Xiaoyan 22）is the lowest 0.0822.To sum up:in the Guanzhong area of Shaanxi,alfalfa（Suntory）and alfalfa-corn（Heyu 9566）are relatively suitable crop planting structures.Weighing economic and ecological benefits,it is recommended to adopt alfalfa-corn intercropping mode to realize the optimal allocation of agricultural planting.