Soil Water And Salt Distribution Under The Condition Of Underground Drainage And Field Experiments Of Crop Growth

It is important for reasonable arrange of the underground drainage pipes and effective prevention of soil salinization to study soil water and salt distribution as well as the crop growth under subsurface pipe drainage in local farmland,which also with great significance for sustainable development of agriculture in the research area.In this paper,a typical research area was selected in Yongji Experimental Base of China Agricultural University in Yongji Irrigation Region of Hetao Irrigation District it was selected to carry out a two-year experiment and simulation study on soil water and salt distribution as well as crop growth in farmland under the condition of pipe drainage.The main conclusions are as follows:(1)During the experimental observation period,the soil water and salinity content of different irrigation quotas under the pipe drainage conditions are generally varied with the similar trend.The soil water content increased with soil depth,and drastically changed at the surface layer of 0-20cm,and it maintained at saturated water content in the depth of 100cm.The soil salinity content decreased with soil depth,it was high in 0-10cm surface soil and showed as obviously salt accumulation phenomenon.The salt content became basically stable at 1.0g/kg in 100 cm soil,which indicates that the subsurface pipe drainage has a great effects on soil water and salt distribution.(2)The variation of groundwater level was similar in different research areas.Generally,the groundwater level can drop to 1.20-1.50 m within 1-2 days after irrigation or rainfall.The salinity of groundwater in the research area has little change with time,but showed high spatial variation degree.According to the analysis of daily drainage intensity,the drainage volume of underground pipes was greatly affected by soil texture.Moreover,the higher the clay content in soil,the weaker the pipe drainage effect and the higher the mineralization degree of groundwater.(3)There is no significant difference in the main growth index and yield of crops between different condition of pipe drainage.The crop yield is relatively higher with the irrigation quota of 75mm.(4)The DRAINMOD 6.1 model is calibrated and verified by using the experimental observation data of groundwater depth in 2018.The results showed that the measured value and the simulated value of groundwater level are well fitted,and the model can be initially used to simulate and analyze the variation rule of groundwater depth in this study area.