Effect Of Different Infiltration Water On Soil Preferential Flow Movement In Sugarcane Field Of Guangxi

In order to explore the influence of infiltration water amount on the change characteristics of preferential flow movement of farmland soil,this study took sugarcane field in Guangxi as the research object,and simulated moderate rain,heavy rain and rainstorm rainfall intensity under natural conditions through staining tracer test,radar detection test and soil column water infiltration test.Soil water movement under16 mm infiltration water（moderate rain）,35 mm infiltration water（heavy rain）and 70mm infiltration water（torrential rain）was analyzed.Image information interpretation and multivariate statistical analysis were used to reveal the change characteristics of soil preferential flow movement under different infiltration water in sugarcane field,which provided scientific suggestions for improving water and fertilizer utilization efficiency in sugarcane planting.The results are as follows:（1）The spatial distribution of preferential flow in sugarcane field soil under different infiltration amounts is as follows.In 0-50 cm soil space,the average maximum infiltration depth of 70 mm infiltration amount（19.43 cm）is 1.72 and 2.51 times that of 35 mm infiltration amount and 16 mm infiltration amount,respectively.The average total dyeing area ratio was 70 mm infiltration water（20.10%）,35 mm infiltration water（14.43%）,16 mm infiltration water（10.92%）,and there were significant differences among them（P<0.05）.In the range of 0-50 cm soil depth,the spatial variation coefficient of dyeing area ratio was the smallest（0.84）under 70 mm infiltration water,and the largest（0.93）under 35 mm infiltration water in sugarcane field.The increase of infiltration water will reduce the non-uniformity of spatial distribution of preferential flow,and the spatial distribution level of preferential flow is higher in the sugarcane field under torrential rain intensity.（2）The water content at different soil depths increased with significant difference（P<0.05）,indicating that external water supply could significantly affect the water movement in soil.The discharge velocity of soil column under 70 mm infiltration water is the fastest,and the undisturbed soil column under 16 mm infiltration water reaches the stable discharge at the earliest.The absolute value of slope of soil conductivity curve is maximum when the outflow time is 0-20 min.The migration coefficient can reflect the movement degree of soil preferential flow,and the variation range of the migration coefficient of the sugarcane field soil profile under 70 mm infiltration water volume is the largest,indicating that the spatial movement of soil preferential flow under the intensity of heavy rain is the most severe.（3）There was a significant correlation between the maximum amplitude and the spatial variation coefficient of staining area ratio（P<0.05）.The fluctuation degree of electromagnetic wave amplitude can reflect the water movement in soil.The fluctuation of electromagnetic wave amplitude of 16 mm infiltration water in 0-20 cm soil depth is the most obvious,and the fluctuation of electromagnetic wave amplitude of 35 mm infiltration water in 0-30 cm soil depth is-3×10⁶～4×10⁶ m V·m^-3.When the infiltration water of 70 mm is within the range of 30-50 cm soil depth,there is still a large connected color change zone in the radar profile image.The maximum time interval was the smallest,the amplitude ratio was the largest,and the development degree of soil preferential flow was the highest.