In order to improve the utilization efficiency of water and nitrogen in the red soil under surge root irrigation

through an indoor fertilizer infiltration test

the soil infiltration capacity

wetting front migration

soil moisture

and the migration characteristics of ammonium nitrogen and nitrate nitrogen were studied under different fertilizer concentrations (0

10

20

35

60 g/L)

and the relational model between cumulative infiltration volume

the wetting front migration distance and the fertilizer concentration were established. The results showed that:The cumulative infiltration volume

the wet front migration distance

and the migration and distribution of water and nitrogen in the wet body were all affected by the fertilizer concentration. At the same infiltration time

the cumulative infiltration volume and the wet front migration distance all increased with the increase of the fertilizer concentration

and they all had a power function relationship with the infiltration duration. At the end of irrigation

the greater the concentration of fertilizer was

the greater the soil moisture content was

and the greater the concentration of ammonium nitrogen and nitrate nitrogen was for the same soil depth

and the distribution of nitrate nitrogen was wider than ammonium nitrogen. With the redistribution of fertilizer solution

the position of maximum moisture content went down gradually

and the distribution of moisture content was more uniform. The changes of ammonium nitrogen and nitrate nitrogen concentration were different between the shallow and deep layer of soil. In the shallow layer

the concentration of ammonium nitrogen gradually decreased

while the concentration of nitrate nitrogen decreased first and then increased. In the deep layer

the concentration of ammonium nitrogen increased first and then decreased

while the concentration of nitrate nitrogen showed a gradually increasing trend. The research results could provide a theoretical reference for further study on the nitrogen transport and transformation of surge-root irrigation in the red soil region.