In order to study the effect of nitrogen application on the infiltration and water and salt transport in salt and alkali soil

the saline soil with salt content of 0.3%

0.9% and 1.2% and four different nitrogen concentrations (0

300

600

900 mg/L) were combined as the treatments

and one dimensional vertical soil column infiltration experiment were carried out. The results showed that:(1) Nitrogen application reduced the infiltration of saline alkali soil. Under the same nitrogen application level

the infiltration capacity of saline alkali soil decreased with the increasing of salt content

and the desalting depth also decreased. (2) With the increase of infiltration time

the soil moisture of the lower root zone was the maximum when no nitrogen was applied

and the water retention of soil was the best at this time. (3) In the saline soil with salt content of 0.3%

the amount of desalination in the soil with nitrogen application was larger than that without nitrogen application

and the nitrogen application promoted the desalination of saline alkali soil; however in saline alkali soil with salt content of 0.9% and 1.2%

the amount of desalination was higher when there was no nitrogen application

which mean that nitrogen application had an antagonistic effect on the desalination of saline alkali soil. The research results provided an effective mechanism foundation for rational nitrogen application in saline alkali soil

and provided reference for crop growth and ecological protection in salinized area.