To explore the water and nitrogen transport characteristics under water and fertilizer integration of bubbled-root irrigation

through the indoor fertilizer infiltration test

the migration characteristics of wetting front migration

soil moisture

ammonium nitrogen and nitrate nitrogen were studied under different soil initial water content (4.13%

7.21%

11.06%

14.01%). The relationships between the cumulative infiltration amount

the wetting front migration distance and the soil initial water content of bubbled-root irrigation were established. An empirical model was proposed to calculate the cumulative infiltration volume and the wetting front migration distance under different initial water content. Results showed that: the cumulative infiltration

the wetting front migration distance

the moisture in the body

the distribution and transformation of nitrogen were all affected by the initial water content of soil. At the same time

the cumulative infiltration reduced with the increase of initial soil water content

while the wetting front migration distance increased with the increase of initial soil water content. The higher the initial water content of soil was

the larger volume of wetting body was

and the wilder water

ammonium nitrogen and nitrate nitrogen distributed. The closer to the emitter outlet

the contents of ammonium nitrogen and nitrate nitrogen in the soil were higher. The infiltration coefficient K decreased with the increase of initial soil water content

while the infiltration index α showed an opposite trend. The fitting parameters a and b of horizontal wetting front both increased with the increase of initial soil water content. The vertical downward wetting front migration index c increased with the increase of initial soil water content

while the infiltration index d decreased with the increase of initial soil water content. With the continuous redistribution of soil moisture distribution

the moisture distribution in the moist body was more uniform

and the uniformity of water distribution evaluated by Christiansen uniformity coefficient Cu

in moist body was 61.99%

74.27% and 83.60%

respectively

at the end of irrigation

redistribution of 1 day and 3 days. With the redistribution

the content of ammonium in the wetted body gradually decreased

but the distribution region of ammonium nitrogen was almost unchanged. With the redistribution

the distribution of nitrate nitrogen in the wetted area became larger

the average value of it increased

and the maximum value of it had a downward trend. The above research results can lay the foundation for further researches on water and nitrogen use efficient of bubbled-root irrigation technology.