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| Effects of soil bulk density on water and nitrogen transport characteristics under one-dimensional vertical infiltration of muddy water and fertilizer |
| BAI Rui,FEI Liangjun1,2*,CHEN Lin1,LIU Le1,ZHONG Yun1,LI Qiaoli1 |
| 1. Institute of Water Resources and Hydro-electric Engineering, Xi′an University of Technology, Xi′an, Shaanxi 710048, China; 2. Shaanxi Province Institute of Water Resources and Electric Power Investigation and Design, Xi′an, Shaanxi 710001, China |
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Abstract In order to reveal the effect of soil bulk density on water and nitrogen transport characteristics of muddy water and fertilizer infiltration, through the indoor soil column infiltration test, the cumulative infiltration, the wetting front migration distance, soil water content distribution and soil nitrate nitrogen transport characteristics were studied under different soil bulk densities(1.30, 1.35, 1.40, 1.45 g/cm3). The cumulative infiltration was fitted using the Philip infiltration model and capacitive charging empirical model. The relationships of cumulative infiltration and wetting front migration distance with soil bulk density were established, respectively. The results showed that for the same infiltration time the cumulative infiltration reduced with increasing soil bulk density, the higher the soil bulk density, the smaller the wetting front migration distance, and the narrower the distribution range of water and nitrate nitrogen in the wetted body. The cumulative infiltration of muddy water and fertili-zer infiltration conformed to the Philip infiltration model and capacitive charging empirical model. There was a significant power function relationship between wetting front migration distance and infiltration time. After the water supply was stopped, both of the soil water content and nitrate decreased with increasing infiltration depth. As the soil moisture was redistributed, the nitrate nitrogen content in the upper layer gradually decreased, but that in the lower layer gradually increased. After a redistribution for two days, the nitrate nitrogen content peaked near the wetting front, and the distribution of nitrate nitrogen content in the whole wetted body tended to be uniform. The results provide a basic reference for further study on nitrogen transport in the infiltration of muddy water and fertilizer.
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Received: 25 April 2019
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