| Numerical simulation of soil water and nitrogen distribution under the integration of drip irrigation and fertilization |
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| DOI：10.7606/j.issn.1000-7601.2019.02.02 |
| Key Words: drip fertilization water and nitrogen transport numerical simulation |
| Author Name | Affiliation | | LI Hui-xian | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas，Ministry of Education, Northwest A&F University,Yangling,Shaanxi 712100,China | | WANG Wen-e | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas，Ministry of Education, Northwest A&F University,Yangling,Shaanxi 712100,China | | HU Xiao-tao | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas，Ministry of Education, Northwest A&F University,Yangling,Shaanxi 712100,China |
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| Abstract: |
| In order to study soil water and nitrogen (N) transport and distribution under drip irrigation and fertilization, the soil water and N transport in the process of drip irrigation and redistribution was studied with a water and N infiltration experiment with soil column under drip irrigation. At the same time, the geometric model of water and N infiltration in soil column under drip irrigation was established by using HYDRUS software to simulate the soil water and nitrogen transport. The soil water content, ammonium nitrogen (NH+4-N), and nitrate nitrogen (NO-3-N) concentration collected at 12 observation points in the experiment and simulation were analyzed. The result showed that: the relative error between simulated and measured values of soil moisture content was less than 10%, and the simulated and measured values of NH+4-N and NO-3-N were less than 20%.At the end of drip irrigation, soil water content in soil profile decreased with the increase in distance from the emitter, and increased to 0.2 cm3·cm-3 in soil layer of 25~30 cm after 72 hours of redistribution. After 120 hours, soil water content in soil profile decreased by 18% compared with that at the end of drip irrigation. The content of NH+4-N was mainly distributed in the zone within 20 cm from emitter. The concentration of NH+4-N in soil reached the maximum value at 24 h and gradually decreased with time, and decreased by 40% at 120 h. The concentration of NO-3-N in soil increased gradually with time from 24 h to 120 h, and the concentration of NO-3-N increased from 0.442 mg·cm-3 to 1.2 mg·cm-3 in the zone of 20 cm from the emitter. At 24 h, the spatial distribution of soil NO-3-N concentrations was not significant, with the concentration of soil NO-3-N concentrations at observation points 1, 3, 6, 8, and 5 being 0.437, 0.467, 0.451, 0.482 and 0.447 mg·cm-3, respectively, the difference was less than 0.05 mg·cm-3. After 48 h, the spatial distribution of soil NO-3-N concentration in soil profile decreased with the increase in distance from the emitter, as the vertical distribution decreased 53% from observation point 1 that was 5 cm away from emitter to observation point 8 that was 25 cm away from the emitter. Based on the results, the numerical model can be used to simulate the soil water and N transport under drip irrigation and fertilization. |
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