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| Impact mechanism of water and fertilizer changes on groundwater nitrate nitrogen in newly cultivated rice fields |
| Received:July 25, 2024 |
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| KeyWord:rice field;groundwater nitrate nitrogen;soil nitrate nitrogen;water and nitrogen combined application;yield |
| Author Name | Affiliation | E-mail | | FENG Ning | College of Ecology and Environment, Ningxia University, Yinchuan 750021, China | | | GUAN Jiarong | College of Ecology and Environment, Ningxia University, Yinchuan 750021, China | | | ZHONG Yanxia | College of Ecology and Environment, Ningxia University, Yinchuan 750021, China
Key Laboratory of Restoration and Reconstruction of Degraded Ecosystems in Northwest China, Ministry of Education, Yinchuan 750021, China
State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China, Yinchuan 750021, China | zhongyx_w@163.com | | FENG Bo | School of Civil and Hydraulic Engineering, Ningxia University, Yinchuan 750021, China | |
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| Abstract: |
| Rice cultivation in the Yinchuan Plain oasis of Ningxia is highly intensive. In order to find an optimal water and fertilizer treatment mode, the effects of different irrigation amounts（200, 300 mm and 400 mm, denoted as W1, W2 and W3, respectively）and nitrogen application（0, 250, 370 kg·hm-2 and 490 kg·hm-2, denoted as CK, N1, N2 and N3, respectively）on NO3--N accumulation in groundwater, NO3--N accumulation in 0-80 cm soil, and rice yield and soil water content in newly reclaimed sandy farmland of Xidatan Qianjin farm, Pingluo County, Shizuishan City, China, were studied through the systematic study of a large-field experiment. The results showed that groundwater NO3--N concentration increased with increasing irrigation at the same fertilization level; At the same irrigation level, the higher the fertilizer application, the greater the NO3--N concentration in groundwater; The effects of irrigation and nitrogen application on groundwater NO3--N concentrations were shown to be as follows：irrigation1）+ conventional fertilization（N2, 370 kg·hm-2 nitrogen fertilizer+2 470 kg·hm-2 organic fertilizer）that rice yield was maximized under this treatment at 8 375 kg·hm-2, with at the same time, the NO3--N concentration under the groundwater was the smallest, which was only（5.06±0.01）mg·L-1 for the whole fertility period.Nitrogen fertilizer applications exceeding 370 kg·hm-2 will exceed crop N uptake, resulting in NO3--N accumulation（3.69 mg·kg-1）in the 0 to 80 cm soil profile, which thus posing a danger of potential leaching of NO3--N.There were no significant differences in soil water content between different irrigation and nitrogen fertilizer treatments. The differences in rice yield were not significant between low and high irrigation treatments（200 mm and 400 mm）, indicating that the sandy ecosystems in this region have the potential to improve water use efficiency by controlling the irrigation amount. |
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