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| Responses of Rice Yield, Rhizospheric Soil Mineral N and N Runoff Loss to Fertilizer N in the Tai Lake Region |
| Received:May 22, 2015 |
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| KeyWord:SPAD;soil mineral N;soil solution;rice yield;N runoff loss |
| Author Name | Affiliation | E-mail | | QIAO Jun | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | TANG Fang | Ministry of Land and Resources of Jintan, Jintan 213200, China | | | ZHU Li-jun | Ministry of Land and Resources of Jintan, Jintan 213200, China | | | YAN Ting-mei | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | tmyan@issas.ac.cn | | ZHAO Dong | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | WANG Ru-hai | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | YANG Lin-zhang | Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China | |
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| Abstract: |
| In this study, mineral N in rhizospheric soil and its solution, SPAD, plant N accumulation, grain yield and N runoff loss were determined under rice grown in six fertilizer N treatments. Results showed that basal N fertilizer significantly increased rhizospheric soil mineral N, but two top dressings had little impacts on mineral N in both soil and soil solution. The SPAD responded well to N fertilizer, but no significant difference in SPAD was found among N treatments. A positive linear relationship existed between N accumulation and fertilizer N rate after tillering stages. Increasing N rates significantly increased nitrogen accumulation in straw at the harvest, but had little impacts on grain N. Rice yield did not always increase with increasing N fertilizer. No significant differences in grain yields were found among N treatments. However, elevated N fertilizer increased total N losses through runoff and decreased the agronomical efficiency of fertilizer N. Considering rice yield, agronomical efficiency and N runoff loss, the recommended maximum N rate should be 243 kg·hm-2. At 135 kg N·hm-2, a comparable yield, the highest agronomical efficiency and the lowest N runoff loss could be obtained. Thus, it is feasible to lower N inputs to avoid high N losses from the paddy field in extremely N polluted area. |
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