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| Rice Yield, Nitrogen Use Efficiency(NUE) and Nitrogen Leaching Losses as Affected by Long-term Combined Applications of Manure and Chemical Fertilizers in Yellow River Irrigated Region of Ningxia, China |
| Received:November 18, 2014 |
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| KeyWord:Yellow River Irrigated Region of Ningxia;paddy rice field;manure;nitrogen leaching losses;nitrogen balance |
| Author Name | Affiliation | E-mail | | LIU Ru-liang | Institute of Agricultural Resources and Environment, Ningxia Academy of Agro-forestry Science, Yinchuan 750002, China | | | ZHANG Ai-ping | China Institute of Environment and Sustainable Development in Agriculture, China Academy of Agricultural Science/Key Laboratory of Agriculture Environment and Climate Change, Ministry of Agriculture, Agricultural Clean Watershed Innovation Team, Beijing 100081, China | apzhang0601@126.com | | LI You-hong | Institute of Agricultural Resources and Environment, Ningxia Academy of Agro-forestry Science, Yinchuan 750002, China | | | WANG Fang | Institute of Agricultural Resources and Environment, Ningxia Academy of Agro-forestry Science, Yinchuan 750002, China | | | ZHAO Tian-cheng | Institute of Agricultural Resources and Environment, Ningxia Academy of Agro-forestry Science, Yinchuan 750002, China | | | CHEN Chen | Institute of Agricultural Resources and Environment, Ningxia Academy of Agro-forestry Science, Yinchuan 750002, China | | | HONG Yu | Institute of Agricultural Resources and Environment, Ningxia Academy of Agro-forestry Science, Yinchuan 750002, China | |
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| Abstract: |
| To maximize rice yields, excessively high nitrogen fertilization and irrigation are very common management practices in the Yellow River Irrigated Region of Ningxia. However, these practices have greatly increased the risks of nitrogen losses and non-point source pollution. Production systems with more yields and less environmental impacts are urgently needed in this region. A continuous four year field experiment was conducted to evaluate the effects of combined applications of manure and chemical fertilizers on rice yields and nitrogen utilization and nitrogen leaching losses in Qingtongxia in the Yellow River Irrigated Region of Ningxia. Five nitrogen treatments were used:no nitrogen fertilizer(T1), conventional chemical nitrogen of 300 kg·hm-2(T2), chemical plus organic-chemical nitrogen of 210 kg·hm-2 + manure nitrogen of 90 kg·hm-2(T3), reduced chemical nitrogen of 240 kg·hm-2(T4), and optimized chemical nitrogen of 195 kg·hm-2 + manure nitrogen of 45 kg·hm-2(T5). The experimental design was a randomized complete block with three replicates. Each plot was 45 m2(5 m×9 m). An in-situ leaching device was used to sample leachate from 20 cm, 60 cm, and 100 cm soil depths. Total nitrogen, NO3--N and NH4+-N leaching losses were calculated based on nitrogen concentrations in the leachate and the volume of the leachate. Compared with the conventional chemical nitrogen, rice grain yields in all treatments with lowered chemical nitrogen with and without manure did not decrease, whereas nitrogen use efficiency was 5.2 and 1.9 percentage points higher. The total nitrogen concentration in the surface water and nitrogen leaching losses at different soil depths were all significantly decreased in lowered chemical nitrogen combined with manure as compared to the conventional chemical nitrogen. At 20 cm soil depth, total nitrogen leaching losses were 9.99% and 16% lower than that in the conventional chemical nitrogen, while 17.9% and 9.3% lower at 100 cm soil depth. Under the same nitrogen level, apparent nitrogen losses were respectively reduced by 12.1% and 12.5% in combined manure and chemical fertilizer treatments over the conventional chemical nitrogen and reduced chemical nitrogen alone. In conclusion, applying chemical nitrogen of 195 kg·hm-2 + manure nitrogen of 45 kg·hm-2 could maintain paddy rice yields while alleviating environmental pollution in the Yellow River Irrigated Region of Ningxia. |
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