| 摘要: |
| 【目的】探究3种主要水旱轮作系统下，优化施肥对当季稻田NH3挥发及氮素利用率的影响。【方法】试验设置水稻-小麦、水稻-蔬菜与水稻-冬闲田3种水旱轮作系统，每种轮作系统下设农民习惯施肥方式（FFP）和优化施肥方式（OPT）2种施肥处理，以不施肥处理为对照（CK），其中农民习惯施肥方式氮肥以基肥与分蘖肥施用量比例5∶5施入，优化施肥方式氮肥以基肥、分蘖肥、穗肥施用量比例5∶3∶2施入。于2015─2016年，采用传统抽气密闭室法，田间原位监测了不同处理以及4个环境因子（田面水NH+4-N质量浓度、水层pH、温度和深度）对当季稻田NH3挥发的影响，并分析了4个环境因子与NH3挥发通量的相关性，最后测定了不同处理水稻的产量、氮农学利用率、氮回收效率以及氮偏生产力。【结果】当氮肥作为基肥和分蘖肥施用后，由于尿素在水中的快速分解，各处理NH3挥发通量均在施肥后第2天达到峰值，随后急剧下降，至第10天左右趋近于零；优化施肥方式下，穗肥施用后，由于施肥量较少且此时水稻对氮素的吸收利用增加，NH3挥发通量无明显峰值，趋近于零。NH3挥发积累量受施肥方式影响显著（P<0.05），轮作制度及其与施肥方式交互作用对NH3挥发通量影响不显著。3种轮作制度下，农民习惯施肥方式NH3挥发积累量占氮肥施用量比例为25.9%~27.6%，显著高于优化施肥方式（22.6%~23.0%）。3种轮作制度下，NH3挥发通量均主要受田面水NH+4-N质量浓度的影响，且二者间呈显著正相关关系，与水层pH、温度均无显著相关性；NH3挥发通量与水层深度呈负相关关系，其中只有部分处理相关性达显著水平。在3种水旱轮作系统下，优化施肥方式平均水稻产量（9.0~10.2 t/hm2）与农民习惯施肥方式（8.9~10.2 t/hm2）差异均不显著，但氮肥农学利用率（21.3~26.1 kg/kg）、氮回收效率（55.6%~60.3%）、氮偏生产力（50.0~56.8 kg/kg）与农民习惯施肥方式（氮肥农学利用率12.6~15.6 kg/kg，氮回收效率35.0%~37.6%，氮偏生产力29.8~34.1 kg/kg）相比均有显著提高。【结论】不同施肥方式是影响NH3挥发的主要因素，在不同的水旱轮作系统下优化施肥均可以通过氮肥运筹，在减少施肥量和保证产量水平的基础上，降低稻田的NH3挥发损失，提高氮素利用率。 |
| 关键词: 水旱轮作 优化施肥 氨挥发 氮肥利用率 |
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| 基金项目:国家“973”计划项目“肥料养分持续高效利用机理与途径”（2013CB127403）；国家公益性行业科研专项“水田两熟区耕地培肥与合理农作制”（201503122） |
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| Effect of optimized fertilization on ammonia volatilization of paddy rice under different rotation systems |
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SHENG Weihong,LIU Wenbo,ZHAO Chenguang,et al
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| Abstract: |
| 【Objective】This study investigated the effect of optimal fertilization on NH3 volatilization and nitrogen use efficiency in rice fields in three paddy rice upland crop rotation systems.【Method】The farmer’s fertilizer practice (FFP),optimal fertilization (OPT) and control (CK) were established in three cropping systems including rice-wheat (RW),rice-vegetable (RV) and rice-fallow (RF) cropping systems.The application ratio of basal and tiller was 5∶5 under FFP and the application ratio of basal,tiller and panicle was 5∶3∶2 under OPT.Through in-situ monitoring,the effects of different treatments and environmental factors (NH+4-N concentration,water layer pH,water layer temperature and water depth) on NH3 volatilization were studied using a continuous airflow enclosure method under different crop rotation systems from 2015 to 2016.The correlation between four environmental factors and NH3 volatiles was also analyzed.Finally,the rice yield,nitrogen utilization efficiency,nitrogen recovery efficiency and nitrogen partial productivity were evaluated.【Result】Due to the rapid decomposition of urea in water,NH3 emission fluxes peaked on the second day after nitrogen fertilizer was used as basal and tillering fertilizer in the paddy field,and then decreased sharply to zero in the tenth day.After the application of panicle fertilizer,because of the less fertilizer and increased nitrogen utilization,the NH3 emission flux of OPT was close to zero.The total NH3 volatilization amount was significantly affected by fertilization method (P<0.05),and insignificantly affected by rotation and its interaction with fertilization.The ratio of NH3 volatilization to total N application under FFP was 25.9%-27.6%,which was significantly higher than that under OPT (22.6%-23.0%).Significant positive correlation was observed between NH3 flux and NH+4-N concentration in surface water under all three rotations.The temperature of water layer and pH had no significant effects on NH3 flux.Negative correlation was observed between NH3 flux and water depth,with significant correlation in partial treatments.There was no significant difference in rice yield between FFP (8.9-10.2 t/hm2) and OPT (9.0-10.2 t/hm2),while the nitrogen agronomy efficiency (21.3-26.1 kg/kg),nitrogen recovery efficiency (55.6%-60.3%) and nitrogen partial factor productively (50.0-56.8 kg/kg) under OPT were higher than those under FFP (12.6-15.6 kg/kg,35.0%-37.6% and 29.8-34.1 kg/kg).【Conclusion】Fertilization method was the main factor influencing NH3 volatilization.OPT reduced NH3 volatilization loss and increased nitrogen agronomy efficiency on the basis of reducing fertilizer and ensuring yield. |
| Key words: paddy upland crop rotation system optimal fertilization regime ammonia volatilization nitrogen utilization rate |
