| 秸秆还田对外源氮在土壤中转化及其微生物响应的影响 |
| 摘要点击 2122 全文点击 1135 投稿时间：2016-09-27 修订日期：2016-11-15 |
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| 中文关键词 氮素 微生物 转化 15 N示踪 酶活性 |
| 英文关键词 nitrogen microbe transformations 15N tracing enzyme activity |
| 作者 | 单位 | E-mail | | 陈珊 | 中南林业科技大学环境科学与工程学院, 长沙 410004
中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 | gtd@isa.ac.cn | | 丁咸庆 | 中南林业科技大学环境科学与工程学院, 长沙 410004
中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 | | | 祝贞科 | 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 | | | 王娟 | 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 | | | 彭佩钦 | 中南林业科技大学环境科学与工程学院, 长沙 410004 | pqpeng123@sina.com | | 葛体达 | 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 | | | 吴金水 | 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 | |
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| 中文摘要 |
| 秸秆还田是农业生产上提高土壤肥力的重要措施，而秸秆中较高的碳氮比，使秸秆碳的利用率较低，温室气体排放较高，因此配施无机氮磷肥能够调控土壤中元素计量比，增加微生物活性和元素利用率，促进土壤肥力提升.本研究选择在模拟秸秆还田条件下，添加15 N标记的无机氮肥，研究不同养分肥料添加对土壤中外源氮转化与分配的影响，以及微生物响应特征.结果表明，秸秆添加增加了土壤和土壤溶液中铵态氮和总氮含量；秸秆与无机氮肥配施条件下，土壤中15 N-TN在100 d培养时期内基本保持在28~33 μg，15 N-NH4+在前30 d培养时期内逐渐增加，而后逐渐降低；施P增加了土壤中15 N-TN和15 N-NH4+的含量，却使土壤溶液中15 N量降低了28%.无机氮肥在土壤中的分配表明，15 N在土壤中的比例基本保持在52%~61%，磷肥的添加使15 N在土壤中的分配比例最大提高了16.5%，而土壤溶液中15 N的比例由第5 d的36%降低至100 d时30%，使外源15 N损失量减少了1.2倍.秸秆添加促进了微生物活性，显著提高了土壤MBN的量；而无机肥料的添加进一步促进了土壤微生物的活性，100 d培养实验后，秸秆与无机氮、磷肥同时添加使MBN增加到对照处理的2.0和2.2倍.磷肥添加促进了微生物对15 N的利用，使15 N-微生物生物量氮（15 N-MBN）的量比添加秸秆和氮肥处理的提高了1.5倍.对土壤氮转化酶活性（β-1，4-N-乙酰葡糖氨糖苷酶，NAG）的研究结果表明，氮肥降低了土壤酶活性和底物亲和性，而氮磷肥同时添加时，酶活性较单加秸秆处理提高了48.1%.本研究可为深入了解稻田土壤生态系统氮循环、实现农田土壤肥力提升和温室气体减排提供理论依据. |
| 英文摘要 |
| Returning straw to the field provides an important source of fertilizer that can increase soil fertility. However, the rate of straw carbon utilization is low and large amounts of greenhouse gases are emitted due to the high carbon to nitrogen ratio of the straw mass. In this regard, the application of inorganic nitrogen and phosphate fertilizers can control the ratio of elements in the soil, increase the activity of microorganisms and their utilization of elements, and promote the improvement of soil fertility. In this study, straw application conditions were simulated, and inorganic nitrogen fertilizer labeled with 15N was added to examine the effects of different nutrient fertilizer additions on the transformation and distribution of exogenous nitrogen in the soil, and also the characteristics of the microbial response. The results showed that application of straw increased the contents of ammonia nitrogen and total nitrogen in the soil and soil solution. When both straw and inorganic nitrogen fertilizer were applied, the 15N-TN in the soil remained at 28 to 33 μg during the 100-day culture phase. In contrast, 15N-NH4+ increased gradually during the initial 30 days of the culture phase, but subsequently decreased gradually. Application of phosphate increased the contents of 15N-TN and 15N-NH4+ in the soil, but decreased the content of 15N in the soil solution by 28%. The distribution of inorganic nitrogen in the soil showed that the proportion of 15N in the soil remained at 52%-61%. Addition of phosphate fertilizer increased the distribution ratio of 15N in the soil by up to 16.5%, whereas the proportion of 15N in the soil solution decreased from 36% on the fifth day to 30% on the 100th day, thereby the loss amount of 15N reduced by 1.2-fold. Addition of straw promoted microbial activity and significantly increased the microbial biomass nitrogen (MBN) content of the soil. Addition of inorganic fertilizer further promoted the microbial activity of the soil. After the 100-day culture experiment, the addition of straw, inorganic nitrogen, and phosphate fertilizer increased MBN to between 2.0-fold and 2.2-fold that of the control treatments. Addition of phosphate fertilizer increased the utilization of 15N by microorganisms, so that the amount of 15N-MBN was 1.5-fold higher than that of treatments where only straw and nitrogen fertilizer were added. Examination of soil enzyme activity showed that nitrogen fertilizer reduced soil enzyme activity and substrate affinity. When both nitrogen and phosphate fertilizers were added, the enzyme activity was 48.1% higher than that when only straw was added. The findings of this study thus provide a theoretical basis for furthering our understanding on the nitrogen cycle of the paddy soil ecosystem, the improvement of soil fertility, and the reduction of greenhouse gas emissions. |
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