秸秆还田对外源氮在土壤中转化及其微生物响应的影响

发布时间：2018-12-18 07:54

【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28~33μg,~(15)N-NH+4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-NH+4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.
[Abstract]:Straw returning to the field is an important measure to improve soil fertility in agricultural production, and the high C / N ratio in straw makes the utilization ratio of straw carbon low and the greenhouse gas emission higher. Therefore, inorganic nitrogen and phosphorus fertilizer can control the measurement ratio of elements in soil. Increase microbial activity and utilization of elements to promote soil fertility. In this study, under the condition of simulated straw returning to the field, adding ~ (15) N labeled inorganic nitrogen fertilizer was used to study the effects of different nutrient fertilizers on the transformation and distribution of exogenous nitrogen in soil, as well as the characteristics of microbial response. The results showed that the content of ammonium nitrogen and total nitrogen in soil and soil solution was increased by adding straw. Under the combined application of straw and inorganic nitrogen fertilizer, the content of ~ (15) N-TN in soil was maintained at 2833 渭 g / g N-NH _ (4) during the first 30 days of culture, and then decreased gradually during the first 30 days. P increased the contents of ~ (15) N-TN and ~ (15) N-NH _ 4 in soil, but decreased ~ (15) N in soil solution by 28%. The distribution of inorganic nitrogen fertilizer in the soil indicated that the proportion of ~ (15) N in the soil was kept at 52and 61.The addition of phosphorus fertilizer increased the distribution ratio of ~ (15) N in the soil by 16.5%. However, the proportion of ~ (15) N in soil solution decreased from 36% on the fifth day to 30 at 100 days, which reduced the loss of exogenous ~ (15) N by 1.2 times. The addition of straw promoted the microbial activity and significantly increased the amount of soil MBN. The addition of inorganic fertilizer further promoted the activity of soil microorganism. After 100d culture experiment, the addition of straw, inorganic nitrogen and phosphorus fertilizer increased MBN by 2.0 and 2.2 times as compared with the control treatment at the same time. The addition of phosphorus fertilizer promoted the utilization of ~ (15) N by microorganism, and the amount of ~ (15) N-MBN increased by 1.5 times than that of straw and nitrogen fertilizer treatment. The results of the study on the activity of soil nitrogen invertase (尾 -1N-acetyl glucosaminidase, NAG) showed that nitrogen fertilizer decreased soil enzyme activity and substrate affinity, but when nitrogen and phosphorus fertilizer were added at the same time, The enzyme activity increased 48.1% compared with the single straw treatment. This study can provide a theoretical basis for further understanding the nitrogen cycle in paddy soil ecosystem, improving soil fertility and reducing greenhouse gas emissions.
【作者单位】：中南林业科技大学环境科学与工程学院;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;
【基金】：国家自然科学基金项目(31470629,41501321) 湖南省自然科学基金项目(2016JJ3132) 政府间国际科技创新合作重点专项(S2016G0053)
【分类号】：S141.4

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