Sucrose application, soil microbial respiration and evolved carbon dioxide isotope enrichment under contrasting land uses
Sucrose application, soil microbial respiration and evolved carbon dioxide isotope enrichment under contrasting land uses
复制标题
DOI：
10.1007/s11104-004-0277-5
复制
发表时间：
2005-01-01
期刊：
影响因子：
4.9
通讯作者：
Hunt, JE
中科院分区：
文献类型：
--
作者：
Kelliher, FM;Barbour, MM;Hunt, JE
有机质的异养分解决定了底物供应速率，包括能量和养分，会限制土壤微生物的活动。在新西兰，土壤天然缺乏氮和磷。化肥应用是田园农业的一部分，田园农业是该国最广泛的土地利用方式。我们推测，放牧草地和原始森林下的有机土壤将处于底物质量和供应速度的极端，因此潜在的微生物对食物机会的反应。通过室内试验测定了土壤微生物对添加新鲜能量(蔗糖)的响应，这些样品包括无根样品和包括根在内的完整岩心。通过呼吸和呼吸碳(C)同位素(增量C-13)浓缩测量来量化反应。超微量蔗糖剂量(0.002.0 5moL kg-1土壤)使森林土壤微生物呼吸速率在2 h内增加近一倍，20h达到峰值，超过0.0 5moL kg-1(土壤)时达到饱和.来自森林的完整土壤核心具有相似的呼吸速率和响应。对于来自放牧牧场的无根土壤样品，呼吸对蔗糖的反应几乎是立即的，依赖于剂量，呼吸速率最高可增加9倍。来自牧场的完整岩芯的呼吸频率要高得多，但对蔗糖的反应相似。在两种土壤中，蔗糖对呼吸作用的影响以及对呼吸碳的相对增量C-13的富集量具有显著的相似性。
Heterotrophic decomposition of organic matter dictates that substrate supply rate, including energy and nutrients, can limit soil microbial activity. In New Zealand, soils are naturally deficient in nitrogen and phosphorus. Fertiliser application is a part of pastoral agriculture, the country's most widespread land use. We postulated that organic soils under grazed pasture and pristine forest would be at the extremes of substrate quality and supply rate, and thus potential microbial response to food opportunities. Soil microbial responses to the addition of fresh energy ( sucrose) were determined by laboratory experiments with root-free samples and intact cores including roots. Responses were quantified by respiration and respired carbon (C) isotope (delta C-13) enrichment measurements. A supra-trace sucrose dose (0.002 mol kg(-1) ( soil)) caused the forest soil's microbial respiration rate to nearly double within 2 h. The peak response took 20 h, and saturation occurred beyond a sucrose dose of 0.05 mol kg(-1) ( soil). Intact soil cores from the forest had similar respiration rates and responses. For root-free soil samples from the grazed pasture, respiration response to sucrose was nearly immediate, dose dependent, and there was up to a 9-fold increase in the rate. Intact cores from the pasture had much higher respiration rates, but a similar response to sucrose. For both soils, the similarity of sucrose application effects on respiration and relative delta C-13 enrichment of the respired carbon was striking.