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首页> 外文期刊>Geoderma: An International Journal of Soil Science >Soil respiration and microbial biomass in multiple drying and rewetting cycles - Effect of glucose addition
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Soil respiration and microbial biomass in multiple drying and rewetting cycles - Effect of glucose addition

机译：多种干燥和重新灌水循环中的土壤呼吸与微生物生物量 - 葡萄糖添加的影响

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Previous studies showed that the respiration flush upon rapid rewetting of dry soil decreases with increasing number of drying and rewetting (DRW) cycles which is thought to be due to various factors, for example, lower substrate availability or microbial biomass or changes in microbial community structure. To investigate if the reduction of respiration flush with increasing cycle number is due to lack of available substrate upon rewetting, incubation experiments with four DRW cycles were conducted where glucose solutions of different concentrations, low (50 mu g C g(-1) soil), medium (250 mu g C g(-1) soil) and high (500 mu g C g(-1) soil) were added either in all four cycles or only in cycle 1, 2, 3 or 4 (the other cycles rewetted with water). Additional treatments included a constantly moist control (CM, 70% of maximum water-holding capacity) and DRW treatments with only RO water. When dry soil was rewetted only with RO water, the respiration flush upon rewetting was about twice as high in the first two cycles than in cycles 3 and 4. Soil microbial biomass C (MBC) one day after rewetting remained stable until cycle 3 after which it decreased by about 20%. In all glucose treatments, the glucose induced increase in respiration rate was greater in earlier than later cycles, irrespective of whether glucose was added to one cycle only or in all cycles. But when expressed relative to CM, the respiration rate was greater in the last two cycles. Single glucose addition increased MBC only in the cycle in which it was added whereas repeated glucose addition increased MBC over time. Glucose addition and DRW increased the metabolic quotient, thus reduced C use efficiency. In treatments with glucose added in all four cycles, the metabolic quotient increased with DRW cycle number which indicates lower efficiency in later cycles. It is concluded that lower substrate availability can be one of the reasons for the decrease in respiration flush upon rewetting with cycle number.
机译：以前的研究表明，在越来越多的干燥和重污染（DRW）循环中，呼吸冲洗在干燥的土壤快速重复下降（DRW）循环，这被认为是由于各种因素，例如较低的基材可用性或微生物生物量或微生物群落结构的变化。为了研究随着循环数的增加，呼吸齐平的减少是由于在重新灌注时缺乏可用的基材，进行了具有四个DRW循环的培养实验，其中不同浓度的葡萄糖溶液，低（50μgc（-1）土壤） ，在所有四个循环中或仅在循环1,2,3或4（其他循环中）添加培养基（250μmg（-1）土壤）和高（500μgcg（-1）土壤）（500μgcc（-1）土壤）用水重新撕裂）。额外的治疗包括不断潮湿的控制（CM，最大水控能力的70％）和仅具有RO水的DRW治疗方法。当干燥的土壤只用RO水再次重新润湿时，在重新灌注时呼吸冲洗约为前两个循环的两倍，而不是在循环3和4中的循环3和4.在重新润湿后的一天，土壤微生物生物量C（MBC）保持稳定直至循环3之后它减少了约20％。在所有葡萄糖处理中，葡萄糖诱导的呼吸速率在早期的循环早期更大，而不管是否将葡萄糖加入到一个循环中，或者在所有循环中。但是当相对于Cm表示时，在最后两个周期中呼吸率更大。单葡萄糖添加仅在添加其加入的循环中增加MBC，而重复的葡萄糖添加随时间的增加。葡萄糖添加和DRW增加了代谢商，从而减少了C使用效率。在所有四个循环中加入葡萄糖的处理中，代谢商增加了DRW循环数，表示在以后的循环中较低的效率。得出结论，较低的基板可用性可以是用循环数重新润湿时呼吸呼吸减少的原因之一。

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