Purpose

Determine the response of soil respiration and microbial biomass in planted and unplanted soil to drying and rewetting stress.

Methods

Barley was grown at high density in a loamy sand at 75% of water holding capacity to obtain planted soil. For unplanted soil, pots without plants were kept in the same conditions. After 4 weeks, soil from planted (brushed off the roots) and unplanted pots were used for the subsequent incubation experiment. For drying and rewetting (DRW), the soil was dried for 7 days immediately after collection of the soil. On day 8, the soil was rewet quickly to 75% of water holding capacity and kept moist until day 14. For the constantly moist treatment (CM), the soil was kept at 75% of WHC for 2 weeks.

Results

In CM, respiration rates were higher in planted than unplanted soil, but microbial biomass C (MBC) did not differ between planting treatments. In DRW, respiration rates rapidly decreased in the dry period, irrespective of planting treatment. The flush of respiration after rewetting was 50% greater in planted than unplanted soil. Only in planted soil, MBC doubled after rewetting (from day 7 to 9), but then halved again to day 14.

Conclusion

Previous planting increases organic C supply to microbes which increases the respiration flush after rewetting and microbial growth.

中文翻译：

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种植土壤中土壤呼吸和微生物生物量对干燥和再润湿的响应大于未种植土壤

目的

确定种植和未种植土壤中土壤呼吸和微生物生物量对干燥和再润湿胁迫的响应。

方法

大麦在肥沃的沙子中以高密度种植，保水能力为 75%，以获得种植土壤。对于未种植的土壤，没有植物的盆保持在相同的条件下。4周后，种植的（刷掉根部）和未种植的盆的土壤用于随后的孵化实验。对于干燥和再润湿 (DRW)，在收集土壤后立即将土壤干燥 7 天。在第 8 天，土壤快速回湿至持水量的 75%，并保持湿润直到第 14 天。对于持续湿润处理 (CM)，土壤保持在 75% 的 WHC 下 2 周。

结果

在 CM 中，种植土壤的呼吸速率高于未种植土壤，但微生物生物量 C (MBC) 在种植处理之间没有差异。在 DRW 中，无论种植处理如何，干旱期的呼吸率都会迅速下降。重新润湿后的呼吸冲洗在种植的土壤中比未种植的土壤大 50%。仅在种植的土壤中，再润湿后 MBC 翻倍（从第 7 天到第 9 天），但到第 14 天又减半。

结论

先前的种植增加了对微生物的有机碳供应，这增加了再润湿和微生物生长后的呼吸冲洗。