Mineral nitrogen dynamics in the casts of epigeic earthworms (Metaphire hilgendorfi: Megascolecidae)
Mineral nitrogen dynamics in the casts of epigeic earthworms (Metaphire hilgendorfi: Megascolecidae)
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DOI：
10.1080/00380768.2011.579879
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发表时间：
2011-06
影响因子：
2
通讯作者：
T. Kawaguchi;Tatsuya Kyoshima;N. Kaneko
中科院分区：
文献类型：
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作者：
T. Kawaguchi;Tatsuya Kyoshima;N. Kaneko
定量评价土壤生物活性和生物稳定性的时间动态是理解土壤生态系统养分循环重要性的必要条件。为了解决土壤团聚体和矿质氮（N）的活性如何影响，在实验室条件下，监测了56天的铸造生产率和铸件中的N矿化速率的希氏绿球藻。铸型率为0.79 g干重（DW）g−1 ×鲜重（FW）d −1，92%的铸型在排泄后24 h内是水稳定的。排泄后3天内的粪样中含有333.8 mg铵态氮（-N）kg−1和11.1 mg硝态氮（-N）kg−1，分别是土壤的69.8倍和0.95倍。M.希尔根道菲通过施法活动每天排泄270 µg N g−1 <$FW。土壤呼吸是活跃的，在头两个星期，而溶解有机碳在铸件老化过程中没有变化。随着pH值从6.5降低到5，投加态氮迅速硝化.硝化作用在第28天停止，此时一半的-N被硝化。轻压铸件并没有显着影响呼吸，也没有氮矿化。因此，微生物既不接触碳也不接触氮是硝化停止的原因，但pH值似乎有贡献。在铸件时效过程中，观察到矿物氮的动态变化。
Quantitative evaluation of earthworm activity and temporal dynamics of cast stability are necessary to understand the importance of nutrient cycling in soil ecosystem. To address how earthworm activity influences soil aggregation and mineral nitrogen (N), cast production rate of Metaphire hilgendorfi and N mineralization rate in the casts were monitored for 56 days under laboratory conditions. The casting rate was 0.79 g dry weight (DW) g−1 earthworm fresh weight (FW) day−1 and 92% of the casts were water-stable within 24 h of excretion. The casts within three days of excretion contained 333.8 mg ammonium-nitrogen ( -N) kg−1 and 11.1 mg nitrate-nitrogen ( -N) kg−1, which were 69.8 and 0.95 times higher than those of the soil, respectively. M. hilgendorfi excreted 270 µg N g−1 earthworm FW day−1 through their casting activity. Soil respiration was active in the first two weeks, whereas dissolved organic carbon in casts did not change during aging. Cast -N was nitrified rapidly with subsequent decrease in pH value from 6.5 to 5. Nitrification stopped at 28 days when half of the -N was nitrified. Gentle crushing of casts did not significantly influence respiration nor N mineralization. Therefore microbial access to neither carbon nor N was responsible for the nitrification cessation, but pH appeared to contribute. Dynamic changes in mineral N was observed during cast aging.