Leaf litter C and N cycling from a deciduous permanent crop
Leaf litter C and N cycling from a deciduous permanent crop
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落叶永久作物的落叶碳和氮循环
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
D. Smart
中科院分区：
文献类型：
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作者：
S. Khalsa;C. Almanza;P. Brown;D. Smart
摘要我们对落叶性多年生作物凋落叶碳氮循环及其对氮素管理的影响的认识是有限的。在为期30天的室内培养中，我们比较了15 N天然丰度下对照土壤和对照土壤之间的土壤呼吸以及矿物N [铵态氮（NH 4 +-N）+硝酸盐（NO3--N）]、微生物生物量氮（MBN）、总有机碳（TOC）和总不可提取有机氮（TON）的变化（δ 15 N = 1.08‰）和相同土壤条件下，扁桃（Prunus dulcis（Mill.）D. A. Webb）凋落叶中15 N含量也较高（δ 15 N = 213‰）。此外，一个两端成员的同位素混合模型被用来确定在矿物N，MBN和TON池的N的来源，无论是土壤或落叶。30 d后，对照组和处理组TOC库均下降，而TON库在处理组增加，对照组下降。与对照相比，在3 - 15 d，观察到处理的土壤呼吸增加，矿质氮显著降低（p < 0.05），10 - 30 d的MBN显著增加。30 d后，土壤来源的矿质氮显着大于处理相比，对照。来自凋落叶的矿物氮和MBN组合库遵循正线性趋势（R2 = 0.75），速率为1.39 μg N g−1土壤天−1。这些结果表明，早期分解的凋落叶导致N固定化，然后在后期分解阶段更大的N矿化。直接观察落叶碳和氮循环有助于量化土壤氮保持和果园氮预算的可用性。
ABSTRACT Our understanding of leaf litter carbon (C) and nitrogen (N) cycling and its effects on N management of deciduous permanent crops is limited. In a 30-day laboratory incubation, we compared soil respiration and changes in mineral N [ammonium (NH4+-N) + nitrate (NO3–-N)], microbial biomass nitrogen (MBN), total organic carbon (TOC) and total non-extractable organic nitrogen (TON) between a control soil at 15N natural abundance (δ15N = 1.08‰) without leaf litter and a treatment with the same soil, but with almond (Prunus dulcis (Mill.) D.A. Webb) leaf litter that was also enriched in 15N (δ15N = 213‰). Furthermore, a two-end member isotope mixing model was used to identify the source of N in mineral N, MBN and TON pools as either soil or leaf litter. Over 30 d, control and treatment TOC pools decreased while the TON pool increased for the treatment and decreased for the control. Greater soil respiration and significantly lower (p < 0.05) mineral N from 3 to 15 d and significantly greater MBN from 10 to 30 d were observed for the treatment compared to the control. After 30 d, soil-sourced mineral N was significantly greater for the treatment compared to the control. Combined mineral N and MBN pools derived from leaf litter followed a positive linear trend (R2 = 0.75) at a rate of 1.39 μg N g−1 soil day−1. These results suggest early-stage decomposition of leaf litter leads to N immobilization followed by greater N mineralization during later stages of decomposition. Direct observations of leaf litter C and N cycling assists with quantifying soil N retention and availability in orchard N budgets.