P and K additions enhance canopy N retention and accelerate the associated leaching
P and K additions enhance canopy N retention and accelerate the associated leaching
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DOI：
10.1007/s10533-019-00543-y
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发表时间：
2019-01
期刊：
影响因子：
4
通讯作者：
M. Chiwa;L. Sheppard;I. Leith;S. Leeson;Y. Sim Tang;J. Cape
中科院分区：
文献类型：
--
作者：
M. Chiwa;L. Sheppard;I. Leith;S. Leeson;Y. Sim Tang;J. Cape
本研究评估了在苏格兰南部 Whim 沼泽的长期氮控制地点，磷 (P) 和钾 (K) 的组合添加对冠层氮 (N) 保留 (CNR) 和随后的冠层浸出的交互影响。环境沉积量为 8 kg N ha−1year−1，另外 11 年中还施用了 8、24 和 56 kg N ha−1year−1 的铵 (NH4+) 或硝酸盐 (NO3−)（含或不含磷和钾）。评估了Calluna vulgaris 下方的贯穿落氮沉积以及叶面N 和P 浓度。结果显示，低剂量NO3-的60%和高剂量NO3-的53%，相比之下，低剂量NH4+的80%和高剂量NH4+的38%被Callunacanopy保留在Callun上。添加磷和钾可增强 CNR，其中高剂量时保留 84% 的 NO3− 和 83% 的 NH4+。 NO3 的 CNR - 增加了溶解有机氮 (DON) 和相关有机阴离子的冠层浸出。 NH4+ 保留通过离子交换增加了树冠镁和钙的浸出。即使在没有磷和钾的情况下进行 11 年的氮暴露，Callunaat Whim 沼泽的叶子 N:P 比率也没有增加，这表明氮暴露不会导致 Callunaat Whim 沼泽的氮饱和。我们的研究得出结论，磷和钾有效性的增加会增强卡卢纳的 CNR，但会加速相关的冠层 DON 和碱阳离子的淋滤，具体取决于叶面的氮状态。
This study evaluated the interactive effects of combined phosphorus (P) and potassium (K) additions on canopy nitrogen (N) retention (CNR) and subsequent canopy leaching at a long-term N manipulation site on Whim bog in south Scotland. Ambient deposition is 8 kg N ha−1year−1and an additional 8, 24, and 56 kg N ha−1year−1of either ammonium (NH4+) or nitrate (NO3−) with or without P and K has been applied over 11 years. Throughfall N deposition belowCalluna vulgarisand foliar N and P concentrations were assessed. Results showed that 60% for low dose and 53% for high dose of NO3−contrasting with 80% for low dose and 38% for high dose of NH4+ontoCallunawas retained byCallunacanopy. The CNR was enhanced by P and K addition in which 84% of NO3−and 83% of NH4+for high dose were retained. CNR for NO3−increased the canopy leaching of dissolved organic N (DON) and associated organic anions. NH4+retention increased canopy leaching of magnesium and calcium through ion exchange. Even over 11-years N exposure without P and K, foliage N:P ratio ofCallunadid not increase, suggesting that N exposure did not lead to N saturation ofCallunaat Whim bog. Our study concluded that increases in P and K availability enhance CNR ofCallunabut accelerate the associated canopy leaching of DON and base cations, depending on foliar N status.