Agroscope, Climate and Agriculture Group, Research Division Agroecology and Environment, Reckenholzstrasse 191, CH 8046, Zurich, Switzerland.
Sci Rep. 2020 May 6;10(1):7634. doi: 10.1038/s41598-020-64275-y.
Peatlands accumulate organic matter (OM) under anaerobic conditions. After drainage for forestry or agriculture, microbial respiration and peat oxidation induce OM losses and change the stoichiometry of the remaining organic material. Here, we (i) evaluate whether land use (cropland CL, grassland GL, forest FL, natural peatland NL) is associated with different peat stoichiometry, (ii) study how peat stoichiometry changes with OM content and (iii) infer the fate of nitrogen upon soil degradation. Organic C and soil N were measured for 1310 samples from 48 sites in Switzerland, and H and O for 1165. The soil OM content and C/N ratio were most sensitive to land use and are hence best suited as indicators for peatland degradation. OM contents (CL < GL < FL < NL), H/C, O/C, C/N ratios, and OM oxidation states were significantly different between land use types in top- and subsoils. With decreasing bulk OM content, C was relatively depleted while H and particularly N were higher. The data suggest very high N mobilization rates from strongly decomposed peat in agricultural topsoil. A comparison to peat C and N from mostly intact peatlands of the Northern hemisphere reveals that agriculture and, to a lesser extent, forestry induce a progressed state of soil degradation.
泥炭地在厌氧条件下积累有机物 (OM)。在用于林业或农业排水后，微生物呼吸和泥炭氧化会导致 OM 损失，并改变剩余有机物质的化学计量。在这里，我们 (i) 评估土地利用（耕地 CL、草地 GL、森林 FL、自然泥炭地 NL）是否与不同的泥炭化学计量有关，(ii) 研究泥炭化学计量如何随 OM 含量而变化，(iii) 推断土壤退化时氮的命运。对瑞士 48 个地点的 1310 个样本进行了土壤有机碳和氮的测量，对 1165 个样本进行了 H 和 O 的测量。土壤 OM 含量和 C/N 比对土地利用最敏感，因此最适合作为泥炭地退化的指标。表层和底层土壤中，不同土地利用类型之间的 OM 含量（CL < GL < FL < NL）、H/C、O/C、C/N 比和 OM 氧化态存在显著差异。随着体相 OM 含量的降低，C 相对耗竭，而 H 尤其是 N 含量更高。数据表明，农业表土中强烈分解的泥炭具有很高的氮迁移率。与北半球大部分未受干扰的泥炭地的泥炭 C 和 N 进行比较表明，农业和在较小程度上的林业会导致土壤退化的进展状态。
