Deep ploughing increases agricultural soil organic matter stocks
Deep ploughing increases agricultural soil organic matter stocks
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DOI：
10.1111/gcb.13289
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发表时间：
2016-08-01
影响因子：
11.6
通讯作者：
Nieder, Rolf
中科院分区：
文献类型：
--
作者：
Alcantara, Viridiana;Don, Axel;Nieder, Rolf
由于土壤有机碳（SOC）含量普遍较低，土壤有机碳（SOC）储量较大，因此在全球碳循环中发挥着重要作用。然而，提高有机碳储量的措施通常集中在表土上。深耕是一种全球通用的土壤结构改良方法，旨在优化作物生长条件，通过深耕来评估耕层土壤中有机碳的长期储存和稳定性。深耕的一个影响是土壤表层形成的有机碳转移到底土中，同时将缺乏有机碳的底土物质混合到新的表土中。深耕的农田代表了地下土壤中富含soc物质的独特的长期原位孵化。在这项研究中，我们对35-50年前耕至55-90cm深度的5种壤土和5种沙土进行了取样。相邻的、类似管理但传统耕作的子地块作为参考取样。深耕土壤的有机碳含量比对照小区平均高42 +/- 13%。深耕45年后，新表层土壤的有机碳含量仍比对照表层土壤低15%，表明表层土壤具有长期的有机碳积累潜力。埋藏沙质土壤的体外培养实验表明，与对照表层土相比，埋藏表层土的潜在有机碳矿化率低63 +/- 6%，单位有机碳矿化率低67 +/- 2%。深埋沙质表层土的碳氮比大于对照表层土，表明深耕保留了土壤有机碳。深埋壤土表层土壤单位有机碳矿化量与对照表层土壤无显著差异。然而，56 +/- 4%的初始有机碳被保留在埋藏的表层土壤中。由此可见，深耕通过扩大富碳物质的储存空间有助于固碳。
Subsoils play an important role within the global C cycle, since they have high soil organic carbon (SOC) storage capacity due to generally low SOC concentrations. However, measures for enhancing SOC storage commonly focus on topsoils. This study assessed the long-term storage and stability of SOC in topsoils buried in arable subsoils by deep ploughing, a globally applied method for breaking up hard pans and improving soil structure to optimize crop growing conditions. One effect of deep ploughing is translocation of SOC formed near the surface into the subsoil, with concomitant mixing of SOC-poor subsoil material into the new' topsoil. Deep-ploughed croplands represent unique long-term insitu incubations of SOC-rich material in subsoils. In this study, we sampled five loamy and five sandy soils that were ploughed to 55-90cm depth 35-50years ago. Adjacent, similarly managed but conventionally ploughed subplots were sampled as reference. The deep-ploughed soils contained on average 42 +/- 13% more SOC than the reference subplots. On average, 45years after deep ploughing, the new' topsoil still contained 15% less SOC than the reference topsoil, indicating long-term SOC accumulation potential in the topsoil. In vitro incubation experiments on the buried sandy soils revealed 63 +/- 6% lower potential SOC mineralisation rates and also 67 +/- 2% lower SOC mineralisation per unit SOC in the buried topsoils than in the reference topsoils. Wider C/N ratio in the buried sandy topsoils than in the reference topsoils indicates that deep ploughing preserved SOC. The SOC mineralisation per unit SOC in the buried loamy topsoils was not significantly different from that in the reference topsoils. However, 56 +/- 4% of the initial SOC was preserved in the buried topsoils. It can be concluded that deep ploughing contributes to SOC sequestration by enlarging the storage space for SOC-rich material.