Soil carbon stocks in conservation agriculture systems of Southern Africa
Soil carbon stocks in conservation agriculture systems of Southern Africa
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DOI：
10.1016/j.still.2015.09.018
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发表时间：
2016-03-01
影响因子：
6.5
通讯作者：
Frossard, Emmanuel
中科院分区：
文献类型：
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作者：
Cheesman, Stephanie;Thierfelder, Christian;Frossard, Emmanuel
鉴于土壤碳(C)的重要性，以及关于保护性农业可能如何影响其在南部非洲积累的稀缺数据，本研究提供了马拉维、莫桑比克、赞比亚和津巴布韦23个地点的125个农场验证试验的数据。这些验证试验是对2004至2009年间建立的传统农业实践和保护性农业的配对小区比较。整个研究地区的传统种植制度各不相同，尽管它们都是以耕作为基础的，玉米是种植的主要作物。验证试验中提出的处理方法反映了传统做法中的这种可变性，并提出了一种适应的保护性农业选择。因此，这些部位被分成四个具体的治疗比较。测定了4个土层(0~10 cm、10~20 cm、20~30 cm和30~60 cm)的土壤容重和土壤碳浓度，并计算了土壤碳储量。在秸秆生物量收获的基础上，对C投入量进行了评估。在容重和土壤碳浓度方面没有发现一致的差异。只有当模板式耕作玉米-豆类轮作与直播玉米-豆类轮作(有残留物)进行比较时，才发现保护性农业对碳储量有积极影响。即使在保护性农业下增加幅度明显较大，其数量级也很小(类似于2毫克ha(-1))。有限的C输入，在0.1~1g C kg(-1)土壤Yr(-1)之间，可能是C增加的主要瓶颈。这些基于农场验证试验的结果表明，在所研究的系统中，经过长达7年的保护性农业实践后，保护性农业显著增加土壤碳储量的潜力有限。(C)2015爱思唯尔B.V.保留所有权利。
In view of the importance of soil carbon (C) and the scarce data on how conservation agriculture might influence its accumulation in Southern Africa this study presents data from 125 on-farm validation trials across 23 sites in Malawi, Mozambique, Zambia and Zimbabwe. These validation trials are paired plot comparisons of conventional agricultural practice and conservation agriculture that had been established between 2004 and 2009. Traditional cropping systems vary across the study area although they all are tillage based and maize is the main crop grown. The treatments proposed on the validations trials reflect this variability in conventional practice and propose an adapted conservation agriculture option. The sites are thus grouped into four specific treatment comparisons. Bulk density and soil C concentrations were measured from samples collected at four depth layers (0-10 cm, 10-20 cm, 20-30 cm and 30-60 cm), thereafter C stocks were calculated. On the basis of the stover biomass harvest C inputs were assessed. No consistent differences in bulk density and soil C concentrations were found. Carbon stocks were found to be positively influenced by conservation agriculture only when a mouldboard ploughed maize-legume rotation was compared to a direct seeded maize legume rotation (with residue retention). Even when increases were significantly greater under conservation agriculture the order of magnitude was small (similar to 2 Mg ha(-1)). Limited C inputs, ranging between 0.1 and 1 g C kg(-1) soil yr(-1), are likely to be the major bottleneck for C increase. These results, based on on-farm validation trials indicate that there is a limited potential for conservation agriculture to significantly increase soil C stocks after up to 7 years of conservation agriculture practices, in the studied systems. (c) 2015 Elsevier B.V. All rights reserved.