Greenhouse gas mitigation potential of the world's grazing lands: Modeling soil carbon and nitrogen fluxes of mitigation practices
Greenhouse gas mitigation potential of the world's grazing lands: Modeling soil carbon and nitrogen fluxes of mitigation practices
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DOI：
10.1016/j.agee.2015.03.029
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发表时间：
2015-09-01
影响因子：
6.6
通讯作者：
Conant, Richard T.
中科院分区：
文献类型：
--
作者：
Henderson, Benjamin B.;Gerber, Pierre J.;Conant, Richard T.
这项研究提供了对世界原生牧场和耕作牧场中选定的一系列管理措施的温室气体净减排潜力的估计。世纪模型和日分模型被用来计算与这些实践相关的土壤碳储量、土壤N2O排放和反刍动物的饲料清除的变化。GLEAM与这些模型结合使用，以确定放牧区边界，并对牧草消费、动物生产和动物温室气体排放之间的联系进行参数化。这项研究提供了一种替代通常的方法，即通过对土壤、牧草和动物之间的联系进行建模，从少量的实地研究中进行推断，它揭示了世界牧场上碳固存做法的净缓解潜力。本研究评估了三种不同的缓解措施，即改进放牧管理、豆类播种和氮肥施肥。我们估计，放牧压力的优化可以封存148Tg CO2 Yr(-1)。203TgCO2年(-1)用于豆科牧草播种的土壤固碳潜力高于改善放牧管理的土壤固碳潜力，尽管其应用面积要小得多。然而，按二氧化碳当量计算，豆类的N2O排放估计抵消了其全球碳固存收益的28%。相反，在所有地区，氮肥的N2O排放量都超过了土壤碳汇。我们估计的增加牧场碳储量的潜力低于早先的全球估计(Smith等人，2007年；Lal，2004年)，主要是因为我们估计缓解措施有效的牧场面积要小得多。一个很大的担忧是，如果在这个相对较小的有效区域之外应用，这种做法的高风险，特别是豆类，会增加基于土壤的温室气体。需要开展更多工作，根据牧场的生物物理和管理特点制定指标，以确定适合牧场的区域，然后才能认为这些做法已准备好大规模实施。与更高的牧草产量相关的额外的反刍动物温室气体排放可能会大大降低这些做法的缓解潜力，但可能有助于提高温室气体效率的畜牧业生产。(C)2015爱思唯尔B.V.保留所有权利。
This study provides estimates of the net GHG mitigation potential of a selected range of management practices in the world's native and cultivated grazing lands. The Century and Daycent models are used to calculate the changes in soil carbon stocks, soil N2O emissions, and forage removals by ruminants associated with these practices. GLEAM is used in combination with these models to establish grazing area boundaries and to parameterize links between forage consumption, animal production and animal GHG emissions. This study provides an alternative to the usual approach of extrapolating from a small number of field studies and by modeling the linkage between soil, forage and animals it sheds new light on the net mitigation potential of C sequestration practices in the world's grazing lands. Three different mitigation practices are assessed in this study, namely, improved grazing management, legume sowing and N fertilization. We estimate that optimization of grazing pressure could sequester 148 Tg CO2 yr(-1). The soil C sequestration potential of 203 Tg CO2 yr(-1) for legume sowing was higher than for improved grazing management, despite being applied over a much smaller total area. However, N2O emissions from legumes were estimated to offset 28% of its global C sequestration benefits, in CO2 equivalent terms. Conversely, N2O emissions from N fertilization exceeded soil C sequestration, in all regions. Our estimated potential for increasing C stocks though in grazing lands is lower than earlier worldwide estimates (Smith et al., 2007; Lal, 2004), mainly due to the much smaller grazing land area over which we estimate mitigation practices to be effective. A big concern is the high risk of the practices, particularly legumes, increasing soil-based GHGs if applied outside of this relatively small effective area. More work is needed to develop indicators, based on biophysical and management characteristics of grazing lands, to identify amenable areas before these practices can be considered ready for large scale implementation. The additional ruminant GHG emissions associated with higher forage output are likely to substantially reduce the mitigation potential of these practices, but could contribute to more GHG-efficient livestock production. (C) 2015 Elsevier B.V. All rights reserved.