Geographical variation in carbon dioxide fluxes from soils in agro-ecosystems and its implications for life-cycle assessment
Geographical variation in carbon dioxide fluxes from soils in agro-ecosystems and its implications for life-cycle assessment
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农业生态系统土壤二氧化碳通量的地理变化及其对生命周期评估的影响
DOI：
10.1111/j.1365-2664.2009.01622.x
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发表时间：
2009
影响因子：
5.7
通讯作者：
Davey L. Jones
中科院分区：
文献类型：
--
作者：
G. Koerber;G. Edwards‐Jones;P. Hill;L. M. Canals;P. Nyeko;Elizabeth H. York;Davey L. Jones
1.土壤中二氧化碳(CO2)的交换对农业生态系统的全球变暖潜力(GWP)有很大贡献。由于土壤类型、气候条件和土地管理措施的不同，不同地理位置的二氧化碳交换可能会有显著差异。食品工业正在为其产品开发碳足迹，这就需要将土壤中的二氧化碳交换与食物链上的其他二氧化碳排放相结合。在不同的地理位置种植某些作物可能是有利的，以最大限度地减少土壤的二氧化碳排放，这可能会抵消食物链中的其他排放，如运输。2.计算了英国、西班牙和乌干达种植园艺作物的土壤碳平衡值。生态系统净生产量(NEP)首先由净初级生产量(NPP)和异养土壤呼吸(Rh)之差计算得出。NPP和Rh都是通过密集的直接野外测量来估算的。其次，从净生物群生产量中减去作物生物量，计算出净生物群生产量(NBP)，以表示碳平衡。根据最近关于碳足迹的讨论以及在食品生命周期评估(LCA)的背景下，讨论了土壤交换的重要性。3.作物相对生物量和不同国家普遍存在的相对湿度是影响NEP和NBP大小的主要因素。生菜和豌豆的大部分生物量作为作物从田间移走，因此NEP和NBP主要为负值。在乌干达种植的生菜(-16.5和-17t C ha-1年-1，而英国和西班牙的NEP和NBP分别为4·8到7·4和-5·1到6·3t C ha-1年-1)被放大，那里的气候提高了Rh。4.合成与应用。这项研究论证了土壤排放在蔬菜整个生命周期中的重要性。这种排放的可变性表明，即使在一个国家内，为食品碳足迹分配一个单一的值也可能是不够的。异养土壤呼吸高的地区，如西班牙和乌干达(分别为21.9tCha-1年和21.6tCha-1年)，可以通过种植残留物返还土壤的作物来缓解气候对作物生产碳成本的负面影响。这将最大限度地减少这些农业生态系统的二氧化碳净排放量。
1. Exchange of carbon dioxide (CO2) from soils can contribute significantly to the global warming potential (GWP) of agro-ecosystems. Due to variations in soil type, climatic onditions and land management practices, exchange of CO2 can differ markedly in different geographical locations. The food industry is developing carbon footprints for their products necessitating integration of CO2 exchange from soils with other CO2 emissions along the food chain. It may be advantageous to grow certain crops in different geographical locations to minimize CO2 emissions from the soil, and this may provide potential to offset other emissions in the food chain, such as transport. 2. Values are derived for the C balance of soils growing horticultural crops in the UK, Spain and Uganda. Net ecosystem production (NEP) is firstly calculated from the difference in net primary production (NPP) and heterotrophic soil respiration (Rh). Both NPP and Rh were estimated from intensive direct field measurements. Secondly, net biome production (NBP) is calculated by subtracting the crop biomass from NEP to give an indication of C balance. The importance of soil exchange is discussed in the light of recent discussions on carbon footprints and within the context of food life-cycle assessment (LCA). 3. The amount of crop relative to the biomass and the Rh prevailing in the different countries were the dominant factors influencing the magnitude of NEP and NBP. The majority of the biomass for lettuce Lactuca sativa and vining peas Pisum sativum, was removed from the field as crop; therefore, NEP and NBP were mainly negative. This was amplified for lettuces grown in Uganda (-16·5 and -17 t C ha-1 year-1 compared to UK and Spain -4·8 to 7·4 and -5·1 to 6·3 t C ha-1 year-1 for NEP and NBP, respectively) where the climate elevated Rh. 4. Synthesis and applications. This study demonstrates the importance of soil emissions in the overall life cycle of vegetables. Variability in such emissions suggests that assigning a single value to food carbon footprints may not be adequate, even within a country. Locations with high heterotrophic soil respiration, such as Spain and Uganda (21·9 and 21·6 t C ha-1 year-1, respectively), could mitigate the negative effects of climate on the C costs of crop production by growth of crops with greater returns of residue to the soil. This would minimize net CO2 emissions from these agricultural ecosystems.