Greenhouse gas mitigation potential in smallholder agroecosystem of southern Ethiopia

Abstract

In developing countries, it is critical that novel and swift strategies are devised to help direct and prioritize potential greenhouse gas (GHG) mitigation activities. The Carbon Benefit Project (CBP) analysis tool is a modular, web-based system that allows a consistent comparison of various projects by providing a standardized GHG benefits protocol. In this study, we used the CBP tool to estimate the GHG mitigation potential of the agriculture, forestry, and other land uses (AFOLU) sector and prioritize components for their GHG benefits in three districts of Wolaita Zone, southern Ethiopia. The study area is 90,731 ha of which about 2% was covered by forest, 7% by grassland, 78% by annual crops, 12% by home garden and 1% by settlements. The livestock population in the study area was 512,622 heads. Using the CBP's Detailed Assessment, we estimated mitigation potential in the AFOLU consisting of different managements strategies for a period between 2016 and 2030 in the smallholder agricultural landscape. The results showed an overall GHG benefit of 1,725,052 (±5%) Mg CO₂e from the projected scenario in the study area. The GHG benefit was in the order of biomass C (683,757 Mg CO₂e) > soil C (619,210 Mg CO₂e) > livestock (408,981 Mg CO₂e) illustrating the greater mitigation potential of trees in different systems. The soil C plus biomass C was high in agroforestry systems, and this component had the highest priority for GHG mitigation. This was followed by high enteric methane emission reduction in the livestock category. The GHG emission from manure increased by 71,633 Mg CO₂e in the project because manure was not managed. The surprisingly low GHG benefit of the forest was primarily because of its low land cover (i.e., about 2%) in the agroecosystem. Despite the low GHG benefit in the cropland from best management practices, the improved soil quality in it can affect GHG benefits from other land uses by contributing to their conservation through food security. Thus, a comprehensive project may be a viable strategy in a mitigation effort at the agroecosystem level because of the interactions amongst the components. The CBP analysis tool is useful in prioritizing mitigation activities and may be an option to quantify GHG benefits if studies collate Teir 2 factors in data scarce areas.

Keywords: Agroforestry; Biomass carbon; Carbon benefit project analysis tool; GHG benefit; Livestock; Soil carbon.