Climate-smart agricultural practices in Ethiopia: implications of mitigation of greenhouse gas emissions a review paper

This paper aimed to assess climate smart agricultural practices in Ethiopia, discuss the contribution of climate smart agricultural practices for mitigation of greenhouse gas emissions, and examine determinant factors of climate smart agricultural practices in mitigation of greenhouse gas emissions. Conservation agriculture, integrated soil fertility management, agroforestry, crop diversification, and improved livestock feed and feeding practices are among the best climate smart agricultural practices in Ethiopia. Combination of the adoption of climate smart agricultural practices such as no tillage, increased crop diversity and retaining crop residue on farm have a mitigation potential of increased SOC in non-flooded crops that change in significant ton of CO2e ha year. In addition, a mitigation potential of CH4 in reduced irrigation of paddy rice farms was also changed in ton CO2e ha year. It was found that productivity enhancing interventions in the tropics could reduce emission intensity in dairy systems by up to 0.9 t CO2e per milk. Agroforestry practices and addition of organic fertilizers on the farm increased mitigation potential of 784093 t CO2e and 193050 t CO2e biomass of carbon and SOC per year respectively. Adoptions of climate smart agricultural practices are affected by different factors such as farming factors, technology inaccessibility, environmental factors, policy design and social expertise, negative attitudes and motivations of farmers, farmers’ socio-demographic factors, and farmers' socioeconomic factors. To reverse the situations, preparation of targeted climate smart agricultural practices to areas that are likely to provide the greatest GHG reduction potential and demonstration of these practices to other areas should be encouraged so that other farmers will learn for similar agro-ecologies.


Introduction
Agriculture is the basic economic sector in Ethiopia in which most population relies for its social and economic development. Its contribution was 46.3% of the national GDP and 90% of foreign exchange earnings of the country (Adem et al., 2018). However, climate variability, change and related extreme events are adversely affecting agricultural production. Climate changes likely result in increased variability in precipitation and increase in temperature (Dendir and Simane, 2019). The variability in precipitation and increase of temperature are due to increases of greenhouse gas (GHG) emissions into the surrounding atmosphere.
It is estimated that agriculture and associated land use changes account for 24% of total global emissions (Niles et al., 2018cited in Smith et al., 2014. However, excluding forestry and other land uses, agriculture contributes approximately 12% of global GHG emissions (IFAD, 2019; Jantke et al., 2020). Methane (CH4) and nitrous oxide (N2O) are the primary GHGs produced by agricultural activities, comprising about 55% and 45% of emissions from agriculture, respectively (IFAD, 2019). In Ethiopia, annual GHG emissions were estimated at 150 Mt CO2e in 2010, with 50% and 37% of these emissions resulting from the agricultural and forestry sectors respectively. In addition, livestock production accounted for more than 40% of the emissions in agriculture (FAO, 2016). Climate change has been caused by human activities like agriculture; particularly small-scale farming is both a contributor to greenhouse gas (GHG) emissions and a victim of the effects of climate change (Abegunde et al., 2019).
Climate smart agriculture (CSA) is an approach to agriculture that sustainably increases productivity, enhances adaptation and mitigates emissions of GHG (IFAD, 2019). On the other hand, there are inadequate research findings on climate smart agricultural (CSA) practices in Ethiopia for the various agro-ecology, soil type, rainfall pattern, farming system, temperature and moisture ranges. At all levels, data on climate smart agricultural (CSA) and conservation agriculture in particular are insufficient (FAO, 2016). Moreover, little research has reported about the status of climate smart agricultural (CSA) practices in mitigation of GHG emissions in Ethiopia. Thus, this review paper aimed to assess climate smart agricultural (CSA) practices in Ethiopia, take up lessons learned elsewhere or in Ethiopia and discuss the contribution of climate smart agricultural practices for mitigation of greenhouse gas emissions, and examine determinant factors of climate smart agricultural practices in mitigation of greenhouse gas emissions. Thus, the paper addresses relevant scientific information's based on evaluation of data collected from different journals, manuals and various report works.

Climate and agriculture
Agriculture is the main sector of the Ethiopian economy. Agriculture in Ethiopia includes crops, livestock, forestry, fisheries, apiculture and other natural resources. It is the most important sector of the national economy and the main source of livelihoods for 85% of the population (FAO, 2016). However, the production and productivity of agriculture in the country is highly vulnerable to climate variability (Dendir and Simane, 2019). Climate variables such as temperature, reduced rainfall, and increased rainfall variability reduces crop yield and threatens food security in low income and agriculture based economies (Gezie, 2019).
The effect of climate change is not only attributing in the reduction of crop yields and incomes but also human health of population who is engaged in agricultural production generally expected to be adverse (Komarek et al., 2019). In Ethiopia, climate change related health problems like mortality and morbidity due to floods and heat waves, vector-borne diseases, water-borne diseases, meningitis, and air pollution-related respiratory diseases are increasing (Simane et al., 2017).
Climate change has caused recurrent droughts and famines, flooding, expansion of desertification, loss of wetlands, loss of biodiversity, and shortage of water resulted in decline of agricultural production (Zegeye, 2018). IPCC (2013) depicts that spatial and temporal distribution of water resources become uneven due to global climate change effects. Other evidence indicates that the major impact of climate change on Ethiopia's economy will result from more frequent occurrence of extreme hydrologic events, which cause losses in both the agricultural and non-agricultural sectors (IFPRI, 2010). As a result, the patterns of climate change data show that rainfall is increasingly erratic with marked seasonal deficits when compared to long term past averages, droughts appear to be increasingly frequent, heavy rainfall events appear to be increasingly frequent, with changes in rainfall patterns, including decreased reliability and less predictability for agricultural activities (USAID, 2015).
Supposing that constant inputs of carbon to soils from vegetation, different estimate predict that expected climate changes for example changes of temperature, precipitation and evaporation will cause significant change in organic matter turnover and CO2 dynamics (Karmakar et al., 2016).
Moreover, Daba et al. (2018) show that soil are complicatedly linked to the climate system through nitrogen, carbon, and hydrologic cycles and in consequence change in climate affect soil processes and properties. Climate change also resulted in increasing of soil, water bodies, and air pollutions and consequently impacts on agricultural production (Arora, 2019). Soil erosion by wind and water are also likely to increase as the result of climate change which removes the most fertile part of top soil (Brevik, 2013). Therefore, climate change impacts of on agriculture have significant consequences on livelihoods, food production, and the overall economy of countries.
Climate changes are affecting particularly those with agriculture-based economies in the developing world like Ethiopia on crop production, livestock productivity, horticultural crops, aquaculture (fish production), and apiculture (Lemi and Hailu, 2019).

Concepts and definitions of terminologies
Climate smart agriculture (CSA) is a tactic for changing and reorienting agricultural systems to support food security under climate change as well as the reduction of GHG emissions from agricultural activities (Abegunde et al., 2019;Komarek et al., 2019). On the other hand, climate smart agriculture (CSA) is a very widely used term that reflects no climate-specific benefits and it contributes significantly to GHG emissions and at the same time is strongly affected by climate change has initiated the exploration of agricultural methods that are aligned with the maintenance of ecosystems (FAO, 2010;SLM, 2017). According to Neufeldt et al. (2013), climate-smart agriculture (CSA) consists of several agricultural practices that sustainably increase productivity, improve resource use efficiency, reduce exposure, vulnerability to climate variability, and reduce GHG emissions from agriculture.
Greenhouse gases (GHGs) emission is the release of gases in the form of carbon dioxide; methane and nitrous oxide are enormously into the atmosphere through these major sources such as deforestation, automobile, agriculture, industry, and organic waste (Arfin et al., 2015).
Emissions of greenhouse gases (GHGs) is the most important driver of human induced climate change (Jantke et al., 2020). Whereas climate change mitigation consists of actions to limit the magnitude or rate of long term global warming and its related effects. Climate change mitigation generally involves reductions in anthropogenic emissions of greenhouse gasses (GHGs).

Sources of GHG emissions from Agriculture
Ethiopia is one of the world's lowest emitters of GHG emissions, ranking 182 of 188 countries on per capita emissions and contributing only 0.27% of global emissions (MOFAN, 2018).
Today's per capita emissions of less than 2 t CO2e are modest compared with the more than 10 t per capita on average in the European Union (EU) and more than 20 t per capita in USA and Australia (Zegeye, 2018).
According to Engdaw (2020), except land use and land cover changes in forestry, Ethiopia has shown increasing trends of emission in most sectors. However, land use and change and forestry is the first leading sector that has contributed to the largest greenhouse gases emission in the country (Figure 1). Figure 1. Trends of greenhouse gas emission in terms of sectors   (Engdaw, 2020) Having an average emission of 50739.7 GgCO2e, land use and land cover change and forestry is the largest sector that contributes to greenhouse gas emissions in Ethiopia. The agricultural sector played the second largest role with an average emission level of 47093.63 GgCO2e.
Following the above two sectors, the energy sector that ranked third has contributed an emission of 17670.13 GgCO2e. Other sectors like waste, industrial, and international bunkers have contributed a trivial amount to the country's greenhouse gas emissions, with average greenhouse gas emissions of 3081.21 GgCO2e, 881.21 GgCO2e, and 458.65 GgCO2e, respectively (Engdaw, 2020).
In Ethiopian agriculture in 2012 for instance, the major sources GHG emissions are indicated in Figure (2). The largest proportion of emissions results from enteric fermentation (53%) followed by manure left on pasture (37%), both of which are related to livestock production. But, the least emitters in Ethiopian agriculture are rice cultivation, burning crop residues, manure applied on soil, and crop residues (FAO, 2016). Moreover, the share of GHG emission from urban production system was 58.4% compared to 22.14% mixed crop-livestock and 18.6% pastoral production system (Berhe and Bariagabre, 2020). Their study also shows 83.42% CH4 was emitted from the systems. The rest 16.6% of the production systems was constituted by CO2 and N2O GHG gases (Table 1). Notes: PPS: pastoral production system, MLPS: mixed crop-livestock production system and UPS: urban production system

Climate smart agricultural practices in Ethiopia
Climate smart agricultural (CSA) practices are practices that sustainably increase productivity, enhance resilience, remove GHGs, and enhance achievement of national food security and  (Table 2).

Mitigation potential of climate smart agricultural practices for GHG emissions
Agriculture can play an important role in climate change mitigation while contributing to increased food security and reductions in rural poverty (FAO, 2012). Widespread adoption of climate smart agriculture (CSA) has the potential to greatly mitigate agricultural greenhouse gas (GHG) emissions by increasing soil organic carbon (SOC) stocks and decreasing nitrous oxide (N2O) emissions (McNunn et al., 2020). According to IFAD (2019), combination of the adoption of climate smart agricultural (CSA) practices such as no tillage, increased crop diversity and retaining crop residue on farm have a mitigation potential/or increased SOC in non-flooded crops that change in significant ton of CO2e ha -1 year -1 . In addition, a mitigation potential of CH4 in reduced irrigation of paddy rice farms was also changed in ton CO2e ha -1 year -1 (Figure 3).
Mitigation practices that increase animal productivity generally also increase emissions but decrease CH4 per unit of animal product (emission intensity). For instance, Thornton and Herrero (2010) found that productivity enhancing interventions in the tropics could reduce emission   (Teklewold et al., 2019). Education status of the farmers and access to extension and weather information can also influence the likelihood of adopting these practices (Issahaku and Abdulai, 2019). Diallo et al. (2019) show that adoption of various climate smart agricultural (CSA) strategies was significantly influenced by socioeconomic, infestation of pests, credit access, institutional and climate related factors. Moreover, several factors, including household characteristics, plot characteristics, market access and major climate risks are found to affect the probability and level of adoption of the various climates smart agricultural (CSA) practices (Aryal et al., 2018).

Conclusions
In Ethiopia, several traditional and adopted climates smart agricultural (CSA) practices carried out by farmers in different agro-ecologies. However, little research information is available for different stakeholders for wider scale out and scale up of the technologies. Among the climate smart agricultural (CSA) practices, agroforestry, conservation agriculture, intensive livestock husbandry, integrated soil fertility management, area closure for restoration of wetlands and degraded lands, participatory forest management practices are the best practices that sustain the ecosystem services, mitigation of greenhouse gases (GHGs), and ultimately improve incomes of households and alleviate poverty in the country.
Combinations of the best adopted climate smart agriculture practices have high potential in mitigation of greenhouse gases. Integration conservation tillage practices with crop diversity on the farmlands play a great role in reduction of GHG emissions. Moreover, enhancing the productivity of livestock could also reduce the intensity of GHG emissions into the atmosphere.
But, different adoptions of climate smart agricultural practices are affected by different factors have implications of continuous emissions of GHGs.
To reverse the situations of climate change, so many adaptation options should be designed. For instance, adoption of climate smart agricultural (CSA) technologies, farmers are encouraged to join community farmer groups to enhance extension service provision through these groups. For extension services, farmers that are using the best traditional and adopted climate smart agricultural (CSA) practices should be clustered for the purpose of agricultural production activities and mitigation of GHG on their farm plots. These farmers can be used as model farmers for agriculture and natural resources management practices. Preparation of targeted climate smart agricultural (CSA) practices to areas that are likely to provide the greatest GHG reduction potential and demonstration of the practices to other areas should be encouraged so that other farmers will learn for similar agro-ecologies. In addition, further multidisciplinary researches on climate smart agricultural (CSA) practices should be carried out to select the best technologies at different stakeholder levels in the country.