Environmental greenhouse gas hotspots and climate change adaptation in smallholder sorghum cropping systems in Siaya county, Kenya

Abstract

Sorghum (Sorghum bicolor L.) is an essential drought-resistant crop that could enhance food security. However, its productivity remains relatively low in Kenya. Efforts to increase sorghum productivity through the application of external inputs could increase greenhouse gas (GHG) emissions. The study aimed to assess environmental GHG emission hotspots, effects of minimum tillage and inorganic fertilizer adoption on sorghum yields, and the determinants of adopting climate-smart agriculture and climate change adaptation practices. The study employed a cross-sectional survey of 300 smallholders in Siaya County, Kenya. Principal component analysis and hierarchical clustering were used in farm typologies construction. Using Cool Farm Tool software, a carbon footprint assessment approach was performed to identify environmental GHG emissions hotspots. One-way analysis of variance was used to test the influence of farm types on sorghum yields, GHG balance, carbon footprint, and monetary footprint in SAS 9.4 software. Descriptive statistics were used to describe the survey data. The impact of minimum tillage and inorganic fertilizer adoption were analyzed using propensity score matching and endogenous switching regression. Socioeconomic, institutional and biophysical determinants of adopting climate-smart agricultural practices (CSAPs) were analyzed using multivariate and ordered probit regression. Binary and Poisson regression models were used to evaluate the determinants of adopting climate change adaptation strategies. The results showed five farm types. The study showed that sorghum cropping systems were net sinks of soil GHGs. The GHG balance, carbon footprint, and monetary footprint significantly varied across the farm types at p=0.025, p=0.018, and p=0.004, respectively. The GHG balance ranged from -818.76 kg CO2 eq. ha-1 in manure intensive and low fertilizer intensity small farms to 174.29 kg CO2 eq. ha-1 in fertilizer intensive and moderate manure application rates on small farms. Adoption of minimum tillage and inorganic fertilizer improved sorghum yields. The study showed both complements and substitutes between CSAPs. The multivariate probit analysis revealed that the household head's gender, education, age, family size, contact with extension agents, weather information, arable land, livestock owned, perceived climate change, infertile soil, and persistent soil erosion influenced CSAPs adoption. Gender, arable land, livestock owned, soil fertility, and constant soil erosion were crucial determinants of CSAPs adoption intensity. Membership in agricultural associations, study location, progressive farming, literacy, remittance, access to credit, farm size, weather forecast information, and perceived climate changes significantly determine the adoption of climate change adaptation strategies. The study revealed that the judicious integration of inorganic fertilizers with animal manure could significantly improve sorghum yields while reducing yield-scaled greenhouse gas emissions. The findings on adopting agricultural innovations have incredible implications on rural livelihood. Enhanced productivity could promote food security and improve purchasing power, thus enhancing smallholder farmers’ capacity to cope with declining soil fertility and climate change-related challenges.