Smallholder cropping systems contribute limited greenhouse gas fluxes in upper Eastern Kenya

The contribution of smallholder farming systems to the National greenhouse gas (GHG) budget is missing in most developing countries, including Kenya. Data on the contribution of smallholder cropping systems to the GHG balance is essential for realising Sustainable Development Goal 13 on climate action, i.e., on nationally determined contributions (NDCs) and in compliance with the Paris Agreement. Do smallholder farming systems act as nature-based solutions for greenhouse gas emissions reduction? This study evaluated GHG emissions from cropping systems under on-farm smallholder farming conditions. We had five cropping systems on two smallholder farms: sole maize, maize-bean intercrop, coffee, banana, and agroforestry. Gas samples were collected using three static chambers per cropping system. The gas samples were analysed using gas chromatography (GC) fitted with a 63Ni-electron capture detector (ECD) for N2O and flame ionisation detector (FID) for CH4 and CO2 using N as carrier gas. Cumulative annual fluxes of (CH4, N2O, and CO2) varied significantly in farms one and two across the cropping systems. The cumulative soil GHG fluxes ranged from -1.34kg CH4single bondC ha−1 yr−1 under agroforestry to -0.77kg CH4single bondC ha−1 yr−1 under banana for CH4, 0.30kg N2Osingle bondN ha−1 yr−1 to 1.23kg N2Osingle bondN ha−1 yr−1 for N2O and 5949kg CO2single bondC ha−1 yr−1 to 12,954kg CO2single bondC ha−1 yr−1 for CO2. The maize grain yields ranged from 0 to 3.38 Mg ha−1. The N2O yields scaled emissions ranged from 0.10 to 0.26g kg−1 maize and 0.68 to 1.30g kg−1 beans. Smallholder farmers in Upper Eastern Kenya contribute a limited amount of soil GHG emissions and thus could act as a nature-based solution for lowering agricultural emissions

Soil Organic Carbon Stocks under Different Land Utilization Types in Western Kenya

The up-surging population in sub-Saharan Africa (SSA) has led to the conversion of more land for agricultural purposes. Resilient land utilization types that input carbon to the soil are key in enhancing climate change mitigation. However, there are limited data on different land utilization types’ contribution to climate mitigation through carbon input to soils. The study aims to quantify carbon stock across different land utilization types (LUT) practiced in Western Kenya. The following land utilization types were studied: agroforestry M (agroforestry with Markhamia lutea), sole sorghum, agroforestry L (agroforestry with Leucaena leucocephalaI), sole maize, and grazing land replicated thrice. To determine soil bulk density, SOC concentration, and soil carbon stock, soil samples were collected at depths of 0–5, 5–10, 10–20, and 20–30 cm from different LUTs. A PROC ANOVA was used to determine the difference in soil bulk density, SOC, and SOC stock between different LUTs and depths. The four variables differed across the LUTs and depths. A high soil bulk density was observed at 0–5 cm under grazing land (1.6 g cm−3) and the lowest under agroforestry M (1.30 g cm−3). Conversely, the soil bulk density was low at 20–30 cm under grazing land. The 0–5 cm depth accounted for a high share of SOC and SOC stock under Agroforestry M, while the 10–20 and 20–30 cm depth accounted for the high share of SOC stock under agroforestry L. The study showed differences in SOC across the different depths and LUTs. The findings highlight that agroforestry L and agroforestry M are promising interventions toward climate mitigation through carbon induction to soils

Smallholder cropping systems contribute limited greenhouse gas fluxes in upper Eastern Kenya

The contribution of smallholder farming systems to the National greenhouse gas (GHG) budget is missing in most developing countries, including Kenya. Data on the contribution of smallholder cropping systems to the GHG balance is essential for realising Sustainable Development Goal 13 on climate action, i.e., on nationally determined contributions (NDCs) and in compliance with the Paris Agreement. Do smallholder farming systems act as nature-based solutions for greenhouse gas emissions reduction? This study evaluated GHG emissions from cropping systems under on-farm smallholder farming conditions. We had five cropping systems on two smallholder farms: sole maize, maize-bean intercrop, coffee, banana, and agroforestry. Gas samples were collected using three static chambers per cropping system. The gas samples were analysed using gas chromatography (GC) fitted with a 63Ni-electron capture detector (ECD) for N2O and flame ionisation detector (FID) for CH4 and CO2 using N as carrier gas. Cumulative annual fluxes of (CH4, N2O, and CO2) varied significantly in farms one and two across the cropping systems. The cumulative soil GHG fluxes ranged from -1.34kg CH4C ha−1 yr−1 under agroforestry to -0.77kg CH4C ha−1 yr−1 under banana for CH4, 0.30kg N2ON ha−1 yr−1 to 1.23kg N2ON ha−1 yr−1 for N2O and 5949kg CO2C ha−1 yr−1 to 12,954kg CO2C ha−1 yr−1 for CO2. The maize grain yields ranged from 0 to 3.38 Mg ha−1. The N2O yields scaled emissions ranged from 0.10 to 0.26g kg−1 maize and 0.68 to 1.30g kg−1 beans. Smallholder farmers in Upper Eastern Kenya contribute a limited amount of soil GHG emissions and thus could act as a nature-based solution for lowering agricultural emissions