Greenhouse Gas Fluxes from Selected Soil Fertility Management Practices in Humic Nitisols of Upper Eastern Kenya

Abstract

We quantified the soil carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes of five soil fertility management practices (inorganic fertilizer (Mf), maize residue + inorganic fertilizer (RMf), maize residue + inorganic fertilizer + goat manure (RMfM), maize residue + tithonia diversifolia + goat manure (RTiM), and a control (CtC)) in Kenya’s central highlands using a static chamber method from March 2019 to March 2020. The cumulative annual soil CH4 uptake ranged from −1.07 to −0.64 kg CH4-C ha−1 yr−1, CO2 emissions from 4.59 to 9.01 Mg CO2-C ha−1 yr−1, and N2O fluxes from 104 to 279 g N2O-N ha−1 yr−1. The RTiM produced the highest CO2 emissions (9.01 Mg CO2-C ha−1 yr−1), carbon sequestration (3.99 Mg CO2-eq ha−1), yield-scaled N2O emissions (YSE) (0.043 g N2O-N kg−1 grain yield), the lowest net global warming potential (net GWP) (−14.7 Mg CO2-eq ha−1) and greenhouse gas intensities (GHGI) (−2.81 Kg CO2-eq kg−1 grain yield). We observed average maize grain yields of 7.98 Mg ha−1 yr−1 under RMfM treatment. Integrating inorganic fertilizer and maize residue retention resulted in low emissions, increased soil organic carbon sequestration, and high maize yields.