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

Miriam W Githongo,Andreas Fliessbach,Joseph M Macharia,Anne Muriuki,Milka N Kiboi,Collins M Musafiri,Felix K Ngetich

doi:10.3390/su14031938

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.

Highlights

Introduction iationsIncreased worldwide anthropogenic greenhouse gas concentrations have led to an elevated average global temperature and reduced agricultural productivity [1]
A recent study by [17] has reported that these soils have low organic carbon (
Our findings indicated that integrating organic inputs, either sole or mineral fertilizer, significantly increased grain yields, CO2 emissions, and N2 O fluxes while lowering net global warming potential (net Global Warming Potential (GWP)) and greenhouse gas intensities (GHGI) compared with the control

Summary

Introduction

Increased worldwide anthropogenic greenhouse gas concentrations have led to an elevated average global temperature and reduced agricultural productivity [1]. Agriculture accounts for approximately 14 to 17%, 26%, and 30% of the global, African, and Kenyan total GHG emissions, respectively [2,3]. Agricultural land acts as a source and sink of GHGs depending on the particular agricultural management practice [4,5]. Soil GHG fluxes result from complex biological and chemical processes [6]. Agricultural management practices, including the addition of soil inputs, both inorganic and organic, could impact soil GHG emissions. Soil CO2 fluxes are a result of soil respiration, which is the summation of autotrophic (roots and the rhizosphere) and heterotrophic (from macro and microfauna in the soil)

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Conclusion