Mitigation of greenhouse gas (GHG) emissions through shade systems and climate-smart soil fertility interventions in cocoa landscapes in the Semi-deciduous ecological zone of Ghana

Minimizing nitrogen losses, improving fertilizer management practices, and adopting sustainable agricultural practices are essential for mitigating the climate impacts of fertilizer use and promoting agricultural sustainability. This study aimed to address greenhouse gas emissions in cocoa landscapes in Ghana by examining the impact of shade systems and soil amendments on the release of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and overall global warming potential (GWP). The study consisted of two factors; shade systems (no shade and medium shade) and soil amendment (No amendment (T1), mineral fertilizer alone (T2), mineral fertilizer + biochar (T3), ½ mineral fertilizer + compost without rock phosphate and ½ mineral fertilizer + compost with rock phosphate (T5)). The shade system did not significantly influence CO2, CH4, and N2O emissions. Emissions of CO2 were higher in the amended compared to the non-amended plots in the two eco-zones. Applications of ½ mineral fertilizer + compost (T4 and T5) increased CH4 production in both eco-zones. However, the application of mineral fertilizer alone (T2) and mineral fertilizer + biochar (T3) had varying effects on CH4 emissions from the soil. Greater emissions of N2O were recorded in the amended plots within the two eco-zones compared to the non-amended (T1) plots. Soil water and microbial biomass carbon (MBC) correlated positively with CO2 and CH4 fluxes in the two eco-zones where soil water accounted for 48% of the emissions of CH4 in the moist eco-zones, and MBC was responsible for 54 and 65% in the moist and dry eco-zones respectively, of CH4 emissions. Sole mineral fertilizer application (T2) had the highest GWP,14.70 and 13.56kg CO2 eq ha-1 yr-1 x 105 in both the moist and dry eco-zone respectively. This study contributes valuable insights into the potential of shade systems and soil amendments to mitigate greenhouse gas emissions in cocoa landscapes in Ghana, thereby fostering the transition towards more sustainable and climate-resilient cocoa production systems.