Soil greenhouse gas fluxes and net global warming potential from two maize farming practices in the Bamenda highlands, Cameroon.

Farming practices used in maize crop production are thought to modify greenhouse gas (GHG) emissions from the soil particularly methane (CH), carbon dioxide (CO), and nitrous oxide (NO). The quantities of these GHG fluxes have rarely been estimated from smallholder farms in Sub-Saharan Africa. We estimated the quantities of GHG fluxes and Global Warming Potential (GWP) from the Push-Pull Technology (PPT) and Tillage with the Formation of Ridges (TFR) farming systems at the University of Bamenda, Cameroon. Greenhouse gases were sampled bi-monthly from April to Early August 2020 using the static chamber technique. The experiment followed a split-plot randomized complete block design with two replicates and three planting distances (1 m, 1.5 m, and 2 m) used as treatments. Mean cumulative CH (5.39 kgCH-Cha) and NO (1.03 kgNO-Nha) emissions under TFR were significantly higher (P < 0.05) than mean CH (3.59 kgCH-Cha) and NO (0.52 kgNO-Nha) emissions under PPT system. Mean net-GWP under PPT followed the trend 2 m (-267.61 ) < 1.5 m (-75.76 ) < 1 m (-24.95 ) while under TFR, net-GWP was ordered 1 m (0.38 ) < 1.5 m (85.29 ) < 2 m (288.41 ) with significant differences between them. Maize grain yields under PPT were in the trend 1 m (0.81 ) < 2 m (0.85 ) < 1.5 m (0.92 ) with a significant difference (P < 0.05) between 1 m and 1,5 m treatments. While under TFR, the trend was 2 m (0.56 ) < 1 m (0.77 ) < 1.5 m (0.80 ) with significant difference between 1.5 m and 2 m (P < 0.05). On average, PPT was a sink to GWP (-122.77 ) and revealed higher (P < 0.05) yields (0.86 ) than TFR (0.71 ) which was a source of GWP (124.69 ). Therefore, a PPT practice of 1.5 m planting distance is recommended in Sub-Saharan Africa to enhance food productivity while mitigating global warming by minimizing soil greenhouse gas emissions.