On farm assessment of carbon stocks under sub optimal and optimal input management in Mpongwe and Chisamba districts of Zambia

Abstract

Soil management in agriculture can either contribute to further carbon emissions or carbon sequestration depending on the agricultural practices implemented. Conservation Agriculture (CA) is one of the promising practices being promoted for reducing the greenhouse gas effect in the face of climate change. This study sought to assess the amount of soil organic carbon (SOC) in CA and Conventional Tillage (CT) cropping systems under suboptimal and optimal input management in Mpongwe and Chisamba districts. Soil samples were randomly collected at a depth of 20 cm to assess the C-stock in fields which have been under CA/CT between 3 and 7 years under suboptimal and between 12 and 18 years under optimal input management. Changes on selected soil properties over time were determined using standard laboratory procedures. The amount of carbon sequestered was assessed using the adjusted Land Use Land-Use Change and Forestry (LULUCF) model. CA fields had sequestered 1,424 Kg SOC /ha,yr while the CT had 392kg SOC/ha,yr, representing a threefold difference. At GART SOC was 63,180kg/ha after 15 years of CA compared to 50,622kg/ha under CT over the same period. These findings suggest that CA can mitigate the effects of climate change by reducing the carbon emission resulting from the crop production practices. Further, there were significant differences between C-stocks under the 18 and 12 years CA fields under Faidherbia albida trees at GART. The results also showed increased pH values under the eucalyptus plantation compared to the other fields at GART suggesting that pH increases when land use is changed from agriculture to forestry.

Keywords: Carbon, sequestration, emissions, conservation agriculture.