Effects of Grazing Management on Greenhouse Gas Emissions in Southern Rangelands of Kenya

Abstract

Rangelands ecosystems play a critical role in regulating the emission and uptake of the most important Greenhouse Gases (GHGs) such as CO2, CH4, and N2O. However, the effects of grazing management on GHG fluxes in the semi-arid lands of East Africa remain unclear. The present study compared the effects of three grazing systems on cumulative CO2, CH4, and N2O fluxes in the semi-arid grazing land ecosystem in Yohani ranch Makueni County, Kenya. The study followed a pseudo-replication design in which there were three treatments: 1) Continual grazed, 2) rotational grazed and 3) and ungrazed. Greenhouse gas samples were collected using the static chamber method for a period of three months covering the dry and wet season as well as a transition period. Cumulative soil CO2 fluxes were highest in continual grazing system (2357±123.9 kg ha-1 3 months), followed by rotational grazing (1285±123.9 kg ha-1 3 months) and lowest in the ungrazed (1241±143 CO2 kg ha-1 3 months), respectively. The three month cumulative N2O and CH4 fluxes were also highest in continual grazing and lowest in ungrazed site 677.9±130.1, 208.6±127.3 and 162.2±150.3 (g ha-1 3 months) and CH4, 232.7±126.6, 173.1±126.6 and 80±46.2 (g ha-1 3 months) respectively. The results suggest that the continual livestock grazing system increases emissions of GHGs compared to rotational grazing.