Rangelands cover approximately 85% of Kenya’s land mass and is a major resource for livestock farming with a considerable potential to mitigate climate change, yet these lands are stressed differently by various management. Our study aimed at determining the influence of grazing management systems (rotational, continuous and ungrazed) on soil organic carbon stocks in Yoani ranch located in the southern rangelands of Kenya (2016). This research was conducted on a commercial grazing ranch, a section of it was converted from continuous grazing into rotational grazing and has been under rotational grazing for 11 years during the time the research was conducted. Within the same ranch, there was a section with similar geomorphology and soils as the rotationally grazed which was not converted and has been continuously grazed for over 30 years to represent the continuous grazing system. The ungrazed area consists of an abandon section of the ranch for more than 30 years due to a deep gully which was formed by gully erosion creating an isolated area inaccessible by livestock. Soil samples were taken up to a depth of 1.2m, at an interval of 0-10, 10-20 cm, 20-30 cm, 30-60 cm, 60-90 cm and 90-120 cm. The difference between soil sampling depths is because the upper layer between 0-30 cm is more dynamic with respect to soil microbial activities which can be influenced by grazing as compared to the deeper depths along the soil profile. The ungrazed site recorded significantly (P<0.5) higher soil organic carbon concentrations than rotational and continuously grazed sites for all soil layers up to 1.2m depth. The rotationally grazed site had higher soil organic carbon concentrations across depths compared to continuously grazing system which was attributed to grazing management effects. تفاصيل المقالة

Livestock grazing practices in rangelands are being recognized as management tool for environmental protection and increased livestock productivity. Continuous grazing has been largely reported to reduce pasture productivity and increase environmental degradation. Rotational grazing is an alternative to continuous grazing and is considered to reduce negative environmental effects and provide quality pastures and browse ensuring availability of quality feed for animals while conserving the environment. This study was conducted in a semi-arid grassland in the south eastern rangelands of Kenya which is primarily used for cattle production to establish how grazing management system affects herbaceous biomass yield, cover, plant species richness and diversity (in 2016). Quadrat method was used to collect vegetation samples. In each plot, a 100 m2 sub- plot was demarcated and five 1×1m quadrats laid out. A quadrat was placed at each of the four corners of the 100m2 plot and the 5th quadrant placed at the center of the plot. Herbaceous biomass production was significantly higher (p≤0.05) in rotationally grazed areas compared to both continually grazed and ungrazed areas with average values of 7037, 2478 and 2390 Kgha-1 respectively. Similar trend was obtained for vegetation cover. Vegetation cover of herbaceous plants was significantly higher under rotationally grazed areas compared to both continually grazed and ungrazed areas with average values of 55, 37 and 27%, respectively. There was no significant difference for plant species richness and diversities and between the three sampling blocks. However, the highest values of both latter traits were obtained in rotationally grazed areas, followed by continually and ungrazed areas. Improved biomass yields and high species diversity in rotation grazed areas was largely attributed to the flexibility in the management in which grazing frequency, durations and the rest periods are efficiently controlled compared to continuous grazing areas. This study concludes that rotation grazing allows flexibility of animal utilization of pastures resulting to enhanced soil water retention, increased species diversity; richness and vegetation cover which increase biomass yields. تفاصيل المقالة

Rangeland cover approximately 85% of Kenya’s land mass and is a major resource for livestock farming with a considerable potential to mitigate climate change, yet these lands are stressed differently by various management. Our study aimed at predicting the long-term changes in Soil Organic Carbon (SOC) in grazing lands of Kenya under different grazing management systems (rotational, continuous and ungrazed), for a 50-year period using RothC 26.3. This research was conducted on a commercial grazing ranch which practices the two grazing management systems. Soil samples were collected at the depths of 0-10, 10-20 and 20-30 cm for the determination of soil organic carbon concentrations and bulk densities, results were later used for running the RothC model. The predicted results showed that the rate of SOC stock [t/ha] was higher under rotational grazing system in comparison to ungrazed and continual grazing system for the modelling period of 2015-2064. In the absence of grazing, the system was predicted to accumulate 19.22 Mg C ha-1 of SOC at the rate of 0.369 Mg C ha-1yr-1, whereas rotational grazing system was predicted to accumulate 30.46 Mg C ha-1 at the rate of 0.61 Mg C ha-1yr-1. The continual grazing management system resulted in the accrual of 18.49 Mg C ha-1 at the rate of 0.37 Mg C ha-1 yr-1 over 50 years. Thus, rotationally grazing management system have the potential of accumulating soil organic carbon in semi-arid grasslands. تفاصيل المقالة

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. تفاصيل المقالة