Projected Changes in Soil Organic Carbon Stocks over a 50-Year Period under Different Grazing Management Systems in Semi-Arid Grasslands of Kenya

Document Type: Research and Full Length Article

Authors

1 Department of land resource and Agricultural technology, University of Nairobi

2 Faculty of Agriculture, University of Nairobi

3 Land resource management and agricultural technology, faculty of agriculture, university of nairobi

4 Land resource management and Agricultural technology, faculty of agriculture, university of Nairobi

Abstract

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.

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Articles in Press, Accepted Manuscript
Available Online from 12 May 2020
  • Receive Date: 02 May 2019
  • Revise Date: 01 May 2020
  • Accept Date: 12 May 2020