Soil carbon stocks and projected changes according to land use and management: a case study for Kenya

Abstract. Soil organic (SOC) and inorganic carbon (SIC) stocks of Kenya were determined using four different methods to provide baseline data. The assessments used an updated version of the 1:1 M soil and terrain database for the country. Estimates for national SOC stocks to 1 m depth ranged from 3452 to 3797 Tg C. The findings highlight the need for comprehensive databases of soil and terrain data of good quality that consider more than one representative profile per soil component. The 95% confidence limits for the median, area-weighted SOC content were largest in the humid highlands (15.4–15.7 kg C m⁻²) and smallest in the hot arid zone (4.4–4.5 kg C m⁻²). Conversely, for SIC these values were largest in the arid zone (4.3–4.5 kg C m⁻²) and smallest in high rainfall areas (<0.1 kg C m⁻²). Many croplands in Kenya have been over-exploited, resulting in nutrient depletion and loss of organic matter. The SOC gains considered ecologically and technically feasible upon improved management of croplands were estimated at 5.8–9.7 Tg C over the next 25 years. This corresponds to an estimated annual mitigation potential of 5–9% of Kenya's CO₂-C emissions from fossil fuels, cement manufacturing and land use change for 1990.