Soil Properties and Stoichiometry as Influenced by Land Use, Enclosures and Seasonality in a Semi-arid Dryland in Kenya

Agropastoralism and nomadic pastoralism constitute the main land use systems in semi-arid drylands in Kenya. However, limited studies have investigated how land use and management practices and seasonality affect soil properties that alter C, N, and P biogeochemical cycling in African drylands systems. Thus, this study was conducted to determine effects of: (1) sedentary agropastoral land-use system (SAL), (2) semi-nomadic pastoral land-use system (SNL)), (3) pasture enclosures and (4) seasonality on selected soil chemical properties and total C, N, and P stoichiometry in a semi-arid landscape in Kenya. Land use, enclosures, and seasonality affected chemical properties of soils and C, N, and P stoichiometry. Generally, Na, K, Ca, Mg and cation exchange capacity were higher in the dry than wet period. Soil C:N ratios were less than 5, while N:P and C:P ratios were 5–56 and 16–177, respectively. However, ratios of C:N, N:P and C:P were significantly higher in SNL than SAL. The C:P and N:P ratios in both land use systems were highly correlated (r² > 0.70). During the wet season, C:N ratios of soils were higher inside enclosures in both land uses. Higher soil N:P and C:P ratios were observed during dry compared to wet seasons. The N:P and C:P ratios of soils were higher inside and outside enclosures in SAL and SNL, respectively. Land use, enclosures and seasonality exhibited different effects on chemical properties of soils and C:N:P stoichiometry ratios. Perennial vegetation cover in enclosures has a great potential to enhance soil health necessary to support pastoral land-use systems in semi-arid African drylands.