Enhancing Barley Yield and Biomass in Kenya: The Effects of Local Sediments, Lime Amendments and Straw Return

Soil acidification and low nutrient availability are critical challenges for agriculture in East Africa, often leading to aluminium (Al) toxicity and reduced crop yields. Amending arable land with local sediments has been shown to be a promising strategy to address these issues, although responses have been variable. We investigated the effects of local sediment amendments influenced by volcanic deposits on soil pH, nutrient availability, and barley productivity in field trials conducted in Eldoret, Western Kenya in the first year and compared it to lime amendments and straw return in the second year. Plots were amended with 1% and 3% of two local sediments (from Baringo and Nakuru). The 3% Baringo amendment significantly increased soil pH (from 4.7 to 7.0), enhanced available phosphorus (P) content (from 0.01 mg g⁻¹ to 0.02 mg g⁻¹), and reduced Al availability (from 3.03 mg g⁻¹ to 2.17 mg g⁻¹), resulting in the highest barley yield of 4.7 t/ha (+1061%). In the second year, growth was strongly inhibited by drought periods, but the trends were visible again with Baringo 3%. Similarly, lime at 0.15% improved soil conditions and barley yield (0.91 t ha^-1), though less effectively than Baringo 3% (1.3 t ha^-1). Control and Nakuru, as well as straw return did not improve the soil conditions and yield significantly. These findings highlight the potential of local sediment amendments to mitigate soil acidification and enhance crop productivity, particularly through carbonate dissolution and pH elevation, though outcomes depend on sediment composition and amendment rates.