Interaction between Biochar Sources and Phosphorus Rates on Maize Growth and Yields in Acrisols and Ferralsols of Bungoma County, Western Kenya

Large proportion of phosphate fertilizer applied to acrisols and ferralsols soils reacts with aluminum (Al) and iron (Fe) to become unavailable for plant uptake. Biochar has been proposed to increase the bioavailability of phosphorus and other nutrients in the soil. The study aimed to increase maize production in low phosphorus (P) soils by evaluating the availability of phosphorus (P) in soils amended with different sources of biochar mixed with different rates of phosphorus in Acrisols and Ferralsols. Biochars were produced from three sources of feedstock: sugarcane bagasse (SB) from Butali sugar factory, wood sawdust (WS) from sawmills within Kakamega town and coffee husk (CH) from Kimukung’i coffee factory in Bungoma county. The feedstocks were pyrolysed using fabricated kilns at Kalro Kakamega. The agronomic evaluation of the fertilizers was carried out in two successive seasons of long rains and short rains of 2023 on maize crops Zea mays l.) In Kibabii site (Acrisols) and Chwele site (Ferralsols) field experiment using a split plot design with three replications. Biochar sources formed the main plots and the subplots were assigned phosphorus (P) rates. The treatments consisted of three sources of biochar (wood sawdust (WS), sugarcane bagasse (SB), coffee husk (CH) and three fertilizer use recommendation project (FURP) phosphorus (P) rates (0, 13, and 26 kg P/ha) on two soil types (Acrisols and Ferralsols). Treatments were applied simultaneously in plots measuring 2.5 m x 4.5 m in all the sites. Maize hybrid 513 at seed rate of 125 kg /ha was planted at a spacing of 75 cm x 25 cm giving a maize population of 53,333 per hectare. Nitrogen fertilizer was applied at the rate of 75kg/ha-1 Nitrogen in two split applications of 35 kg/ha-1 Nitrogen at planting and 40 kg/ha-1 Nitrogen as topdressing at mid vegetative stage per season. Phosphorus rates and biochar sources interactions on maize grain yields were significant differences (P≤0.05). Maize stover and grain yields in Kibabii and Chwele was significantly high under a combination of coffee husks biochar with 26 kg/ha-1 phosphorus treatment. The study concludes that the interaction of biochar sources and phosphorus (P) rates was highly significant in Ferralsols soils and not significant in Acrisols soils. This may be due to chelation of sesquioxides in ferralsols which enhances fixed phosphorus release thereby leading to improved crop development.