Effects of different organic residues on carbon sequestration, nutrient availability in soil and maize yields at Katumani, Machakos county Kenya
Mbaluka, Titus Luta
MetadataShow full item record
Reduced farm productivity in smallholder farms is the principal cause of food insecurity in semi-arid parts of Kenya. This is mainly attributed to soil fertility depletion, land degradation, low soil moisture and climate change. Climate change due to increased carbon dioxideemission into the atmosphere has impacted negatively on the food productivity in Africa.The objectives of this study were: 1) to determine the effect of different organic residues on soil carbon accumulation in soil. 2) to determine the effect of organic residues on the availability of nutrients into the soil, and 3) to determine the effect of different organic residues on maize growth and yields. Field studies were carried out in two seasons (2011/2012 short rains and 2012 long rains) at Kenya Agricultural Research Institute (KARI) – Katumani Dry land Research Centre in Machakos County. Maize residues and compost manure were used, under different application methods and a control where no organic residue was applied. This constituted seven treatment combinations as follows; 1) Control, no organic residue application; 2) 10 ton/ha compost, surface application; 3) 10 ton/ha compost, incorporated application; 4) 5 ton/ha maize stover, surface application; 5) 5 ton/ha maize stover, incorporated application; 6) 5 ton/ha maize stover, 10 ton/ha compost, surface application; 7) 5ton/ha Maize stover, 10 ton/ha compost, incorporated application). The seven treatments were laid out in a randomized complete block (RCBD) design with 3 replications. Soil samples were collected from 0-20cm and 20-40cm depths before planting, at six weeks after planting and at harvest. The soil samples were analyzed for total C, total N, soil pH, available P, Mg, Ca, Na, K and CEC. Maize grain yield and total dry matter was measured. Statistical analysis of data was done using analysis of variance (ANOVA) and means separated using LSD at p=0.05. Results of this study showed that total soil organic carbon increased with application of organic residues. Treatments that had 5ton/ha maize stover and 10 ton/ha compost, incorporated recorded the highest soil carbon accumulation of 0.36 Mg C/ha and 0.39 Mg C/ha at the end of season one and two, respectively while the control decreased by 0.02 Mg C/ha in season 1 and 0.03 Mg C/ha in season two. Nutrients concentrations in the soil were found to increase with application of organic residues where by incorporated 5 ton/ha maize stover and 10 ton/ha compost treatment recorded the highest concentrations of most nutrients in the soil. Maize yields increased with the application of organic residues. Treatments that had 5 ton/ha maize stover and 10 ton/ha compost under incorporated application gave the highest maize grains which was 145% more, compared to the control in season one and 248% in season two. In conclusion combining 5 ton/ha maize stover and 10 ton/ha compost under incorporated application could be a promising soil fertility management strategy for improved carbon storage in soils and for increased maize productivity.