Influence of Organic and Inorganic Fertilizers on Soil Chemical Properties and Nutrient Changes in an Alfisol of South Western Nigeria

Temporal changes in soil organic matter and other chemical properties influence the availability of nutrients to plants with or without the application of fertilizers. For proper soil management, these changes must be accounted for. Pot experiment was conducted to assess changes in soil organic carbon, pH and soil nutrients using both inorganic and organic fertilizers. The experiment was a 2 x 3 factorial experiment arranged in completely randomized design with three replicates, using five soil samples collected from Abeokuta, Igboora, Ikenne, Kobape and Odeda of Nigeria. Maize (var. SUWAN 1) was planted in the pots and grown for three consecutive cycles of six weeks each. Soil samples were analyzed for total N, soil organic carbon (SOC), NH4+-N, NO3--N, available P, K, Na, Ca, Mg and pH at pre-planting, at 6 weeks after planting (WAP). The results showed a decrease in average SOC and total N with time in all the soil types. Decrease in total N with time which could be attributed to the crop utilization, ammonia volatilization and bacteria denitrification was also observed. Addition of poultry manure improved the K, Ca, Na, Mg content of the soil and also present a potential to act as lime especially in short time. Combined application of poultry manure and NPK fertilizer reduced susceptibility of soils considered to acidification. Complementary application of 10 t ha-1 of poultry manure with 120 kg ha-1 NPK 20-10-10 proved to improve the soil fertility.