Abstract
This project studied the effect of compost on soil nitrogen, phosphorus and potassium using cowpea (Vigna unguiculata) seeds. The compost was prepared from fruit and vegetable peels obtained from commercial fruit vendors through aerobic composting process. The physicochemical characterization of the compost containing amendment materials (cow bone, corn cob and palm oil sludge) revealed the following results: pH(8.78 ± 0.16), Electrical conductivity (2505.03 ± 3.56), Moisture content (19.43 ± 1.22), Ash content(50.42 ± 0.76), Volatile matter (49.58 ± 0.76), Organic matter (42.97 ± 0.28), Total organic matter (24.93 ± 0.16), Total nitrogen (1197.70±152.67), Phosphorus (1305.93±281.85), Potassium (50.50 ±0.04) while that of the unamended compost revealed the following results ; pH(7.96 ± 0.00), Electrical conductivity (2316.55±0.25), Moisture content (31.93 ± 2.13), Ash content (20.78 ± 0.02), Volatile matter (79.22 ± 0.02), Organic matter (46.81 ± 2.48), Total organic carbon (25.12 ± 0.59), Nitrogen (884.05±188.65), Phosphorus (618.38±20.70), Potassium (125.6 ± 4.40). The compost was mixed with agricultural soil (loamy soil) in the ratios 1:1 for the unamended compost and soil,1:1 and 3:1 for amended compost and soil and the last pot contained only soil. Pot experiment was carried out with cowpea (Vigna unguiculata) seeds using the above ratios. Analysis for the nitrogen, potassium and phosphorus levels was carried out after 3 days and 19 days of planting. Although no plant growth was recorded after 19 days, there were significant changes in the soil’s nitrogen, potassium and phosphorus levels after 19 days in comparison to what was recorded after 3 days. The soil with 1:1 of unamended compost and soil showed an increase in the nitrogen, potassium and phosphorus after 19 days, the one with 3:1 of amended compost and soil also showed an increase in the nitrogen and potassium level after 19 days but there was a decrease in phosphorus, the one with 1:1 amended compost and soil also showed an increase in nitrogen and potassium level but a decrease in phosphorus level while the one with only soil showed an increase in nitrogen, potassium and phosphorus levels. This research gives an insight on the importance of compost in improving soil nitrogen, phosphorus and potassium levels and also as a suitable soil amendment.
