Effects of Neem Extracts on Soil Properties, Microbial Populations and Leaf Area of Fluted Pumpkin (Telfairia occidentalis)

摘要

Potted followed by field experiments were set up to investigate the effects of various neem (Azadirachta indica) extracts on an acid soil physicochemical properties and microbial populations. Telfairia occidentalis was planted to test the impacts of the treatments. The results indicated highly significant positive improvements in soil physicochemical properties. Exchangeable Calcium (Ca), Magnesium (Mg) and other cations were added to the soil, which elicited an improvement of the soil pH and boosted soil fertility. Calcium significantly increased from initial 1.70 to 3.20 cmol kg 1, causing improvement in Effective Cation Exchange Capacity (ECEC) and Base Saturation (BS) statuses of the soil, at more than 60 and 50% ,respectively. Leaf area of Telfairia was significantly improved as it shifted from initial mean of 4.00 to 7.50 cm2. There was generally increase in the population of the carbon degrading organisms with time while free living organisms like Streptococcus sp. and Klebsiella sp. had initial depression in population. Micrococuss sp. was eliminated from the soil. Bacillus sp. increased from 7?106 in the control to 18 ? 106 cfu g-1 at 6 weeks after treatments. It was concluded that crops by-products such as neem extracts are environmentally safe soil amendments and fertility booster.