Nitrogen Mineralization in Selected Solid Waste Dumpsites in Port Harcourt, Nigeria.

Organic wastes in selected waste dumpsites in Port Harcourt were successively incubated with sandy-loam soils for days at 27°C, under aerobic conditions. The results showed marked decrease in total nitrogen in the organic wastes which was observed as loss of nitrogen. The process of nitrification and incorporation of (NH4)2SO4 affected the pH which ranged from 5.9 to 7.9. The cumulative mineral nitrogen released increased with incubation periods and the rate of organic application up to 28th day, with a maximum release of 456.40ppm at a rate of 61MT/ha organic application. The release of mineral N decreased on the 56th day with a minimum of 177.80ppm at a rate of 60MT/ha of organic fertilizer only. An enriched organic. Waste soil and organic waste treated soil had a boosting effect on the release of mineral nitrogen. The amount of mineral nitrogen released was higher for (NH4)2SO4 fertilizer treated soil than for organic waste treated soil. The mineralization rate was found to decrease with increasing age of the waste dumps. It was therefore recommended that organic wastes should be sorted and composted for use as organic fertilizers to augment inorganic fertilizer.