Nitrogen Losses and Enrichment of Soil and Sawdust Coverings during Composting of Poultry Manure

Aims: Composting poultry manure is an effective way of enhancing its nutrient content and reduce nutrient losses. There is the need to reduce gaseous nutrient losses during composting through the use of covering materials. Assess the level of chemical enrichment of soil and sawdust used as covering materials; and identify the most suitable medium that can best perform as a covering material during composting of poultry manure.

Materials and Methods: Experiments were set up to examine the changes in the chemical properties of soil and sawdust used as covering material for composted poultry manure. Five treatments – no covering, layers of 2.8 kg soil, 5.6 kg soil, 0.9 kg sawdust, and black polythene sheet on 5.28 kg broiler and layer manure heaps with four replications were arranged in a completely randomized design. Samples were taken from the manure piles and the soil and sawdust covering materials for chemical analysis at 3, 6 and 9 weeks after composting.

Results: The pH, N, P, K, Na and Ca, in both soil covers increased as time elapsed, whereas the Mg and C/N ratios of the soil coverings decreased with time. With regards to the broiler manure, however, the pH and the nutrient content of the two levels of soils used as cover increased at all the stages of composting. Composting of both poultry manures resulted in the improvement of the chemical properties of both sawdust and soil coverings. The enrichment ratio of N was greater in the 5.6 kg soil than the 2.8 kg soil covering. Additionally, the 5.6 kg soil covering was highly efficient (P = .05) in reducing N losses by 57 and 83.85% from the broiler and layer piles, respectively. In general, the 5.6 kg soil was the most effective covering material.