International Symposium on
Drylands Ecology and Human Security
Decomposition and Nutrient Release of Different Organic Residues
*Mubarak, A.R. and Dawi, B.S.I.
Desertification and Desert Cultivation Studies Institute, University of Khartoum, Shambat, Sudan
Plant litter is important in maintaining soil organic carbon levels as well as for nutrient cycling especially in the semi-arid tropics. A field experiment (for 16 weeks) was carried in western Omdurman, Sudan to monitor decomposition and nutrient release from residues of Mesquite (Prosopis spp), Mahogany (Khaya senegalensis) and Neem (Azadirachta indica). Fresh leaves litters were placed inside litterbags and buried into the top 25cm depth of an Aridisol subjected to wind erosion. Samples were drawn at intervals of 1, 2, 4, 6, 8, 10, 12, 14, and 16 weeks and were analyzed to determine remaining dry matter weight, N, P, K, Ca, Mg, and C.
Results showed that, Neem decomposed significantly faster than both Mesquite and Mahogany with rate constant (k) of 0.44 week (Neem) and 0.12 week for both Mesquite and Mahogany. This study suggests that, Mesquite and Neem constituted readily available source of N, and they could be suitable for short-term nutrient correction. However, incorporation of residues from Mahogany caused N immobilization. With the slow decay of the latter litter, it is worthy to be used for organic matter build up in arid soils.