DECOMPOSITION AND NUTRIENT RELEASE FROM C-3 AND C-4 PLANT LITTERS IN A NATURAL GRASSLAND

The rate of litter loss, and the release of N, P, K, Ca during litter decomposition of two C-4 plants (Dichanthium ischaemum L. and Chrysopo gon gryllus L.) and one C-3 plant (Festuca ovina H.) were studied for 24 months. This was achieved by placing leaf and culm litter in nylon screen bags close to the soil surface, sampling every three months to mease the changes in litter weight and chemical composition during the experimental period. Litter decomposition was faster during the first 12 months for both leaves and culms of all species. The order was D. ischaemum > F. ovina > C. gryllus. The mean rate litter loss for the 1 2 and 24 month period was similar for leaf and culm litter. Nitrogen a ccumulation was observed during the entire experimental period for all species. Phosphorus release had occurred during the experimental peri od in the decreasing order: C. gryllus > D. ischaemum > F. ovina. Pota ssium release was observed after 12 and 24 months in the decreasing or der D. ischaemum > C. gryllus > F. ovina, while calcium was accumulati ng. The decomposition rates were similar for C-4 and C-3 plants and th eir contribution to nutrient cycling depended on the release of the va rious elements during decomposition. (C) Elsevier, Paris.