Decomposition and nutrient release from mixed plant litters of contrasting quality in an agroforestry parkland in the south-Sudanese zone of West Africa

We investigated under field and laboratory conditions the decomposition and nutrient release from mixed leaf litters of Faidherbia albida (Del) A. Chev. and Vitellaria paradoxa C.F. Gaertn. f. in the south-Sudanese zone of West Africa. Litterbags containing F. albida and V. paradoxa litters in varying proportions were placed on the soil surface and buried in plots receiving the following treatments: no fertilizer (control); nitrogen; phosphorus as Triple Superphosphate (TSP); and phosphorus as rock phosphate from Burkina Faso (BP). At each litterbags collection date, the undecomposed litter from each species was separated, and its remaining mass, nitrogen, phosphorus and potassium contents were determined. F. albida decomposed faster (k-values ranged from 0.060 to 0.171 week(-1)) than V. paradoxa (k-values ranged from 0.020 to 0.056 week(-1)) and released more nutrient than V. paradoxa. Mixing litters accelerated the decomposition rate of both F. albida and V. paradoxa litter. Decomposition was faster in the nitrogen and TSP plots than in the control and BP plots, and buried litter decomposed more rapidly than surface litter Also under laboratory conditions, F. albida litter decomposed more rapidly than V. paradoxa litter as the microbial specific growth rate were 0.135 h(-1) and 0.069 h(-1), respectively. Results indicated that mixing litters of contrasting qualities may be a promising option to regulating decomposition/mineralization rates from organic material.