ABSTRACT

 Litter production and nutrient cycling in an Irvingia wombulu- based agroforestry March, the early rainy season, months of April and May and the late rainy season, month of October gave significantly higher leaf litterfall than the mid-rainy season months of June - September. There were no significant differences between the mean monthly twig litterfall. Leaf and twig litterfall accounted for 80.9% (9.17 t ha1) and 19.1% (2.16t ha’1) litterfall respectively. The overall mean monthly concentrations (%) of elements in the leaf and twig litters were as follows: (a) Leaf litter: N : 1.31; P : 0.52; K 0.27; Na : 0.03; Ca : 1 .94; Mg : 0.93; organic C : 43.51; C : N ratio : 33.34 (b) twig litter : N : 0.69: P : 0.03; K - 0.35; Na - 0.04; Ca - 1.42; Mg - 0.73; organic C : 50.51: C : N ratio -78.99. The mean annual inputs (kg ha'1) of nutrient elements to the soil from leaf and twig litterfall were in the following significant order (a) leafLitterfall: organic C (4,060.57) Ca (165.74) N (123.33) Mg (85.03) P (46.87) K (25.10) Na (2.51); (b) twig litterfall: organic C (1096.04) > Ca (27 .09) > Mg (18 . 21)>N (13.14) > K (8.27) > P (5 .25) Na (0 . 75). The 9,h - 39lh weeks after leaf litter placement (w.a.Lp) gave w.a.I.p in the surface - placed (56.7 - 67.3%) and soil incorporated (30.7 - 50.7%) techniques. No significant differences existed between the mean results of the two l-\ 1/ r techniques. Leaf litter half-lives of the surface - placed and soil incorporated methods significantly higher leaf litter decomposition rates in the surface - placed (84.3 - 97.2%) and soil incorporated (72.5 - 99.2%) leaf litter decomposition methods than the 3rd - 6th ecosystem was studied for 12 months (April, 1999- March, 2000) at the Forestry Research Institute of Nigeria, Umuahia, Nigeria.