ABSTRACT

Five experiments: leaf litter production, leaf litter decomposition, quantity of precipitation pathways, nutrient cycling of leaf litter and of precipitation pathways, and maize production were conducted in 2016 and 2017 in Diospyros crassflora plantation in the Humid Forest Research Station, Forestry Research Institute of Nigeria (FRIN), Okwuta-Ibeku, Umuahia, Abia State, Nigeria. A randomised complete block design (RCBD) was used to study the leaf lifterfall of Diospyros crassUlora in the D. crassiflora plantation. A 2 x 6 and a 2 x 7 factorial experiment each in RCBD were also conducted in 2016 and 2017 respectively to study the biweekly decomposition rates of D. crass fiora in the nursery unit of FRIN. A 3 x 9 x 2 factorial experiment in RCBD was also used to study the quantity of water and nutrient cycling contents of three precipitation pathways overtime in the D. crassfiora plantation. A 3 x 3 factorial experiment in RCBD was used to determine the effect of organic and inorganic fertilizer rates on the growth and yield of Zea mays in a 4 and 5 years old D. crassifiora plantation in 2016 and in 2017, respectively. Result showed that, the dry season months of November- March had leaf litter production of 11.58 —7.48 kg ha' in 2016 and 22.70 -16.10 kg ha' in 2017 which were significantly higher than the rainy season months of April-October of 1.98 - 6.03 kg ha' in 2016 and 4.80 - 13.00 kg ha 1in 2017. Total leaf litter decomposition (100%) rates of soil surface-placed and soil-incorporated modes were obtained at the 12thand 14th weeks after leaf litter placement in 2016 and 2017 respectively. The results of nutrient contents in the leaf litters in 2016 and 2017 were statistically similar for both macro and micro-elements (N, P, K, Ca, Na, Mg, Fe, Org. M., Org. C, pH and Pb). In terms of the precipitation pathways stemflow and rainfall had significantly the highest and the least water quantities, respectively. Stemflow pathway in 2016 and 2017 had the highest (p 0.05) nutrient concentrations of calcium (Ca), potassium (K), magnesium (Mg), chlorine (Cl), iron (Fe), lead (Pb) and tetraphosphate. Application of inorganic (NPK 15:15:15) and organic (poultry manure) fertilizer at 0.00kg, 250.00kg, 500.00kg and 0.00t, 2.00t and 4.Oot rates in 2016 and 2017 improved and increased the growth attributes of maize in D. crassifiora plantation. The results of the various rates of fertilizer (F), poultry manure (P) and the fertilizers x poultry manure treatment combinations were not significantly different from each other within the period of study in terms of maize yield attributes. In conclusion, agriculturists, environmentalists and foresters are encouraged to adopt D. crassflora species in their farming system and plantation establishment because of its values in mineral nutrients. The leaf litter of D. crassiflora should be utilized as one of the main sources of organic manure due to its fast rate of decomposition and consequently its high mineral contents that could be deposited in the soil.