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Title: Decomposition and nutrient release patterns of leaf mulches of Leucaena leucocephala, Gliricidia sepium and Cassia spectabilis
Authors: Takyi, Sraha
Issue Date: 25-Sep-1994
Series/Report no.: 2030;
Abstract: The rate of decomposition and nutrient release patterns of leaf mulches of Leucaena leucocephala, Gliricidia sepium and Cassia spectab1is were investigated under field conditions using wooden square frames over a period of 70 days. The experimental design used was a complete randomized design with three replications using the tree species as treatments. Fresh leaf mulch weighing the equivalent of 100g dry weight of the species were spread in the wooden frames, sampled every two weeks and the dry weights and the concentration of C, N, P, K, Ca and Mg determined. Soil under the wooden frames were also sampled at 10-15cm and 15-30cm profile depths every two weeks and analyzed for C, N, P. K, Ca and Mg. The initial chemical characteristics of the leaf mulches were also determined. Decomposition rates of the leaf mulches differed significantly (P < 0.05) and followed the order: Leucaena leucocephala > Gliricidia sepium > Cassia spectabilis. The half-life values were; 18 days for L. leucocephala, 35 days for G. sepium and 69 days for C. spectabilis Initial concentrations of nutrients and percent lignin in leaf mulch of the species varied significantly (P < 0.05). Gliricidia sepium had the highest concentration of Phosphorus (0.45%), Potassium (2.87%), Calcium (1.40%) and Magnesium (0.44%). Leucaena leucocephala had the highest Nitrogen (3.85%) and Carbon (46.20%). Percent lignin was 5.6 in L. leucocephala, 7.6 in G. sepiu.m and 8.7 in C. spectabilis. Generally, Potassium showed the highest release rate with nutrient release constant (K) ranging between 0.018 in C. spectabilis and 0.045 in G. sepium. The release of the nutrients from the leaf mulch was ranked as follows: K > Mg > N > P > C > Ca for L. leucocephala, K > Mg > P > N = Ca > C for G. sepium and K > Mg > P > N > Ca = C for C. spectabilis. The chemical characteristics of the mulch material especially percent nitrogen and lignin played key roles in determining the rate of decomposition and nutrient release. Soil nutrient levels improved significantly under the decomposing leaves at both 0-15cm and 15-30cm profile depths: The general order of improvement in soil nutrient content at 0-15cm depth of profile was N > K > Mg > Ca > C > P for L. leucocephala and G. sepium and N > K > Mg > C > Ca > P for C. spectabilis. At the 15-30cm depth the trend was N > K > Mg > Ca > P > C for the three species.
Description: A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirement for the award of the Degree of Master of Science in Agroforestry, 1994
URI: http://hdl.handle.net/123456789/3300
Appears in Collections:College of Agric and Natural Resources

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