Abstract:
Use of biomass fertilizers appears to be the most appropriate way of adding nutrients into the
soil which is environmental friendly and suitable for local conditions. Among the biomass
fertilizer sources, Gliricidia has been identified as the most suitable nitrogen fixing legume.
Some experiments that have been carried out showed that the Gliricidia with high N content
and low lignin level is more suitable as N source. An investigation carried out to determine
the nitrogen (N), phosphorous (P), and potassium (K) contents of different parts of gliricidia
plant and to develop a slow-release nitrogen biomass fertilizer systems using gliricidia plant.
Four types of gliricidia plants (Provenance Trail Series of Gliricidiasepium 17/84 Oxford
Forestry Institute (OFI), Gliricidiasepium 25/84 OFI, Gliricidiasepium 25/84 OFI and
Gliricidiasepium (Local species)) were obtained from Rathmalagara estate, Madampe in
Coconut Research Institute (CRI) in Sri Lanka.
According to the experimental results the level of nitrogen in different parts of the gliricidia
plants varied from 27860 mg kg-1to 5222 mg kg-1. It was found that phosphorous and
potassium content in gliricidia plant varied from 892.2 mg kg-1 to 1258.2 mg kg-1 and from
208.6 mg kg-1 to 8678.5 mg kg-1 respectively. Biofertilizers were prepared from gliricidia
bark chips after treated with a saturated solution of urea (CH4N2O). The morphology and
physiochemical parameters of treated gliricidia bark chips were investigated. Experimental
result indicated that after gliricidia bark chips were treated with urea, total nitrogen content in
the bark increased by more than 200% giving the value as 36700 mg kg-1.The initial nitrogen
content in the bark was 17878 mg kg-1. This study also evaluated the release pattern of
nitrogen from impregnated gliricidia wood chips in a soil matrix and found that nitrogen was
released in a slow-release pattern. The above findings confirm and gave promising results to
further develop urea incorporated gliricidia bark particles as a slow-release new biomass
fertilizer system.
