EFFECT OF PARTICLE SIZE OF GLIRICIDIA LEAVES AND SOIL TEXTURE ON N MINERALIZATION

Abstract

Decline in soil productivity and environmental quality in the tropics have led to a search for new methods to sustain crop production via more efficient nutrient cycling. In tropical agricultural systems with limited access to fertilizers, plant residues are often used to meet the nutrient requirements of most of the crops. In this regard, leguminous residues are an important source of N used in low input agricultural systems. The present laboratory investigation was conducted to elucidate the effect of the particle size of Gliricidia leaves (S1 ≤ 0.5 mm, S2 = 4 mm) and texture of soil (T1 = sandy clay loam, T2 = loamy sand) on N mineralization. Results revealed that the pattern and the amount of NH4 + -N released from two soil types were significantly (P ≤ 0.05) different. The highest amount of NH4 + -N (82 mg/kg soil) was released at 21st day of incubation from sandy clay loam soil treated with the particle size of 4 mm. However, in the case of NO3 - -N, loamy sand soil showed higher cumulative NO3 - -N content than that of in sandy clay loam soil. The highest amount of NO3 - - N (68 mg/kg soil) was released at 21st day of incubation from loamy sand soil treated with the particle size of ≤ 0.5 mm. Results could be concluded that nitrogen mineralization of Gliricidia leaves were affected by the texture of the soil as well as the particle size of the Gliricidia leaves. The present findings therefore stress the importance of standardizing residue particle size as it determines the rate of N mineralization in a given soil.