Rates of Decomposition and Nutrient Release from Biomass of Various Species of Tropical Legume Cover Crops in Dryland Soils of Eastern Indonesia

Abstract

The contribution of various species of tropical legume cover crops used in the dryland tropics of Indonesia to increase organic matter and plant nutrients in the soils is generally unknown. A pot experiment arranged in the field were conducted to study the rates of decomposition and nutrient release from these cover crops. The factorial experiment was designed as a randomized complete block with two treatment factors and three replications. The first factor was species of legume cover crops viz. Centrosema pubescens L., Mucuna pruriens L., Crotalaria usaramoensis L., and Phaseolus lunatus L., and the second factor was methods of placement of biomass (in litter bags) either placed on the soil surface or embedded in the soils. The rates of decomposition and nutrient release were higher in biomass embedded in the soils which were 0.303 (2.76 year^-1), 0.264 (2.41 year^-1), 0.187 (1.71 year^-1) and 0.104 (0.95 year^-1) for C. usaramoensis L., P. lunatus L., M. pruriens L. and C. pubescens L., respectively. Nutrient release (N, P, K, Ca) from C. usaramoensis L. and P. lunatus L.embedded in the soils reached a half time (more than 50%) of 20 days while those from M. pruriens L. and C. pubescens L. did that of 30 days. Crotolaria usaramoensis and Phaseolus lunatus had the high, Mucuna pruriens had  the medium and Centrosema pubescens had the low biomass quality. It was concluded that the use of C. usaramoensis L. and P. lunatus L. embedded in the soil 10-20 days before planting, will be the apropriate methods to amend soil properties in the dryland tropics.

Keywords: Legume cover crops biomass, The rates of decomposition and nutrient release