Litter accumulation from Mucuna bracteata cover crop and its effects on some soil chemical properties in rubber plantations

Young rubber plants do not provide sufficient protection to the soil, mainly due to the poor canopy cover. Mucuna bracteata (MB) has been introduced recently as a potential cover crop for young rubber plantations. This study aimed to assess the litter accumulation from MB and its impact on soil properties under rubber. In this study sampling was done from different age groups of rubber (1 to 8 years) in two different rubber growing soil series, namely Boralu and Homagama series. Soil samples were collected under three different ground cover conditions, under MB (UM), naturals (NA) and weed free circle (WF) at two soil depths; D1 (0-15 cm) and D2 (15-30 cm). The Experimental design was a fully nested ANOVA with three replicates. Soil organic C, total sol N, available P and K were measured using standard methods. Litter accumulation of MB was significantly high in five years old plantation. Mean soil organic carbon was significantly different between two soil series and at different locations in a rubber plantation. Higher soil N contents (0.22-0.37%) were observed in four, five and six year’s old rubber plantations. Soil K content was significantly different between age of rubber plantation and at different locations in a rubber plantation. Highest soil K content (43.47mg/kg) was observed in four years old plantation and lowest value (22.92mg/kg) was observed in the one year old plantation. Available P differed significantly between different locations in a rubber plantation. Peek litter production was under four to five years old plantations and took another one to two years to achieve highest nutrient contents. Results suggest that MB improves soil fertility in 1-8 years old rubber plantations.