Structural diversity, leaf litter recycling and allelopathic influences of leaf litter in an agroforestry homegarden of southern Kerala

Agroforestry systems offer immense potential for sustainable agriculture as the tree-based systems are rich in biodiversity and organic matter production that can be suitably recycled in the systems. The present study explored the diversity of a selected tropical agroforestry homegarden in southern Kerala. It assessed the organic additions via litter fall from the perennial components, recycling through vermicomposting and allelopathic influence of litter on sprouting and early growth of tannia (Xanthosoma sagittifolium). The homegarden represented a multispecies cropping system with diversity index of 2.03 and annual litter additions of 1782.89 kg from the 28 perennial tree components. The amount of litter added by the different trees varied with the species, number and age. Recycling of the litter using earthworms was attempted and vermicomposting of litter could accrue nutrients to the tune of 10.67 kg N, 3.82 kg P and 1.71 kg K per year in the homegarden emphasizing the importance litter has on sustaining soil productivity. The allelopathic influence of selected eight species litter revealed that litter leachates at 2 per cent did not exert any significant allelopathic effects but when applied as mulch, mango, nutmeg and Ailanthus litter exhibited significant allelopathy on sprouting and seedling growth of tannia.