Litter dynamics of six multipurpose trees in a homegarden in Southern Kerala, India.
Isaac S. R., Nair M. A.
Author Affiliation: Krishi Vigyan Kendra, Sadanandapuram, Kottarakkara, Kollam 691 550, Kerala, India.
Agroforestry Systems 67 : 203-213
Abstract : Multipurpose trees, the integral components of homegardens, contribute significantly to the closed nutrient cycling processes and sustainability of the ecosystem. Although, the litter production and probable nutrient returns via litter in homegardens have been documented, quantification and characterization of the decomposition and bioelement release from the litter have received relatively little scientific attention. The objective of the present study is to explore the litter dynamics of 6 locally important multipurpose trees (Mangifera indica, Artocarpus heterophyllus, Anacardium occidentale, Ailanthus triphysa, Artocarpus hirsutus and Swietenia macrophylla) in an agroforestry homegarden in Southern Kerala, India. Litterfall and nutrient additions in the 6 species ranged from 383 to 868 g m-2 year-1, and 6.4-8.8, 0.17-0.42 and 1.1-2.8 g m-2 year-1 for N, P and K, respectively. The annual litter output in the homegarden was 425 kg with A. hirsutus, M. indica, A. heterophyllus and A. occidentale recording significantly higher litter and nutrient additions. Leaf litter decay studies revealed A. heterophyllus and A. occidentale to be the most labile litter species and S. macrophylla the most recalcitrant. The decay rate coefficients varied significantly among the species. Foliage decomposition rates related to the initial chemical composition of the litter revealed best correlation with lignin. NPK release was almost complete by the end of decay in all species inspite of the initial phases of accumulation observed for N and P. Two-way analysis of variance test revealed significant differences in the contents of the 3 elements as a function of species and time elapsed. Macronutrients were released in the order K > N/P. The higher rates of decay and nutrient turnover in M. indica, A. heterophyllus and A. occidentale foliage indicated the potential of using these species' litter as nutrient inputs in agriculture while A. triphysa, A. hirsutus and S. macrophylla performed better as organic mulches taking a longer time for decay and hence nutrient release.