Abstract:
Litterfall and subsequent decomposition is a fundamental process underlying the input of nutrients
to the soil in terrestrial ecosystems. The aim of this study was to investigate soil nutrients, root
growth, litterfall and potential nutrient return to soil in three diverse agroforestry systems; home
gardens(Mangifera indica, Artocarpus heterophyllous, Coffea spp.) gliricidia-coffee mixed plantation,
and teak monoculture plantations. The study was conducted at the University of Peradeniya
Experimental Station at Dodangolla during September-December 2022. Litter samples were
collected into 2 m × 2 m litter traps, which were established 1 m above the ground in each
agroforestry system. Initial soil samples were collected at 1 m distance away from the downside of
litter traps at two soil depths (0-15 cm and 15-30 cm). Ingrowth cores (15 cm diameter and 30 cm
depth) were inserted at 1 m distance from the litter traps and roots grown in to the cores were
sampled after 4 months. The amount of litterfall, nitrogen (N), phosphorus (P), and potassium (K)
contents in the litter and soil samples, and root growth into ingrowth cores were measured. Soil
nutrient contents did not change significantly across agroforestry systems, except the higher P
contents in the samples from home gardens (0-15 cm depth) than those from others. The highest
total litterfall was recorded in teak plantation (823 g/4m²±107.8) followed by home gardens (748
g/4m²±111.8) and gliricidia-coffee mixed plantation (536 g/4m²±30.77). The greatest root growth
was observed in gliricidia-coffee plantation, while home gardens showed the lowest. Gliricidia-coffee
plantation produced litters with the highest N(6015.61mg±428.9) contents and return of N through
litterfall was also the highest, while home gardens and teak plantation had the highest K(875.29mg
±62.83,1591.74mg±106.95) and P(3409.44mg±357.17,2494.46mg±173.59) return respectively.
Species composition could determine the type and the amount of nutrient return to the soil through
litterfall.
