Comparing Throughfall and Litterfall Nutrient Fluxes in a Rubber (Hevea brasiliensis willd. muell-arg) Plantation Agro-ecosystem at Ikenne, South-west Nigeria

Abstract

This study compares nutrient fluxes (throughfall and litterfall) in a rubber (Hevea brasiliensisWilld. Muell-Arg) plantation agro-ecosystem at Ikenne, SW Nigeria. Throughfallsamples were collected bi-weekly under the rubber canopies (40-, 15-, and 5-year-old) using throughfall funnel collectors with 10 replicates. Litterfall was collected on a monthly basis in the three rubber stands using twenty-four 0.25 m2litter traps (eight replicates in each of the three rubber stands) positioned randomly to estimate total annual litter production (dry biomass)and its main fractions. Throughfall and litterfall samples were analyzed for total nitrogen, sodium, phosphorus, calcium, potassium and magnesium. The annual means of throughfall in the different stands were compared by solution type using one-way analysis of variance (ANOVA), followed by a post-hoc separation of means by the Scheffe-test (p<0.05).The litterfall data were analyzed using one-way analysis of variance based on the representative of 12 months. The results revealed a clear pattern of increased levels of base cations and fluxesof throughfall compared to those occurring in precipitation. Fluxes of Ca2+in throughfallare typically 1.5-2 times greater than those occurring in rainfall. Among the rubber stands, fluxes of K+are also greater in throughfall, consistent with previous studies. The enrichment of elements in throughfallhas been ascribed to the dissolution andwashout of atmospheric materials deposited on the canopy.Comparison of total annual litterfall nutrient budgets show that the 15-year-old rubber stand was cycling more Mg2+, N, Na+, K+, P, and Ca2+in litterfall than the 40-and 5-year-old rubber stands.