Nutrient Inputs via Stem Flow in a Rubber - Hevea brasiliensis Wild Muell-Arg. Euphorbiaecae - Agro-ecosystem Plantation at Ikenne, Southwest, Nigeria

Abstract

Nutrients via stem flow are important in tropical agro ecosystems that receive little or no external sources of essential nutrients.  This study compares stem flow of three age stands (40, 15, and 5 year-old) of rubber (Hevea brasiliensis) in Ikenne, South west, Nigeria.  Stem flow solutions were collected with stem flow collars spiralled round eight selected trees in a 0.1ha (50m x 20m) experimental plot established in each of the three rubber stands.  Collected data were analysed statistically using one-way analysis of variance (ANOVA); and the student t- test to assess the significant differences (P < 0.05).  Total nutrient returns via stem flow for the 15-year-old stand were 28.39, 4.49, 38.9, and 3.54 kg ha^-1 year ^-1 for Ca²⁺, Mg²⁺, K⁺ and Na⁺ respectively compared to 22.7, 3.64, 36.3, and 3.17 kg ha^-1 year ^-1 for Ca²⁺, Mg²⁺, K⁺ and Na⁺ respectively, in the 40-year-old stand.  Except for Cl^-, anions were greatly reduced suggesting nutrient uptake and less pollution.  High amount of Ca²⁺ also suggest the contribution of dry deposition of local origin to the leached metabolites.  The 15-year-old stand appears to have more efficient nutrient return compared to the younger 5-year-old stand on one hand and the older 40-year-old stand on the other.  There is the need for augmented nutrients in the plantation by adding fertilizers in quantities that will not alter nutrient cycles and at the same time ensure sustainable and productive agro-ecosystem.