Sulphate, Chloride and Nitrogen Compound Concentration in Atmospheric Deposition and Effects on Nutrient Cycling in a Rubber Plantation Agroecosystem at Ikenne, SW Nigeria

摘要

Bulk precipitation, throughfall and stemflow solution chemistry beneath rubber (Hevea brasiliensis Willd) Muell-Arg. Euphorbiaecae plantation agroecosystem at Ikenne, SW Nigeria, was measured. Throughfall and stemflow chemistry from event-based sampling of 3 different age stands was compared with the chemistry of incident precipitation. Throughfall pH in 5 year old rubber (5.92), 15 year old (5.83) and 40 year old (5.70) canopies, respectively. These values were was significantly more acidic than gross precipitation (6.20). Stemflow pH ranged from 5.7 (5-year-old) to 6.0 (15-year-old). During the study period only Cl was significantly higher flux under the forest canopy relative to precipitation. About 50% of the inorganic nitrogen in precipitation was taken up by the canopy and there were significant differences in throughfall and stemflow chemistry among the 3 stands, perhaps due to differences in smoothness of the stem. Seasonal differences were important, with highest deposition in wet season. Multiple regression analysis of the throughfall patterns showed significant correlations of throughfall chemistry with the length of the antecedent dry period and rainfall quantity for all elements examined.