Nutrient content of bulk precipitation in south-central Java, Indonesia

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Abstract
The chemical composition of bulk precipitation was studied for a period totalling 18 months between 1975 and 1978 at a high rainfall site in central Java. The following elements were determined: calcium, magnesium, sodium, potassium, nitrate-nitrogen, chlorine, phosphate-phosphorus, silicon, aluminium, iron, manganese and pH. Ammoniacal nitrogen, total nitrogen and sulphate-sulphur were determined, during four weeks in May 1983. Concentrations of all elements rose dramatically during the exceptionally severe dry season of 1977 which may have caused accession rates for some nutrients to be overestimated (i.e. compared to a year with ‘normal’ rainfall) by about 10%. Results are explained in terms of prevailing wind directions and proximity to, or absence of, particular solute sources, such as the ocean, volcanoes or eroding lands.Most elements exhibited intermediate concentrations when compared with data for other humid tropical locations; sodium and perhaps nitrogen were on the low side and pH on the high side of the spectrum. Annual accession rates at the study site were considerable by pan-tropical standards, mainly as a result of high rainfall totals. Comparing accession rates with 25-year-average nutrient immobilization rates in stemwood of local plantations of Pinus merkusii Jungh. et de Vr. and Agathis dammara Warb. showed atmospheric inputs of magnesium and potassium to be high enough (theoretically) to account for losses of these elements in stemwood removal. Corresponding figures for nitrogen were 90% (Pinus) and 50% (Agathis), and for calcium and phosphorus 60 and 40% respectively (both species).