Karakterisasi Erapan Nitrat pada Tanah Pertanian Lahan Kering di Pulau Jawa.

Abstract

The urea fertilizer and manures were used excessively by farmers. It caused the accumulation of nitrate in Agriculture soils. The knowledge of soil capability to sorb nitrate is very important concerning the nitrate movement in soil profile. The objectives of this research were to (1) Characterization of physico-chemical properties of upland soils in Java island, (2) Finding the best equation to simulate nitrate sorption on upland soils in Java island, and (3) Correlation between physico-chemical properties and parameters of nitrate sorption. Prior to nitrate sorption, the soil was saturated with chloride ion. Afer that, the 2.00 g of soil was equilibrated in 5 ml solution containing 0.005 to 0.2 mol L-1 of KNO3. After equilibrium was reached, nitrate was determined by UV Spectrophotometer with wave length 210 nm and then was corrected with 275 nm for dissolve organic carbon (C). The nitrate sorption data were simulated with Langmuir, Temkin and Freundlich equation. The results showed that the Freundlich equation simulated nitrate sorption better than Langmuir and Temkin. The R2 of equation of Freundlich ranged from 0.87 to 0.99. The nitrate sorption maxima (K) of Freundlich were positively correlated with total C (r=0.27), oxalate-extractable aluminum (Alo) (r=0.41), oxalate-extractable iron (Feo) (r=0.16), dithionite-citrate-bicarbonate-extractable aluminum (Ald) (r=0.34), dithionite-citrate-bicarbonate-extractable iron (Fed) (r=0.01) and Alo + ½ Feo (r=0.42). The K values were negatively correlated with clay content (r=-0.19). As for n values of Freundlich equation, it was positively correlated with total C (r=0.11).