KAJIAN KANDUNGAN MINERAL ALOFAN DAN FENOMENA FIKSASI FOSFOR PADA ANDISOLS

Abstract

ABSTRACT
Research on the allophane content on Andisols and phosphorus fixation phenomenon has been conducted in Kerinci District. The existence of Allophane in the soil is inversely proportional to the availability of nutrients, particularly phosphorus, nitrogen, sulfur, and Chlor. All these elements were fixed by clay minerals alofan, in case this element is needed crops.This study aims to: (1) know the level of allophane content in Andisols of Kerinci District, (2) study the phenomenon of fixation of phosphorus in Andisols. This research was conducted using survey method. Determination of the profile and soil sampling conducted at the unit block of land that is set according to landform. Soil samples were taken at depths of 0 -30 cm and 30-60 cm. Soil characteristics were observed Determination of Al, Fe, and Si-amorphous with oxalic acid extraction, amorphous Fe and Al-Na pyrophosphate extraction, C-organic, H and Al-exchangeable, phosphorus retention, pH H2O, pH KCl 1 N , and pH with 5% NaF, Determination of P-available, P-Total, and Determination of K, Ca, Mg, NH4, and NO3 is available. The results showed the amount of allophane content more widely available in 30-60 cm layer (35,20%) with 97.8% phosphorus retention capacity, while in the layer 0-30 cm, there are number of allophane (21,46%) with phosphorus retention capacity 97,7%. P content classified as moderate to high total amount in soils (1.533,33 ppm in a layer of 30-60 cm up to 3.400 ppm in the layer 0-30 cm). Of the total P content in the soil that retention by alofan, soil was still able to provide P-available amount (4,63 ppm in a layer of 30-60 cm to 4,.76 ppm in the layer 0-30 cm).