ASSESSMENT OF SOIL QUALITY OF ULTISOLS UNDER RUBBER CROP ON SIMPANG EMPAT DISTRICT BANJAR REGENCY SOUTH KALIMANTAN PROVINCE

Abstract

Rubber is the most important commodity in Banjar Regency. Rubber crop is commonly cultivatedon Podsolic soils or so called Ultisols according to Soil Taxonomy. Ultisols was highly weathering soils, and consequently poor in nutrients, acidic reaction, and high toxicity of Al and Fe. To improve latex production, the government does not only expand of land but also improve soil qualities. Assessment ofsoil qualities is required to manage soil and crop more effective and efficient.The aim of the research was to assess physical and chemical soil properties under rubber vegetation in Simpang Empat District Banjar Regency South Kalimantan Province.Results of the research showed that: (1) soil physical properties were not limitation for rubber growth because there was not critical threshold for biomass productions (2) some soil chemical properties were underthe critical threshold such as pH on K1( five years rubber’s age), organic matter on K2(ten years rubber’s age), P-Braycontent, exchangeable magnesium and potasiumon K1, K2 and K3, and consequently these have not supported optimum growth of rubber yet. Base saturation on K2 < 35%, so required anyinputs to improve base saturation.