Abstract

This study aims at elucidating the combined effects of humic compounds and phosphate-solubilizing bacteria (Pseudomonas putida) to improve characteristics of ultisol and to increase the yields of soybean conducted in a glasshouse. The humic compounds are extracted from rice-straw compost, the phosphate-solubilizing bacteria obtained from Bogor Agricultural University, and the soil (Typic paleudult) collected from Kentrong Banten, Indonesia. The results have shown that application of humic compounds combined with inoculation of phosphate-solubilizing bacteria increases pH and available P, and decreases exchangeable Al of an ultisol. The improved soil characteristic, however, does not lead to the significant differences in the uptake of macronutrients by plant.

Key words: Acid soil, exchangeable aluminium, humic compounds, Pseudomonas putida, soybean.