Biodegradation of low molecular weight organic acids in rhizosphere soils from a tropical montane rain forest

► Biodegradation of oxalate and citrate in the rhizosphere soil was studied in tropical rain forests. ► In P-deficient podzolic soil, rhizosphere soil solution contained higher concentrations of organic acids than the bulk soil. ► The biodegradation rates of organic acids were higher in the rhizosphere than the bulk soil. ► The higher levels of organic acids in the rhizosphere of P-deficient soil were caused by greater root exudation.