Phosphorus transformation in acid soil as influenced by humic substance

The purpose of the study was to assess the influence of humic substance on the transformation of phosphorus in acid soil, so an experiment was conducted in a lab setting using the same soil (Typic Rhodustalf) collected from the land where the field experiment is expected (Agricultural and Horticultural Research Station, Tarikere taluk, Karnataka India). Humic substance employed in treatment application was extracted from farm yard manure. The study proven that, in contrast to P fertilizers applied without humic substance, application of humic substance at higher doses along with P fertilizers increased the available P status, saloid-P and organic-P fraction over the course of the incubation period, particularly when rock phosphate combined with humic substance @ 60 mg kg−1. However, compared to P fertilizers without humic substance treatments, significant decrease in in Al-P, Fe-P, reductant soluble P, occluded P and Ca-P was found in Rock phosphate + humic substance @ 60 mg kg−1 with lower P fixation (35.31%) and Rock phosphate + humic substance @ 40 mg kg−1 with P fixation of 37.32%, while the absolute control treatment (60.34%) had the maximum P fixation capacity.