Dynamic of soil phosphorus fractions and its correlation with maize yield on organic acids application with phosphate rock in upland acid soil.

This research was conducted to determine the effect of organic acids (OAs) application and phosphate rock on soil P fractionation and its correlation with maize yields. This greenhouse study was carried out using a complete factorial randomized complete design with three replications. The first factor was the types of OA, consisting of citric, humic, succinic, and oxalic acids. Meanwhile, the second factor was the concentration levels of OA at 0, 25, 50, 100, and 200 ppm. The hybrid maize (Zea mays L) variety of Pioneer was used as an indicator crop, and the parameters observed were soil pH, soil P fractions (as available P, Al-P, Fe-P, reducible P (R-P), Occluded P (O-P0), Ca-P, and maize yield. Soil samples were taken seven days after planting (DAP), 14 DAP, 28 DAP, and 105 DAP. The soil P fractions were fractionated using Chang and Jackson method. The results show that, in general, OA types treatments had not significantly affected all soil P fractions, which was in contrast to OA concentration levels treatments which significantly affected soil pH and all soil P fractions, except for R-P and O-P. Increasing soil pH would increase all soil P fractions except R-P and O-P. There was a significant correlation between pH and soil P fraction with maize yield, except for R-P and O-P, with a moderate relationship. The correlation between the P fraction shows a significant to a strong relationship, except for R-P and O-P fractions were very weak. [ABSTRACT FROM AUTHOR]