Abstract

Phosphate rock (PR) and triple superphosphate (TSP) are options for phosphorus (P) fertilization of crop and pasture production systems. However, to our knowledge, no studies have compared P sources with different solubilities in field trials to date. The aim of this study was to compare the effect of PR and TSP on forage yield, P uptake and nutritive quality of pastures growing in Andisols. Three experiments were conducted in southern Chile, analysing the factorial combination of two P sources (PR and TSP) and four P rates (0–328 kg P ha−1). Results showed that cumulative dry matter production in year 1, year 2 and total was significantly (p ≤ 0.05) affected by P dose, time of cut and the interaction of both variables, indicating that PR is as effective as TSP in acid soils. The treatments did not show significant differences among themselves (p ≥ 0.05) in foliar P concentration, P uptake, P apparent recovery efficiency and nutritive quality of pastures evaluated. The highest P apparent recovery efficiency was obtained with 22 kg P ha−1 and 44 kg P ha−1 independent of the phosphate fertilizer applied. A P demand factor of 2.7–3.1 kg P Mg−1 dry matter was estimated. All these information will be useful to improve P fertilization managements of pastures growing in Andisols.