The Effect of Phosphate Rocks on Spring Barley Shoot Yield in a Pot Trial

Summary Depending on their origin, sedimentary phosphate rocks (PRs) may differ in their P solubility, and, as a consequence, in their agronomic effectiveness. The ef-fect of six phosphate rocks (PR) – originating from Algeria (ALG), North Florida (FLO), North Carolina (NCA), Senegal (SEN) Morocco (MOR) and Hyperphos-phate (HYP) with various P solubility (evaluated by 2% formic acid, 2% citric acid, and neutral ammonium citrate) – as well as single superphosphate (SSP) and superphosphate + lime (SSP + Ca) (each P source on 4 P levels, with doses of 0, 100, 400 and 1600 mg P 2 O 5 ·kg -1 soil) on the shoot yield of tillering stage spring barley, soil available P (i.e. H 2 O, Olsen, Bray1, Lakanen-Ervio (LE) and ammonium lactate (AL) extractable P contents) were studied in pot experiments set up with acidic sandy soil (Nyirlugos, Hungary) and acidic clay loam soil (Ragaly, Hungary), both with low P supplies. The average spring barley shoot yield at the beginning of shooting was 95% higher on the colloid-rich acidic (pH