Csathó Péter

In a pot experiment five phosphate rocks, originated from Algeria, Florida, North Carolina, Senegal and Morocco, Hyperphosphate and single superphosphate (SSP), as well as SSP+CaCO3 were applied in 0-100-400-1600 mg P2O5 kg-1 rates, with particle size of <160µm, on a strongly acidic sandy soil with very low available P content. Red clover plants were grown in the pots in greenhouse conditions. Shoot and root growth, P uptake and P acquisition efficiency were strongly depressed by the increasing rate of applied P fertilizers above a critical rate, which was around 100 mg P2O5 kg-1 of soil for red clover for the phosphate rocks and soil conditions of the experiment. Both the type of applied P fertilizer and its rate of application markedly affected the P acquisition efficiency of the red clover crops. Senegal treatment gave the lowest plant phosphorus uptake and the highest Cd uptake, which was more than three times higher, than Cd uptake from any other P source. The bioavailability of Cd increased with increasing P rates, except of the more buffered SSP+CaCO3 treatment.

The effect of phosphate rocks with various P-solubility on P bioavailability, root growth and P uptake of spring barley crops were studied on an acidic sandy soil in different experimental conditions ans by dynamic simulation. Root length and P influx varied significantly influenced by the P and CaCO3 content and reactivity of the P sources. Phosphate rock (PR) treatments enhanced root growth. The simulation results demonstrated the contribution of root hair formation and P mobilization by rhizosphere acidification in the increased acquisition efficiency of barley in PR treated soil.

Árendás, T. és Németh, T. 2005. (1.1.)