Agronomic Effectiveness of Bayovar Phosphate Rock in Soil with Induced Phosphorus Retention

A greenhouse experiment was conducted with soil from the A horizon of an acid Mountview silt loam (Typic Paleudult) to measure the relative influence of soil P retention capacity on P availability from Bayovar (also known as Sechura) phosphate rock (Peru) with that from triple superphosphate (TSP). The P retention capacity of the soil was adjusted by application of variable quantities of freshly prepared amorphous Fe gel. The P sources were incorporated into the treated soil at rates to supply 0, 150, and 300 mg total P kg −1 soil. Corn ( Zea mays L.) was grown as a test crop. The Fe gel treatments significantly increased the P retention capacity of the soil and resulted in significant reductions of both dry matter production and P uptake with both P sources. The effectiveness of the phosphate rock, however, tended to decline to a greater extent than that of TSP with increasing P retention capacity. These results suggest that, contrary to popular opinion, the effectiveness of phosphate rock relative to soluble P fertilizer may be less on soils with high P retention capacity than on soils with the same pH but with lower P retention capacity for short‐term crops such as corn.