Availability of Phosphate Carriers to Small Grains and Subsequent Clover in Relation To: I. Nature of Soil and Method of Placement¹

Synopsis Comparative effectiveness of phosphate carriers as shown in yield and uptake with small grains was found to be as follows: ammonium phosphate ⋜ concentrated superphosphate ⋜ ordinary and ammoniated superphosphate, metaphosphate and high water solubility nitric phosphate > Rhenanian, low water solubility nitric and fused tricalcium phosphates > rock phosphate. Fertilizer nitrogen and effective placement were prime factors in promoting efficient utilization of phosphorus carriers. Phosphate availability to clover following oats was similar irrespective of carrier and placement method.