PHOSPHORUS MOVEMENT IN SOME CALCAREOUS AND NONCALCAREOUS MANITOBA SOILS

Abstract

The extent of movement of phosphorus from the application site of P-32 labelled monoammonium phosphate and diammonium phosphate pellets was investigated. The rate of movement of phosphorus from a monoammonium phosphate pellet was also studied. The extent of phosphorus movement from a monoamnionium phosphate pellet was greater than that from a diammonium phosphate pellet. This observation was more noticeable in the calcareous soils than in the noncalcareous soils. The extent of phosphorus movement was greater in noncalcareous soils than in calcareous soils for both sources of phosphorus when added as a pellet. The rate of movement of phosphorus was also more rapid in noncalcareous soils than in calcareous soils.It is most likely that the high pH and large amounts of calcium and magnesium found in the soil solutions of the calcareous soils resulted in a rapid precipitation of the added phosphorus very close to the pellet site. Thus, the rate and extent of phosphorus movement in the calcareous soils was restricted more than in the noncalcareous soils, which had a lower pH and contained smaller amounts of calcium and magnesium in the soil solution.