The availability of soil phosphate. I.—Examination of the soil solution with special reference to the fixation of phosphate

Abstract

The effects of fertilizer treatments and of season on the constituents of the soil solution, with special reference t o phosphate, have been examined, using soils tested as part of a long-term fertilizer-experiment.The concentration of inorganic phosphate in the soil solution in phosphate-treated plots was higher than that of the control throughout the year, the increases ranging from 21.5 to 66.604. The effect of superphosphate did not increase during cropping ; the concentrations of inorganic phosphate in the soil solution were low in summer and varied very little through the year. Ammonium sulphate and lime reduced the inorganic-phosphate concentration. I n plots receiving dung the concentrations of inorganic phosphate were unusually high, the increases ranging from 120 to 635% in the o-%in. soil layer.