Dissolution of Phosphorus Fertilizers of Differing Solubility in Peat Soil: a Field Experiment on a Drained Pine Bog
A 2-yr field trial was conducted on a drained pine bog to measure the dissolution of five phosphorus (P) fertilizers of differing solubility. The rate of fertilizer dissolution was measured using a sequential fractionation which involved pre-extraction with 0.5 M NaCl/TEA followed by 1 M NaOH and a mixed acid (HNO3 + HCl + H2SO4) digestion. About 56% of Siilinjärvi apatite, a hard magmatic rock phosphate, dissolved over the 2 yrs. For a commercial P + K fertilizer manufactured from Siilinjärvi apatite and KCl (water-soluble P < 0.1%), the corresponding value was 44%. For Moroccan phosphate rock, and a commercial fertilizer manufactured from Moroccan phosphate rock and KCl (water-soluble P = 15.8%), the dissolution was about 44% and 58%, respectively. For superphosphate (water-soluble P = 79%), the corresponding value was 93%.