Phosphorus availability in a low pH highly weathered soil as affected by added salts

Abstract

Concentration and identity of cations and anions in the soil solution may affect soil P reactions and thus P availability. The magnitude of these reactions was evaluated in this research after application of various salts to a highly weathered low pH soil. Chloride, nitrate, and sulfate salts of Na, NH4, K, Ca, Mg, Sr, or Cu were added to the soil after addition of 360mg P/kg trying to simulate ion concentrations around granules of fertilizers in the soil. Thirty days later, P was determined in the soil solution (Pli) and on the solid phase (Psi). The soil samples of some treatments were leached with water and three days later a new soil solution was displaced. Separate addition of all salts increased Pli, except NaCl at the lowest rate. The increase of Pli was highly associatcd with amount of native cations displaced to the soil solution by the applied salts. Salt solubility, concentration, and sometimes identity of cation and anion also influenced Pli. Some salts decreased Psi, but this was not correlated with any soil property measured. The effects caused by salts on Pli and Psi disappeared after leaching the soil samples.

Minjingu phosphate rock availability in low-pH highly weathered soil as affected by added salts

“…Thus, the accessibility of the adsorbing surface to phosphorus in solution should be greater with divalent (Ca 2+ ) than with monovalent (Na + ) cations in the exchange complex. Ernani and Barber (1995) have also shown that in the presence of different cations the magnitude of P in solution followed the descending order; Na…”