EFFECT OF CERTAIN CATIONS AND ANIONS ON PHOSPHORUS AVAILABILITY

Abstract

In an attempt to gain some basic information on the fixation and availability of P as affected by the presence of different amts. and kinds of salts on a particular soil. Soil was obtained from the field station at Lewiston and 3 levels of 9 different salts added to give 27 salt treatments. In addition, 9 checks with no salt treatment were set up. Superphosphate tagged with radioactive P was added to the soil, and after a period of incubation, each treatment was further divided into 5 replications. Total available P and available P coming from the fertilizer were then detd. The latter detn. was made possible by measuring the amt. of radioactivity in the available P extract. Each salt and level gave a significant difference in the amt. of total available P and the percentage of P coming from the fertilizer. Ca salts decreased the availability of P as the concn. increased whether added as CaCO3, CaCl2, or CaSO4- Mg salts released more P than Ca salts. The highest level of MgCO3 released the most P of this group. The availability of P was highest where Na2CO3 was present; in fact, twice as much was available in this case as where the largest amt. of CaCO3 was added.