This study was conducted to assess the effect of Ca-sulfate. Mg-sulfate or K-sulfate applied at equivalent rates to the top of soil column on the recovery of Ca. Mg, K and Na in leachates and on their mobility within soil columns. The changes in concentrations of exchangeable cations in leachates corresponded to the changes in ionic strength (/). The effect of the amendments on recovered Ca could be arranged in this order: K-sulfate > Mg-sulfate > Ca-sulfate (R2) > Ca-sulfate (Rl). Application of high quantities of K and Mg in highly soluble forms resulted in the displacement of Ca from the exchange sites, thus resulting in an increased transport of Ca. Magnesium released as a result of using K-sulfate was almost three times that recovered from the second rate of Ca-sulfate. The effectiveness of various treatments on the recovery of K could be arranged in this order: K-sulfate > Ca-sulfate (R2) > Mg-sulfate > Ca-sulfate (Rl). and the influence of soil amendments on released Na followed this sequence: Ca-sulfate (R2) > Ca-sulfate (Rl) > K-sulfate > Mg-sulfate. The effectiveness of Ca-sulfate in replacing Na over the other soluble amendments (Mg-and K-sulfate) was indicated. Using Mg-and K-sulfate decreased the exchangeable Ca in the top layers, but increased it slightly in the lower ones. The exchangeable Mg was low in the top layer (0-2cm) with all treatments and increased with all of them in the middle layers (7-17 cm). Applied Mg-or K-sulfate dissolved completely in the top layer and causing Mg or K ions move by the convective flow to the deeper layers or out of the columns. The effect of K-sulfate on the mobility of Mg was more obvious since the less amounts of exchangeable Mg in different layers were recorded with K-sulfate treatment. Exchangeable Na was high in the unamended soil (control) indicating undoubtably the need for another replacing cation to displace it from the exchange sites. Applying Mg-sulfate decreased exchangeable Na in all depths as compared to Ca-sulfate or unamended soil |
