Slide 5b.   Toowoomba ag chemical consultant Col Schiller (left) and Soil Scientist Gary Ham (BSES, Ayr, Queensland) examine a simple gypsum dissolvinator that can be constructed on site by farmers.  These more rudimentary systems use a coarser and less expensive grade of gypsum.  These systems are less automated, than the type seen in the previous slide, thus requiring more operator intervention, and may be less controlled or consistent in their delivery of calcium.  However, good results have been reported where the overriding need is to overcome existing high sodium levels in irrigation water or in soil profiles.  Similarly if the main desire is to elevate calcium in irrigation waters to improve soil surface structure, and/or improve efficacy of applied PAM, this type of system could be cost effective, simple to construct and operate, and reliable for the job required on most farms.