Evaluation of Gypsum Rates On Greenhouse Crop Production.

This study was to determine the potential of an added value distribution channel for gypsum waste by evaluating various greenhouse crops with captious pH and calcium needs.  Three studies consisting of:  Zonal geranium (Pelargonium x hortorum) and petunia (Petunia x hybrida); tomato (Solanum lycopersicum); and three varieties of ferns (Nephrolepis obliterata, N. exaltata, and N. exaltata ‘Roosevelt’) were grown using FGD gypsum rates of 5.5, 11, 16.5, and 22 lb/yd³.  (The tomato and fern studies included rates of 27.5 and 33 lb/yd³, and geranium and petunia study included 5 lb/yd³ dolomitic lime (DL) and 5 lb/yd³ DL + 5.5 lb/yd³ gypsum).  Geraniums and petunias showed no significant differences between treatments.  Two of the species of ferns did show significant differences in treatments, but there was no apparent pattern to those differences.  The occurrence of blossom end rot on the tomatoes was reduced by the addition of FGD gypsum.