Evaluation of a New Phosphorus Source in Vegetable Production.

The objective of this experiment was to evaluate the effectiveness  of Crystal Green®, an alternative fertilizer phosphorus source, and to compare this source to a standard P fertilizer source.  This one-year experiment was conducted at the Horticulture Unit of the EV Smith Research Unit, located in Shorter, AL.   The study consisted of a spring crop of sweet corn, followed by a summer crop of green pepper, with rates and sources of P fertilizer as the treatment variable.   P rates (as P) were 84 or 112 kg P ha^-1 (75 or 100 lb P A^-1), and P sources were either mono-ammonium phosphate (MAP) or Crystal Green.  At the 112 kg P ha^-1 rate the P source was: 1) 100% MAP, 2) 100% Crystal Green or, 3) a 50/50 blend of Crystal Green/MAP.  At the 84 kg P ha^-1 rate the P source was 100, 50, 25 or 0% Crystal Green, with the remainder P from MAP.  With a zero P control there were a total of 9 treatments, each replicated 4 times.  All P treatments were applied prior to planting bed formation and plastic mulch cover.  Collected data included plant tissue P content, fresh weight yield data, and post-harvest soil samples for Mehlich extractable soil P content.   Fresh weight of sweet corn increased as P rate increased, but the percentage of that P that was Crystal Green had no effect on yield of sweet corn.  In comparison, as the percentage of P that was Crystal Green increased (from 0 to 100% of the P) the yield of green pepper linearly increased.  Soil Mehlich extractable P also increased as the percentage of P that was Crystal Green increased.  In this one-year study there was some evidence that use of Crystal Green as a portion of the P fertilizer increased yield of green pepper, and increased extractable soil P.