Effect of Avail and JumpStart On Phosphorus Response in Corn and Wheat.

The increasing price of phosphorus (P) fertilizers has created interest among farmers in ways to enhance the efficiency of applied P fertilizers.  Two studies were designed to test the use of two widely advertised products:  Avail®, a long chain, organic polymer created to reduce the fixation of fertilizer P by aluminum and calcium, and JumpStart®, a penicilliam bilaii seed inoculant which increases the availability of native soil P to plant roots.  This project was conducted at multiple locations across Kansas with corn (Zea mays L.) in 2008 and 2009 and wheat (Triticum aestivum L.) in 2009. Sites ranged in available P, with the majority of the locations having a Mehlich 3 P soil test <20 mg kg^-1, where a P response would have been expected.  Treatments consisting of P rates (0 to 20 kg P ha^-1) with and without the addition of Avail (AV) were applied at planting.  At many locations each of the fertilizer/Avail treatment was planted with and without Jumpstart (JS) seed treatment.  Excellent corn yields, above 12,500 kg ha^-1, were obtained at all locations in 2008, with significant responses to applied P obtained at two of the three sites.  JumpStart increased yield at P responsive sites when no fertilizer P was applied, but not when P was applied.  No response to the use of Avail was seen in 2008.  Wheat responded significantly to applied P in 2009, but no response to either product was seen.