Avail, a Dicarboxylic Acid Copolymer Increases the Agronomic Efficiency of Phosphate Fertilizer.

Increased yield responses of agricultural crops to phosphate fertilizers treated with Avail, a dicarboxylic acid copolymer, has been documented in a number of crops in several locations.   A summary of several multiple year studies on corn, barley, rice and canola demonstrates that Avail not only increases yield, but increase the Agronomic Efficiency (AE_N) of applied phosphate fertilizers.    AE_N=( Y_N- Y₀)/N, is calculated with Y_N=crop yield with an applied nutrient, Y₀=crop yield with no applied nutrients and N= amount of nutrient applied.  AE_N can be a useful tool in evaluating the efficiency nutrient treatments with in an experiment.  AE_N can also be used to compare nutrient efficiency between nutrient sources or increased efficiency products.  The % increase in AE_N=(AE_NAvail/AE_N)-100 provides useful insight in to the increased efficiency of applied phosphate fertilizer when treated with Avail.  Avail increased efficiency of 56 kg ha^-1 P₂O₅ to corn an average 74% in a 3 yr study.  In another study it increased efficiency of 45 kg ha^-1 P₂O₅ to corn an average 57%.  Avail increased the efficiency of 28 kg ha^-1 P₂O₅ to rice an average of 77%.  Avail increased the efficiency of 37kg ha^-1 P₂O₅ to canola an average of 63%.   Avail increased the efficiency of 30kg ha^-1 P₂O₅ to barley an average of 65%.   The effectiveness of phosphate fertilizer treated with Avail decreased as the amount of phosphate fertilizer increased.  The increase in AE_N in multiple year studies on several crops demonstrate the usefulness of Avail in protecting applied phosphate fertilizers from soil P fixation and thus increasing efficiency.