RUSSET BURBANK POTATO PHOSPHORUS FERTILIZATION WITH DICARBOXYLIC ACID COPOLYMER ADDITIVE (AVAIL (R))

Improving P use efficiency (PUE) is desirable but difficult due to poor phosphorus (P) solubility in soils. A dicarboxylic acid copolymer (AVAIL (R)) fertilizer additive may enhance PUE. Monoammonium phosphate (MAP) at 67kg P2O5 ha(1) was applied with or without AVAIL addition compared to an untreated check applied to potato on five field sites. MAP + AVAIL resulted in significant US No. 1 and total yield increases at two and three sites, respectively. Generally, the other sites showed similar trends. However, MAP + AVAIL resulted in a significant decrease in yields at one site possibly due to a P-induced micronutrient deficiency. Petiole P concentration of MAP + AVAIL-treated plants was significantly greater than the other treatments at mid and late season sampling dates at all sites. Addition of AVAIL with MAP applied to potato was generally effective, but concurrent fertilization with micronutrients is likely warranted due to possible antagonism with P.