LOWBUSH BLUEBERRY RESPONSE TO PHOSPHORUS FERTILIZATION.

Nutrition Surveys of commercial blueberry fields in 1987 and 1988 indicated leaf phosphorus levels were below the standard (0.125%) in most fields. To determine if phosphorus was limiting, liquid phosphorus (23% phosphoric acid) was applied preemergence at 0, 22.4, 44.8 67.2, or 88.6 kg/ha to 3 commercial blueberry fields identified in 1987 as very low (<.111%), 3 low (.111-.125%), and 3 adequate (>.125%) in leaf phosphorus. Phosphorus concentration in leaf tissue sampled in July 1989 increased linearly with increasing rates of phosphorus. Phosphorus application raised leaf phosphorus levels more in fields which had levels below 0.125%. Fields with higher phosphorus levels were also higher in leaf nitrogen, potassium, and calcium.