Improved Nitrogen Fertilizer Practices for Highbush Blueberry

There are currently more than 77,000 ha of cultivated blueberry (Vaccinium sp.) grown worldwide, and production is expected to increase by another 46% over the next 5 years. Eighty-seven percent of the crop is produced in North America and South America, but plantings are expanding into less traditional growing regions, including Mexico, Brazil, Peru, southern Europe, northern and southern Africa, Asia, and Australia. By 2015, total global production is predicted to reach 635,000 metric tonnes of blueberries per year.

Blueberry is a long-lived perennial crop (30+ years) categorized as a calcifuge, well adapted to acidic soil conditions. Plants thus acquire primarily the NH₄ form of N over NO₃-N and tolerate relatively low levels of P, K, Ca, and Mg in the soil and high concentrations of plant-available metals such as Mn and Al. Nutrient management guidelines for highbush blueberry are currently based on the use granular fertilizers. However, many new plantings are fertigated through drip systems, which, based on 4R principles, may have very different nutrient requirements than those fertilized using traditional practices.

A series of blueberry fertilizer trials have been established near Corvallis, OR. These field experiments are using several of the most common varietal material, so differences in genetics can also be evaluated.

• The first trial is comparing application of granular fertilizer with fertigated nutrition.
• The second trial is examining the use of one drip irrigation line per bed with the use of two drip lines per bed.
• The third trial is studying the efficacy of various commercial additives that are incorporated in the irrigation water of fertigated blueberries. These fluid treatments are compared with small amounts of granular fertilizer that are applied shortly after planting.

These blueberry experiments are examining the effects of nutrient management during the establishment phase of blueberries. IPNI support will also aid in the measurement of the treatment effects on fruit production in mature plants in the coming years.