Presentation Type

Proceeding Paper

Publication Date

8-13-2018

Subject Category

Blueberry Culture

Description

Fertigation with N increases growth and production relative to granular N applications in northern highbush blueberry (Vaccinium corymbosum L.), but little information is available on whether there is any benefit to fertigating with other nutrients. The objective of this study was to evaluate the use of K for fertigation. An initial study was done in a greenhouse to identify appropriate combinations of liquid N and K sources for fertigation using potted plants of ‘Duke’ blueberry. The results indicated that the concentration of K in the soil solution increased by 25% with potassium sulfate (K2SO4) and by 39% with potassium thiosulfate (KTS) and, depending on the soil type, was highest when KTS was applied with urea or ammonium sulfate. Leaf K was affected by K as well as N fertilizers and, on average, was greater with than without K in both an optimum and high pH soil and with KTS than with K2SO4 in the latter soil. A second study was conducted to compare fertigation to granular application of K fertilizer using a mature planting of ‘Duke’ blueberry. Treatments included fertigation (once a week from April to August) with water-soluble K2SO4 or KTS, a single application (April) of granular K2SO4, and no K fertilizer. Each K fertilizer was applied at a total rate of 84 kg/ha K2O per year. After 2 years, the treatments have had no effect on yield or fruit quality. However, fertigation with K2SO4 or KTS resulted in lower pH and higher concentrations of K, Ca, Mg, and S in soil solution under the drip emitters than either no K or granular K2SO4, while granular K2SO4 resulted in higher concentration of K than any other treatment at 15 cm from the drip emitter (edge of the wetting front). The fertigated treatments also had greener leaves (based on SPAD meter readings), greater whole-plant leaf K concentrations, and nearly twice as much extractable K in the soil as the non-fertigated treatments. Additional measurements are underway to determine whether K fertigation will have any effect on yield or fruit quality over the long term.

Start Date

13-8-2018 11:40 AM

End Date

13-8-2018 12:00 PM

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Aug 13th, 11:40 AM Aug 13th, 12:00 PM

Benefits of using liquid sources of potassium fertilizer in northern highbush blueberry

Fertigation with N increases growth and production relative to granular N applications in northern highbush blueberry (Vaccinium corymbosum L.), but little information is available on whether there is any benefit to fertigating with other nutrients. The objective of this study was to evaluate the use of K for fertigation. An initial study was done in a greenhouse to identify appropriate combinations of liquid N and K sources for fertigation using potted plants of ‘Duke’ blueberry. The results indicated that the concentration of K in the soil solution increased by 25% with potassium sulfate (K2SO4) and by 39% with potassium thiosulfate (KTS) and, depending on the soil type, was highest when KTS was applied with urea or ammonium sulfate. Leaf K was affected by K as well as N fertilizers and, on average, was greater with than without K in both an optimum and high pH soil and with KTS than with K2SO4 in the latter soil. A second study was conducted to compare fertigation to granular application of K fertilizer using a mature planting of ‘Duke’ blueberry. Treatments included fertigation (once a week from April to August) with water-soluble K2SO4 or KTS, a single application (April) of granular K2SO4, and no K fertilizer. Each K fertilizer was applied at a total rate of 84 kg/ha K2O per year. After 2 years, the treatments have had no effect on yield or fruit quality. However, fertigation with K2SO4 or KTS resulted in lower pH and higher concentrations of K, Ca, Mg, and S in soil solution under the drip emitters than either no K or granular K2SO4, while granular K2SO4 resulted in higher concentration of K than any other treatment at 15 cm from the drip emitter (edge of the wetting front). The fertigated treatments also had greener leaves (based on SPAD meter readings), greater whole-plant leaf K concentrations, and nearly twice as much extractable K in the soil as the non-fertigated treatments. Additional measurements are underway to determine whether K fertigation will have any effect on yield or fruit quality over the long term.