Location: Horticultural Crops Research UnitTitle: Benefits of using liquid sources of potassium fertilizer in northern highbush blueberry
Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/18/2018
Publication Date: 2/7/2019
Citation: Bryla, D.R., Leon, D., Orr, S.T. 2019. Benefits of using liquid sources of potassium fertilizer in northern highbush blueberry. Symposium Proceedings from North American Blueberry Research and Extension Workers Conference in Orono, Maine from August 12-15, 2018.
Technical Abstract: Fertigation with N increases growth and production relative to granular N applications in northern highbush blueberry (Vaccinium corymbosym L.), but little information is available on whether there is any benefit to fertigating with other nutrients. The objective of this study was to compare fertigation to granular application of K fertilizer in a mature planting of ‘Duke’ blueberry. The plants were grown on raised beds and irrigated using two lines of drip tubing per row. Treatments were initiated in 2016 and included fertigation (once a week from April to August) with potassium sulfate or potassium thiosulfate (KTS), a single application (April) of granular potassium sulfate, and no K fertilizer. Each K fertilizer was applied at a total rate of 75 kg/ha K2O per year. So far, the treatments have had no effect on yield or fruit quality. However, fertigation with potassium sulfate 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 potassium sulfate, while granular potassium sulfate resulted in higher concentration of K than any other treatment at 6 inches from the drip emitter (edge of the wetting front). The fertigated treatments also had greener leaves (based on SPAD meter readings), greater 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.