ARS | Publication request: Fertigation with liquid fish emulsion for organic production of highbush blueberry

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 12, 2012
Publication Date: June 17, 2012
Citation: Valenzuela-Estrada, L.R., Bryla, D.R., Sullivan, D.M., Strik, B.C. 2012. Fertigation with liquid fish emulsion for organic production of highbush blueberry. Meeting Abstract. Meeting booklet.

Technical Abstract: Liquid fish emulsion is a common fertilizer used for organic production of highbush blueberry. The product is often applied by hand or with a sprayer but can also be injected through a drip irrigation system, otherwise referred to as fertigation. Fertigation is more efficient and less labor-intensive than hand or spray application, but drip application limits availability of fertilizer nutrients to the dripper point, and particulates in the fish emulsion may clog the drip emitters. In this study, we examined the potential of applying liquid fish fertilizer by fertigation in an organic blueberry trial. Plants were established in Oct. 2006, on flat or raised beds mulched with sawdust or weed mat, and were irrigated by drip. Fish emulsion was initially applied by hand in 2007-10, but in 2011, was injected through the drip system, bi-weekly from early April to late June, at rate of 10 kg/ha N per application. To determine soil N concentrations following fertigation, soil solution was collected twice in April using 10-cm long suction lysimeters installed vertically, near a drip emitter in each plot, and at 15 and 30 cm from the emitter on both sides of the bed. Fertigation had no effect on drip flow rate and caused no apparent problems to date with emitter plugging. Following fertigation, N concentrations in soil solution were similar among bed type and mulch treatments when measured at the drip emitter but were higher in raised beds and under weed mat at 15 and 30 cm from the emitter. Most of the N in solution was nitrate-N and, on average, was five times higher in concentration at the emitter than at 15 cm and 30 cm but similar between 15 and 30 cm. Nitrification of ammonium- to nitrate-N increases with temperature, and soil temperature was often warmer in raised beds and under weed mat than in flat beds or under sawdust. Thus, once converted to nitrate, N mineralized from the fish fertilizer was dispersed in the soil with further irrigation. Fertigation with fish was successful so far and appears to be a good tool for fertilizing organic blueberry fields.