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Title: Liquid corn and fish fertilizers are good options for fertigation in blackberry cultivars grown in an organic production system

item FERNANDEZ-SALVADOR, JAVIER - Oregon State University
item STRIK, BERNADINE - Oregon State University
item Bryla, David

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/18/2014
Publication Date: 2/28/2015
Citation: Fernandez-Salvador, J., Strik, B.C., Bryla, D.R. 2015. Liquid corn and fish fertilizers are good options for fertigation in blackberry cultivars grown in an organic production system. HortScience. 50(2):225-233.

Interpretive Summary: A three-year study was conducted in Oregon to determine the impact of using different organically-approved liquid fertilizer sources, corn steep liquor and a fish solubles and molasses blend, on growth, yield, and fruit quality in trailing blackberry. The site was certified organic and included two cultivars, ‘Marion’ and ‘Black Diamond’. The cultivars are predominantly harvested by machine for high-value processed markets and together account for >75% of the blackberries produced in Oregon. The plants were irrigated by drip, and both fertilizers were easily injected through the drip system with only minor problems with emitter plugging. Overall, ‘Black Diamond’ had greater total yield and average fruit weight than ‘Marion’, but neither fertilizer had any effect on yield, even though the size of the berries was slightly larger with corn steep than with the fish blend. While the fertilizers contained different amounts of many nutrients, including P, K, Ca, Mg, Fe, B, Cu, Mn, Zn, and Na, both supplied sufficient amounts of most nutrients to the plants, except for Ca and B. Thus, both fertilizers appear to be good options for organic production of blackberries, but may require additional application of organically approved Ca and B fertilizers.

Technical Abstract: The impact of organic fertilizer source on growth, fruit quality, and yield of two cultivars ('Marion' and 'Black Diamond') blackberry grown organically for the processed market. The planting was established in spring 2010 and was certified organic in 2012. Plants were irrigated using a drip line under a woven polyethylene ground cover (weed mat) installed for weed management. Two sources of liquid fertilizer were evaluated: 1) a corn steep liquor and fish waste digestion, and 2) a fish solubles and molasses blend. Fertilizers were applied by fertigation through the drip system at rates of 56 kg/ha N per year in 2011-2012 and 90 kg/ha N in 2013. Drip system performance was evaluated with two maintenance options, “flushing” and “no flushing” of the drip lines. 'Black Diamond' had greater total yield and average fruit weight than ‘Marion’, but produced the most unmarketable fruit. There was no effect of fertilizer source on yield, fruit quality, primocane length, or primocanes/plant in any year, with the exception of fruit weight, which was greater with corn than with fish. ‘Marion’ had a greater floricane biomass when fertilized with fish than with corn. Soil nutrients were within the recommended range, except for B, which was below recommended levels; and only soil nitrate-N was affected by fertilizer source, which was greater in ‘Marion’ than in ‘Black Diamond’ when fertilized with fish. Primocane leaf tissue nutrient concentrations were within recommended levels for all nutrients, except for Ca and B which were below recommended standards in both cultivars. Primocane leaf K and Zn concentrations were greater with fish than with corn. There was no fertilizer source or maintenance effect on emitter flow rate of the drip system in either year. However, flow rates decreased an average of 4.5% in the first year and 19% in the second year. Overall, there were no differences between the fertilizers on plant growth, yield, or fruit quality, and both fertilizers were suitable for planting establishment.