Location: Horticultural Crops Research UnitTitle: Organic production systems in northern highbush blueberry: I. Impact of planting method, cultivar, fertilizer, and mulch on yield and fruit quality from planting through maturity
|STRIK, BERNADINE - Oregon State University|
|VANCE, AMANDA - Oregon State University|
|SULLIVAN, DAN - Oregon State University|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2017
Publication Date: 10/1/2017
Citation: Strik, B.C., Vance, A., Bryla, D.R., Sullivan, D.M. 2017. Organic production systems in northern highbush blueberry: I. Impact of planting method, cultivar, fertilizer, and mulch on yield and fruit quality from planting through maturity. HortScience. 52(9):1201-1213. https://doi.org/10.21273/HORTSCI12179-17.
Interpretive Summary: Organic blueberry production has increased in the Pacific Northwest due to strong consumer demand, price premiums of 20-200% over conventional fruit, and a dry summer climate, which reduces the potential for weeds, insect pests, and leaf and fruit diseases.The objectives of this research trial were to evaluate the impact of planting method (flat ground or raised planting beds), cultivar (Duke and Liberty), mulch (sawdust, yard debris compost covered with sawdust, or weed mat) and fertilizer (fish emulsion or feather meal) on plant growth, yield, and fruit quality from establishment through maturity. When we initiated the study in 2006, the most common organic production system in the region was raised beds mulched with sawdust and fertilizing with a high rate of fish emulsion. With this production system, yield of ‘Duke’ and ‘Liberty’ was equal to 4.0-5.5 ton/acre and 5.3-10.6 ton/acre, respectively, depending on year. We found that raised beds with weed mat and a high rate of feather meal increased yield by 20% in ‘Duke’. Yield was also 22% greater on raised beds than on flat ground and 11% greater with weed mat than with sawdust or compost + sawdust in ‘Liberty’. Adding compost to the mulch increased weeds and, therefore, made this treatment cost prohibitive. It is clear that choice of the organic production system can have a significant impact on yield, production costs, and net returns.
Technical Abstract: A long-term trial was established to identify organic production systems for maximum yield and quality in highbush blueberry. Treatments included raised beds or flat ground; granular feather meal or fish solubles at low and high rates; sawdust, yard debris compost topped with sawdust, or weed mat; and ‘Duke’ and ‘Liberty’. Raised beds resulted in greater yield than flat ground during the establishment years but had less effect on yield once the plants were mature. After 9 years, cumulative yield was 22% greater on raised beds than on flat ground in ‘Liberty’ but was not affected by planting method in ‘Duke’. Cumulative yield was also 10% greater with feather meal than with fish solubles, on average, and 4% greater with a low rate than with a high rate of fertilizer. ‘Duke’ was particularly sensitive to the fertilizers and produced 35% less yield overall with fish solubles than with feather meal. In contrast, there was little effect of fertilizer on ‘Liberty’. In 5 of 9 years, yield was 8-20% greater with weed mat than with sawdust or compost + sawdust. Mulch type had no effect on cumulative yield of ‘Duke’, but cumulative yield of ‘Liberty’ was 11% greater with weed mat than with sawdust or compost + sawdust. Soil temperature was warmer under weed mat than under sawdust, and plants on raised beds covered with weed mat required more irrigation than those grown on flat ground mulched with sawdust. On average, ‘Duke’ berries were softest when fertilized with feather meal and firmest with a high rate of fish. In ‘Liberty’, the low rate of feather meal produced softer fruit than the other fertilizer treatments. ‘Duke’ produced heavier, larger, and firmer berries with lower total soluble solids than ‘Liberty’. However, other treatment effects on berry quality were relatively small and inconsistent. For example, berry weight was greater on raised beds than on flat ground, on average, but only by 3%. Our results showed that choice of organic production system can have significant impact on yield and economic costs and returns.