Location: Horticultural Crops Research2011 Annual Report
1a. Objectives (from AD-416)
1) Evaluate blueberry plant growth, yield, and quality in various certified-organic production systems in two popular fresh-market cultivars; 2) determine the effect of raised beds on soil and plant water status and plant growth, and production; 3) evaluate and continue to develop organic weed management systems in producing blueberries; and 4) develop and evaluate organic fertilizer treatments to optimize plant growth, production, and quality.
1b. Approach (from AD-416)
Treatments being assessed include planting on raised beds or flat ground, various weed management treatments including weed mat, organic fertilization type and rate, and cultivar. We will collect information on not only the effectiveness of the treatments such as weed mat, sawdust and compost mulches and use of vinegar for weed control on flat ground and raised beds and organic fertilizers and how they interact with sawdust mulch and weed mat, but also the cost effectiveness. We will measure plant growth, yield, fruit quality, weed pressure, soil water status, plant water status, plant tissue and soil nutrient concentration, and organic fertilizer availability. We will make observations on any other pest problems and control them to the best of our ability using organically approved methods. We feel that this study will provide growers with very useful information on the long-term impacts and costs of various organic blueberry production systems during fruiting years.
3. Progress Report
A 0.4 ha (1 acre) planting of blueberry was established in October,2006 to evaluate the effects of cultivar (Duke and Liberty), bed type (flat versus raised beds), weed management [sawdust mulch and hand-weed control; sawdust+compost mulch with acetic acid, flaming, and hand control used as needed; and weed mat], and type and rate of fertilizer (feathermeal and liquid fish emulsion at 57 and 112 kg•ha-1 N) on plant growth, yield, fruit quality, irrigation requirements, and weed presence. The site was certified organic in 2008. In the establishment years, plants grown on raised beds were larger than those on flat ground, but they required more irrigation, particularly with weed mat. To date, weed mat has resulted in the fewest weeds, while sawdust+compost has had the most weeds. Cumulative yield from years 2-4 was 48% greater on raised beds than flat ground, corresponding to improved plant growth measured on raised beds in 2007 and 2008. Although the soil at this research site is considered to be well-drained, there was still an advantage of raised beds. Fertilization with the low rate of fish emulsion or the high rate of feather meal resulted in high yields in 2009 and 2010. In ‘Duke’, fertilization with the high rate of fish emulsion resulted in lower yields and lower average berry weight than with the low rate of fish emulsion or either rate of feather meal, but this was not the case in ‘Liberty’. Compost+sawdust and weed mat mulched plots produced greater yield than those mulched with sawdust in 2009 and 2010, though compost+sawdust had the highest yield in 2009. Both ‘Duke’ and ‘Liberty’ had lower fruit firmness when fertilized with the low rate of feather meal than with fish emulsion or the high rate of feather meal. Duke fruit were firmer and had higher percent soluble solids (Brix) when fertilized with a high rate of fish emulsion. Methods of project monitoring included meetings, e-mail, and phone calls.