Conference Paper or Lecture

Many blueberry growers in South Georgia have expressed interest about using humate as a soil amendment and its effect on fruit production. Presently, pine bark is used to amend soils to increase organic matter and lower pH. Pine bark, generally, is applied at a rate of 100 cubic yards per acre, with a cost from $800.00 to $1,200.00/A. To alleviate establishment costs, some growers incorporate Leonardite and/or its extracts, humic and fulvic acids, to increase organic matter. To extract humic and fulvic acid, the Leonardite is processed in a strongly basic aqueous solution, e.g. KOH. To precipitate the humic acid, the solution is adjusted to pH 1 with a mineral acid, e.g. H2SO4. Three Leonardite products, two humic acids and one unextracted Leonardite, were analyzed for nutrient content. Calcium levels were 5000 ppm in both extracted samples and 2070 ppm in the unextracted Leonardite. Potassium levels were 977 and 800 ppm in the extracted samples and 125 ppm in the unextracted Leonardite, suggesting humic acid reacted with KOH. Research on Leonardite products and the effect on blueberry production are limited. Rates of humate in ornamental horticulture suggest using 3% – 12% v/v% in potting media. This equates to 30 – 120 t for equivalent additions on a per acre basis. At these rates, the application of calcium will be 124 – 1200 lb/A. Establishing blueberry at levels of 900 lb/A calcium is not recommended. The analysis of these Leonardite products is insightful as soil nutritional amendments to blueberry.

Paper presented at NABREW Conference, Paper Session I:Blueberry Culture, on June 24, 2014, Atlantic City, N.J.

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doi:10.7282/T38S4RM6

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