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48th TWC, Tob. Work. Conf., 2018, abstr. 18

Evaluations of float water aeration in organic transplant production

(1) North Carolina State University, Raleigh NC USA; (2) North Carolina Department of Agriculture and Consumer Services, Raleigh NC USA

At present, the effects of float bed aeration in the production of organic tobacco seedlings are not known. Research was conducted to evaluate two organic nitrogen fertilizer programs and their effects to float water nutrient concentration and seedling growth. Treatments evaluated consisted of 12-11-2 Peruvian Seabird Guano (SG) or a combination of SG + 16-0-0 Sodium Nitrate (SN). A conventional fertilizer source (SQM 16-5-16) was included for comparison. Each fertilizer source was evaluated with and without the continuous addition of oxygen from a Hydor H2Show Bubble Maker. Dissolved oxygen (DO) concentration was maintained at 5.5 to 7.5 mg oxygen/L in aerated treatments. In the absence of aeration, DO concentration was commonly ≤1.0 mg oxygen/L in SG treatments measured 25 or more days after seeding (DAS). Aeration reduced bicarbonate concentration by 50-83% and promoted the oxidation of ammonium-nitrogen to nitrate-nitrogen must faster than non-aerated treatments. Slight differences were observed in seedling usability and vigor, with aeration and SG+SN treatments producing higher quality seedlings than SG alone. Results indicate that float bed aeration is beneficial in the production of organic tobacco seedlings and can be used to reduce bicarbonate concentration while promoting ammonium oxidation. (Reprinted with permission)