Organic greenhouse soil media + supplemental fertilizer = better organic tomato transplants

Authors: Webber Iii, Charles; ROBERTS, B - Oklahoma Agriculture Experiment Station

Submitted to: Proceedings of Horticultural Industry Show
Publication Type: Proceedings
Publication Acceptance Date: 1/29/2010
Publication Date: 4/1/2010
Citation: Webber III, C.L., Roberts, B.W. 2010. Organic greenhouse soil media + supplemental fertilizer = better organic tomato transplants. In: Dollins, D. editor. Proceedings of the 29th Annual Horticulture Industries Show, January 8-9, 2010, Tulsa, Oklahoma. p. 163-164.

Interpretive Summary: It was necessary to develop organic certification to provide consistent standards across the U.S. for the benefit of producers, processors, wholesalers, retailers, and consumers. All components entering into the organic crop production system must be approved for organic use, including seed, soil media, and fertilizer used in transplant production. Research was conducted to determine whether the addition of supplemental fertilizer to an organic soil medium enhances seedling growth. The factorial experiment included 4 preplanting fertilizer treatments, 0-0-0 (control), 5-4-4, 6-2-2, and 7-3-7 N-P-K, added at 1% by weight to an organic potting medium prior to planting organic tomato (Solanum lycopersicon L.) seeds ('Florida 47'), and 2 liquid fertilizer rates, 0.4% and 0% (control) added at 3 weeks after planting (WAP). All components (potting medium, seed, and fertilizer were from organic sources). There were 6 replications with 6 plants per replication. Adding fertilizer prior to planting produced significantly greater plant heights at 3 and 5 weeks (WAP) compared to the control (0-0-0). There were few height differences due to fertilizer treatment at 3 WAP. However, addition of 0.4% solution of a fish and seaweed fertilizer at 3 WAP resulted in a significant height increase at 5 WAP for the 6-2-2 fertilizer treatment. To produce suitable tomato transplants supplemental fertilizer was required at a level of 1% by weight of a 6-2-2 N-P-K organic fertilizer, which was further enhanced by applying a 0.4% solution of a fish and seaweed fertilizer at 3 WAP. Further research should investigate additional organic soil media, fertilizer sources and rates, and crops.

Technical Abstract: Consumer perceptions that organic food tastes better and is healthier are two major factors driving the increasing demand for organically produced crops in the U.S. All components entering into the organic crop production system must be approved for organic use, including seed, soil media, and fertilizer used in transplant production. Research was conducted to determine whether the addition of supplemental fertilizer to an organic soil medium enhances seedling growth. The factorial experiment included 4 preplanting fertilizer treatments, 0-0-0 (control), 5-4-4, 6-2-2, and 7-3-7 N-P-K, added at 1% by weight to an organic potting medium prior to planting organic tomato (Solanum lycopersicon L.) seeds ('Florida 47'), and 2 liquid fertilizer rates, 0.4% and 0% (control) added at 3 weeks after planting (WAP). All components (potting medium, seed, and fertilizer were from organic sources). There were 6 replications with 6 plants per replication. Adding fertilizer prior to planting produced significantly greater plant heights at 3 and 5 weeks (WAP) compared to the control (0-0-0). There were few height differences due to fertilizer treatment at 3 WAP. However, addition of 0.4% solution of a fish and seaweed fertilizer at 3 WAP resulted in a significant height increase at 5 WAP for the 6-2-2 fertilizer treatment. To produce suitable tomato transplants supplemental fertilizer was required at a level of 1% by weight of a 6-2-2 N-P-K organic fertilizer, which was further enhanced by applying a 0.4% solution of a fish and seaweed fertilizer at 3 WAP.