The 2011 ASHS Annual Conference

There are relatively few studies on fertilization and nutrition of organic vegetable transplants.  This study was intended to determine the effects of the rate of application of blood meal (BM) and feather meal (FM) on the germination of tomato (‘Brandywine’) seeds.  Both organic fertilizers were applied as amendments to peat-based organic medium at rates ranging from 0 to over 50 g∙kg^-1 N.  Tomato seed were sown in styrofoam trays and grown in the greenhouse. Seed germination was recorded daily until the germination percentage remained unchanged. Germination percentage of tomato was inhibited at rates higher than 5.4 g∙kg^-1 N BM (3.7% BM, by weight) and 8 g∙kg^-1 N FM (6.3% FM, by weight).  Germination percentage was 0% at 8 g∙kg^-1 N and 25 g∙kg^-1 N with BM and FM, respectively.  The pH of the medium decreased from 7.8 (at 0 mg∙kg^-1 N) to about 6.3 (at 8 g∙kg^-1 N ) with increasing fertilization rates, and then increased to about pH 8.0 (BM) and pH 7.5 (FM) with further increments in fertilization rates.  In conclusion, blood meal and feather meal are rich sources of N but, to avoid possible toxicity of tomato seeds and seedlings, they should not be used at concentrations higher than about 4% (by weight) and 6%, respectively.