A greenhouse experiment was conducted from June to September 2011 to evaluate the effects of three organic and one mineral fertilizers on the growth of Green lettuce, Sweet epper and Swiss chard. One hundred and twenty pots were filled with Fafard organic soil and amended with Cottonseed meal (6-2-1), Dried Blood (12-0-0) and Garden Food (4-3-2); and NPK13-13-13. A control treatment (non-amended Fafard organic soil) was also included in the study. The experimental design was a completely randomized block with 5 fertilizer treatments and 3 vegetables replicated 8 times. Plants were harvested at the end of each month and growth parameters were measured. Results showed that as expected, all growth parameters were significantly affected by vegetable types, from the first to the fourth month of growth. However, for fertilizers, the number of leaves (p=0.043), plant fresh weight (p=0.037), plant dry weight (p=0.021) and leaf area (p=0.054) were significantly affected by fertilizers in the fourth month of study only. Among vegetables, Green lettuce had highest growth as compared to the other two vegetables. Cottonseed gave better growth than NPK 13-13-13 and the other organic fertilizers. These first year results suggest that organic fertilizers can affect plant growth more significantly than mineral fertilizers. However, more studies need to be conducted to confirm these results.
Abstract of Poster presentation at MISSOURI ACADEMY OF SCIENCE, 2012 (April 4), University of Missouri-Columbia