Impact of Fertilizer Regime on Yield and Food Safety of Heirloom Tomato Grown on Conventional and Organic Field Sites.

In recent years, American consumer trends have indicated a rise in food nutrition awareness and organic produce, particularly with agricultural commodities. This increased sensitivity has led to a greater demand for agricultural food grown without the addition of synthesized products, or rather those which are raised using organic methods. Due to limited access and availability of approved organic fertilizers, many farmers resort to the use of natural sources, such as animal manure for nutrient enrichment. This practice introduces its own set of challenges, namely the potential to be a harbor for pathogenic bacteria which can subsequently contaminate crops and is an avenue for water source pollution through runoff. These challenges have validated the need to research alternative fertilizer sources, in addition to manure, to determine their effects on crop growth as well as the likelihood for pathogen contamination. In this study, two approved organic fertilizers and a synthetic conventional fertilizer were used in comparison and conjunction with poultry manure to examine their effects on Debarao Plum and Brandywine tomato, (Lycopersicon esculentum) yield and microbial integrity, as grown organically and conventionally. Results indicate that fertilizer regime had no significant impact on overall tomato yield in either conventional (ranging from 2,207 to 5,081 kg/ha) or organic (ranging from 8,165 to 9,759 kg/ha) growth operations. Microbial integrity also proved to be of no consequence as fertilizer type had no significant influence on tomato fruit quality. Salmonella and generic E. coli were not detected on tomato fruits; however, generic E. coli was detected randomly in soil samples of a few tomato plots. Conclusions from this study indicated that fertilizer source does not contribute to productivity of Debarao Plum or Brandywine tomato varieties as long as the crop’s nutrient requirements are met. In addition, fertilizer type had no direct influence on pathogen contamination. Factors to consider in this finding are the age of poultry manure used, the amount of time that lapses between manure application and crop harvest, and whether the manure was treated with any process that would create a non-conducive environment for bacteria proliferation.