Evaluating Nutrient Management Systems for Organically Produced Greenhouse Colored Bell Pepper (Capsicum annuum L.)

Greenhouse vegetable systems can be certified organic by a United States Department of Agriculture accredited certification agency, but these systems are typically focused on transplant production.  Higher price premiums associated with greenhouse and certified organic produce (compared with field and conventionally-grown produce) distinguishes organic greenhouse vegetable production as a strong market incentive and a potentially viable, scale-neutral opportunity for growers.  Successful non-chemical pest management strategies that have been adopted by greenhouse growers, including biological control, are consistent with the National Organic Program’s Final Rule.  However, growing media, fertilizer source and application strategies remain important and challenging issues for organic greenhouse production.  The objective of this project was to identify the organic greenhouse nutrient management system that produces the greatest yield and quality of red bell pepper (Capsicum annuum L. ‘X3R Red Knight’) while maintaining economic sustainability.  Treatments that varied in container growing media (three levels) and fertilizer source (five levels) were arranged in a randomized complete block design with four replications in an experiment conducted at the University of Florida’s Protected Agriculture greenhouses near Citra, FL in fall of 2010.  Organic media treatments were a 1:1 ratio (by volume) of peat and pine bark without compost, with 30% yard waste compost, or with 30% poultry litter compost.  Four organic fertilizer regimes included dry granular sources only, a nutrient solution delivered through the irrigation system only, a combination of granular sources applied at planting and nutrient solution beginning at sidedress, and a combination of nutrient solution beginning at planting and granular sources applied at sidedress.  The organic systems were compared to a conventional hydroponic fertilization regime of mineral-based nutrient solution applied through the irrigation system.  Throughout the season, data was collected on plant height, leaf nitrogen status using a SPAD meter, and the pH, electrical conductivity and nutrient concentrations of leachate samples.  At harvest, data was collected on fruit yield and quality and whole plant fresh and dry weight.  Peat and pine-bark substrate amended with poultry litter compost and fertilized with either combination of organic granular and nutrient solution sources produced the highest organic marketable yields of 71-83% of the hydroponic control.  It is anticipated that this research will significantly contribute to sound recommendations for nutrient management strategies for sustainable organic greenhouse colored bell pepper production.