An overview of fertilization and irrigation management in the conventional and certified organic production of vegetable crops in Florida

Abstract

The postharvest quality of vegetable crops from conventional and organic production systems depends on pre-harvest factors such as variety genetic potential, fertilization, and irrigation. The five principles of plant nutrition (plants absorb ions, not fertilizers; Leibeig’s law of the minimum; nutrient application requires a source, a rate, a placement and a time of application; no correlation exists between total nutrient presence in the soil and availability; and plant nutrient concentration and yield are related) must be followed throughout the crop growth cycle. In certified organic production in the United States, cover crops, manure and composts may be used together with Organic Materials Review Institute–approved fertilizer products. A fertilization program usually includes (1) soil sampling and understanding the recommendation; (2) adjusting pH if necessary; (3) applying preplant fertilizer and developing a schedule for sidedressing or fertigation; (4) using foliar fertilization; (5) monitoring plant nutrient status; and (5) keeping fertilization records. The components of an irrigation schedule are (1) determining a target irrigation volume based on reference evapotranspiration and crop age; (2) adjusting this amount based on soil moisture content; (3) determining the contribution of rainfall; (4) developing a rule for splitting irrigation; and (5) keeping irrigation records. A poorly designed irrigation program can negate the benefits of a sound fertilization program. Challenges encountered in conventional and organic production include predicting nutrient release rates from organic materials, supplying enough N throughout the cropping season, identifying rescue strategies, keeping production costs low, and meeting the additional legal requirements of the food safety and best management practices programs.