Organic spinach is among the top organic vegetables sold in the United States, and growth of spinach production tops the list. Climatic conditions have limited spinach production in the southeastern U.S., where high humidity and warm temperatures negatively affect spinach growth and quality. Florida’s climate also includes drastic variations in temperatures during the spinach growing season. High tunnel system and appropriate cultivar selection has the potential to mitigate many of these environmental extremes, yet there is a lack of research-based information on organic spinach production under Florida conditions. Additionally, compost application may help overcome spinach germination difficulties, which is a challenge to growers particularly in warm climates. Given the growing interest in spinach production in Florida, the objectives of this project are to (1) identify the current spinach production practices of organic farmers and challenges of organic spinach production in Florida to understand the range of issues and most common difficulties faced; (2) assess the effects of cultivar, compost, and high tunnel system on organic spinach production to develop techniques which help mitigate identified common difficulties; and (3) disseminate research information through a growers’ workshop and presentation at the Florida State Horticultural Society conference. This research will address the SARE targeted issues by (1) identifying production methods and systems that help overcome production challenges, improve environmental quality, and promote crop diversity, (2) developing cultivar and compost management recommendations towards improving organic farming methods for growers in the South, and (3) improving quality of life of local growers and consumers by enhancing production of spinach, a widely consumed health-promoting, nutrient-dense leafy vegetable.
The goal of this research is to identify production techniques that promote sustainable spinach production in Florida.
Objective 1: Identify the current spinach production practices of organic farmers and challenges of organic spinach production in Florida to understand the range of issues and most common difficulties faced.
Objective 2: Assess the effects of cultivar, compost, and high tunnel system on organic spinach production to develop techniques which help mitigate identified common difficulties.
Objective 3: Disseminate research information through a growers’ workshop and presentation at the Florida State Horticultural Society conference.
A preliminary, winter trial was conducted at the Plant Science Research and Education Unit (PSREU) in Citra, FL, to build on previous spinach research at the University of Florida. A split-split plot design was utilized, with the production system (high tunnel and open field) as the whole plot factor, compost application method (tilled and furrowed) as the subplot factor, and compost type (plant based and cow manure based) and rate (0, 10, and 20 tons per acre) as the sub-subplot factor. Soil samples were taken at planting to explore treatment effects on physical, chemical, and biological soil quality indicators. Germination data was captured via the Canapeo App (www.canopeoapp.com), which calculates the amount of green in a picture frame. Harvest units were established by thinning plants to 3 inch spacing in order to eliminate germination effects and assess plant growth rates on a per plant basis. Spinach was harvested 50 days after seeding for fresh weight, dry weight, and nutrient analysis.
A high tunnel spring trial is currently underway to assess compost treatments in organic spinach production in another high tunnel location at PSREU. A split plot design was used, with the seeder type (Earthway and Jang) as the whole plot factor and compost application method (tilled and furrowed) in combination with rate (0, 10, and 20 tons per acre) as the subplot factor.
Results showed lower bulk density, higher CEC and nutrient content, and higher total carbon and organic matter in furrowed treatments than tilled treatments, and no significant differences between tilled treatments and the control. Other physical and biological indicator analyses are ongoing.
Significant germination increases were found with increasing amount of compost additions in the furrowed treatment, while the tilled treatment was not significantly greater than the control. Additionally, germination was greater in the cow manure based compost than the plant based compost, most likely due to the poorer quality (larger particle size) of plant based compost received.
Fresh weight revealed no significant differences in growth rates between compost treatments, while high tunnel yields were 174% greater than the open field, due to an increase in both leaf number per plant and leaf size. Dry sample analysis is ongoing.
Educational & Outreach Activities
The graduate student visited six spinach growers from north, central, and south Florida and corresponded with a few others. Interestingly, there are numerous conventional spinach growers who are only limited by the subtropical heat of Florida’s summers. For organic growers, spinach cultivation is so difficult that the majority do not even attempt to grow it. Poor germination and/or lack of crop stand are the common reasons organic growers keep spinach as a periphery crop. A grower survey is now being developed to further explore these obstacles with a wider audience of growers to identify opportunities for research to alleviate these production challenges and increase organic spinach production in Florida.
Preliminary results from the winter trial were presented at the Southern Region – American Society of Horticultural Sciences in Jacksonville, FL.
A grower survey is now being developed to further explore these obstacles with a wider audience of growers to identify opportunities for research to alleviate these production challenges and increase organic spinach production in Florida.