Organic hydroponics: A US reality challenging the traditional concept of “organic” and “soilless” cultivation

The continued growth of the US organic food market is capturing the interest of many growers and entrepreneurs producing and marketing specialty crops, including those investing in “soilless” cultivation systems (SCS). The high demand for and consequent high value of certified organic produce makes it compelling to invest in organic systems, including those employing hydroponic technology. These systems are considered hybrid cultivation systems in which organic-derived nutrient solutions and/or growing media are used to feed crops grown in SCS. Unlike in other countries, the US Department of Agriculture (USDA) National Organic Program (NOP) allows certification of “organic” crops produced in hydroponic, aquaponic, and aeroponic systems that are compliant with the US Organic Regulations. The organic certification of such hybrid system is supported by the USDA Agricultural Marketing Service, although in 2016, the Hydroponic and Aquaponic Task Force of the National Organic Standards Board (NOSB) examined the alignment of “organic hydroponic” or “bioponic” systems with the USDA organic regulations and recommended that aeroponic systems be excluded from organic certification. Today, while certified organic farms adopting bioponic systems are a reality in the US, there is still significant controversy concerning their alignment with the traditional organic concept. Traditional organic growers contest that it is not possible to produce healthy food without a healthy soil; on the other hand, organic hydroponic proponents claim that their cultivation procedures are compliant with the USDA organic regulation and that, not only they are producing healthy, organic crops, but their cultivation systems are also more sustainable than traditional soil-based organic production systems. While providing a brief overview of the subject and of the concept of bioponic systems adopted in the US, the objectives of this work are to: i) examine the challenges and potential opportunities offered by bioponic systems in comparison to both traditional organic and SCS, and ii) identify current knowledge-gaps and research priorities, so that future research-based knowledge may contribute to clarify the parameters that define each system.