An Open Letter to Hani Sewilam, Fahad Kimera, Peter Nasr, & Mahmoud Dawood, and for the Broader Research Community

To: Drs. Hani Sewilam, Fahad Kimera, Peter Nasr, & Mahmoud Dawood, authors of “A sandponics comparative study investigating different sand media based integrated aqua vegeculture systems using desalinated water” (Scientific Reports, June 2022), and the Wider Research Community,

We are writing in a spirit of constructive dialogue and scientific accuracy to address significant misrepresentations and fundamental errors concerning the Integrated Aqua-Vegeculture System (iAVs) within your aforementioned publication. This letter also aims to serve as a cautionary note for the broader research community regarding the critical importance of accurate terminology and thorough literature review when investigating specialised agricultural systems.

It is important to preface our concerns by stating that an attempt was made to seek clarification on these matters previously in July 2022 with a detailed list of questions regarding the terminology, methodologies, and conclusions presented in your paper. While an initial indication was given that a response would be forthcoming, regrettably, no such clarification has been received to date (May 2025). Consequently, we feel compelled to address these issues publicly to encourage a necessary re-evaluation and to prevent the perpetuation of these errors in future research.

The primary issue stems from the conflation of iAVs with a generalized and often misunderstood concept of “sandponics,” coupled with an apparent oversight of foundational iAVs literature and a misapplication of its core operational principles.

Understanding the Integrated Aqua-Vegeculture System (iAVs)

The Integrated Aqua-Vegeculture System (iAVs) is a specifically defined, open-source food production methodology developed by Dr. Mark McMurtry and colleagues at North Carolina State University in the 1980s. It is an organically-conceived ecosystem that synergistically combines aquaculture (raising fish) with horticulture (growing plants in a sand medium). Key defining characteristics of iAVs include:

• The use of sand not only as a substrate for plant roots but, crucially, as a highly efficient mechanical and biological filter.
• Reliance on fish effluent (waste) as the sole source of nutrients for the plants.
• A specific system design that typically employs intermittent flood-and-drain irrigation of the sand beds, using simple, minimal plumbing, ensuring the entire water volume of the fish tank is regularly filtered.
• Distinct operational protocols, including specific fish feeding schedules designed to optimize nutrient processing and system health.

The Erroneous Conflation with “Sandponics”

While “sandponics” is a term that appears colloquially, often on social media, and sometimes as an incorrect synonym for iAVs, it does not describe the specific, scientifically documented iAVs methodology. If “sandponics” refers to any distinct system, it has been associated with trademarked approaches that may use sand as a medium but often involve hydroponic nutrient solutions rather than relying on integrated fish waste for plant nutrition. The only inherent similarity is the use of sand as a growth medium.

Specific Points of Concern in “A sandponics comparative study investigating different sand media based integrated aqua vegeculture systems using desalinated³ water”:

Your paper presents several statements and methodological choices that are incongruent with established iAVs principles and existing literature:

1. Incorrect Equivalency: The paper states: “On the other hand, sandponics (SP), which is also referred to as an Integrated Aqua-Vegeculture system (iAVs) is an aquaponic-related growing technique…”This assertion is fundamentally incorrect. iAVs is a distinct, well-defined system, not a interchangeable term or a mere subset of a vaguely defined “sandponics.” This initial misidentification inevitably leads to further inaccuracies.
2. Misinformation Regarding Existing Literature and System Limitations: The paper claims: “However, some limitations to the SP system need to be addressed. They include operators requiring specialized training, crop nutritional deficiencies due to insufficient fertilizers, finding suitable sand for crops that require cooler climates, and expensive heated systems.”These limitations are not characteristic of a properly designed and managed iAVs. iAVs was conceived for operational simplicity, and its nutrient cycling, when correctly managed, typically provides comprehensive plant nutrition. The citation provided for these limitations is a general review that itself appears to conflate distinct system types and does not accurately reflect iAVs capabilities as documented in primary source literature. Furthermore, the paper asserts: “Most importantly, very few works in the literature report the system’s functionality since it’s not yet a commonly practiced technique” and “There is very little or no scientific literature about growing crops in sandponics systems hence, creating so many questions related to the operation, functionality, optimization, sand suitability, and system productivity.”These statements strongly suggest a failure to conduct a thorough literature search specifically for “Integrated Aqua-Vegeculture System” or “iAVs.” A considerable body of work, pioneered by Dr. McMurtry, exists and explicitly details the operation, functionality, optimization, sand suitability, and productivity of iAVs.
3. Misguided Statement on Food Security: The paper suggests: “Relying solely on such farming systems to solve the food security issue may not be entirely sufficient.”While no single system is a panacea, this statement, made in the context of a mischaracterised system, cannot be fairly applied to iAVs without considering its documented successes, particularly in resource-limited contexts, which stem from its inherent water efficiency and organic nutrient cycling.
4. Description of an Irrigation Method Alien to iAVs: In the “Materials and Methods” section, your paper details an irrigation setup: “Plants were irrigated using manually punched diaphragm emitters, and the irrigation flow rate was controlled using small plastic valves at the start of every irrigation tube. Emitters were installed in drip tubing at a 30 cm distance as well the tubing lines were also placed 30 cm between each other.”This describes a drip irrigation system. This is not the irrigation methodology of an iAVs. True iAVs design employs a simple, robust flood-and-drain (or intermittent flow) mechanism where water from the fish tank floods the sand beds, percolates through the sand biofilter, and drains back to the fish component, typically via gravity. This process involves minimal, uncomplicated plumbing and expressly avoids drip emitters, which are prone to clogging with organic effluent.
5. Description of a Fish Feeding Protocol Inconsistent with iAVs Best Practice: The paper states: “The fish were fed 3–4 times daily…”The established best practice for iAVs involves feeding fish twice daily, with the crucial guideline that the final feeding occurs no later than 2:00 PM. This timing is strategic, ensuring the entire volume of the fish tank water is processed through the sand biofilter during daylight hours before the system’s biological activity reduces overnight. This optimizes water quality and nutrient availability.

Consequences of Misrepresentation

The discrepancies outlined above are significant. They indicate that the system configuration and management described in your paper, while involving fish and sand, did not align with the fundamental design or operational principles of an Integrated Aqua-Vegeculture System. Therefore, the conclusions drawn from your study cannot be reliably extrapolated to, or considered representative of, true iAVs performance or characteristics.

Such misrepresentations, even if unintentional, have detrimental consequences:

• They perpetuate confusion within the scientific community and among growers, policymakers, and the public, obscuring the unique attributes and benefits of iAVs.
• They can lead to flawed subsequent research if studies are designed based on incorrect premises about how iAVs operates.
• They risk misinforming potential adopters of sustainable agriculture technologies.
• They inadvertently discredit or overlook the decades of dedicated research that have gone into developing and documenting the iAVs methodology.

A Call for Accuracy and Diligence

We strongly urge you to revisit your paper’s underlying assumptions and consult the foundational literature on Integrated Aqua-Vegeculture Systems, particularly the work of Dr. Mark McMurtry and subsequent related research.

For the wider research community, this situation underscores the critical need for:

• Precise Terminology: Using correct, specific nomenclature for distinct agricultural systems.
• Thorough Literature Reviews: Ensuring that foundational and specialised literature for the specific system under investigation is consulted.
• Methodological Fidelity: When claiming to study a particular system (e.g., iAVs), ensuring the experimental setup and operational parameters accurately reflect that system’s established design.

We trust that this open letter will encourage a careful re-evaluation of the representation of iAVs in your work and will serve as a valuable point of reference for future research in this vital domain. Advancing sustainable agriculture effectively depends on building upon a clear, accurate, and well-documented body of scientific knowledge.

Sincerely,

Rita T. Pryce