Understanding Organic Agriculture Through a Hydroponic Discussion

Andrew M. Hammermeister

First, my apologies for this lengthy treatise. I have pondered the interesting organic hydroponic discussion/debate for a while. Having studied soil science, I have a great attachment to soil and my first instinct is that soil-based production is the most ecologically consistent with organic, as would be suggested by our eminent pioneers of the movement.  

I then step back to take a broader perspective. If we had hydroponic technology at the onset of the movement, would it have been permitted as organic? Maybe not; maybe we would still be “grounded” in our soil base. But, in a similar line of thinking, would the pioneers of the movement imagined that we would have a sugar-laden carbonated beverage labelled as organic? Maybe not. 

When thinking about organic, I consider expected outcomes, which include:  

  • lower risk to farmer health,  
  • lower risk to rural communities and consumer health,  
  • ecological sustainability,  
  • viability for the farmer,  
  • reduced use of non-renewable and maybe renewable resources like water, and  
  • lower risk to the environment including less disturbance of the land base, lower nutrient losses and conservation of biodiversity.  

Hydroponic can contribute to all of these goals as well and could arguably achieve at least some of these goals more effectively. But is it natural? 


What is natural, anyway? 

I often hear the argument that terrestrial plants are not meant to grow in an aquatic environment. The soil itself consists of solid mineral particles and pore spaces occupied by water, air, and biology/organic matter. The solid mineral component of the soil is an important anchoring medium for plant roots. Soil minerals also slowly release nutrients into the soil solution that is drawn into the plants. At times, soils become saturated (i.e., the pore spaces fill almost completely with water), sometimes for extended periods of time. Many terrestrial plants are adapted to tolerate saturated (arguably aquatic?) conditions for extended periods, especially if there is good air exchange in the water. If the plant’s natural genetics allow the plant to grow in saturated conditions, then can we really argue that it is not natural?  

Enter the soil biology and nutrient uptake argument. It is clear that plants and soil microorganisms have a unique and not fully understood relationship. This relationship can be beneficial, neutral or antagonistic. This relationship is also expected to lead to highly nutritious foods. We expect our standards to guide a grower toward promoting beneficial soil biology. However, nutrient status of food is related to not only soil biology, but also to the inherent fertility provided by soil minerals. Soil mineralogy varies tremendously across the landscape, linked to geological history as well as management history. Frankly, some soils are inherently less fertile than others, making it difficult to predict or control a plant’s nutrient status.  

At the same time, hydroponic production has demonstrated that growing conditions can be controlled/managed to optimize targeted nutritional properties, and these controlled conditions may even present some nutritional advantages more consistently than soil-based systems. The question for hydroponic is whether the right traits are being targeted in the controlled/managed system. But this same problem exists in crop breeding programs. 

Plants also physiologically respond to many stressors in their environment, and moderate degrees of stress can produce some desirable qualities in plants as food. Hydroponic production is generally designed to eliminate, control or minimize these stresses. So, let’s compare with organic greenhouse container production. I am not an expert in this area, but it’s my understanding that the ‘soil’ medium is created by starting with largely sterile (to avoid introduction of diseases and pests) ingredients of mineral, organic matter (such as peat), and fertility sources. After this, an inoculant of “beneficial” soil biology is added to bring “life” to the soil. In essence, the soil has been ‘bio-engineered’ according to attributes that the grower has deemed appropriate.  

I have entered such organic greenhouses after first dressing in a bio-suit and stepping into disinfecting mats to ensure that pests are not introduced. I understand the need for protection, but it occurs to me that this growing environment can be very delicate—not robust as I might have expected. At the same time, the greenhouse has eliminated most sources of stress from pests and environment, and is controlling/recirculating waste. So, we have a manufactured growing medium designed to simulate soil in a closed, stress-‘managed’ environment. I wonder if this is really that different from hydroponic? Would the pioneers of organic have endorsed such greenhouse growing conditions?  

At the General Assembly of the International Federation of Organic Agriculture Movements (IFOAM), the movement has decided to accept aquaculture into the organic movement providing it is in a natural environment, but aquaculture in closed recirculation systems was not accepted. Similarly, our livestock standards require outdoor access. Is this consistent with our position on plant production? For hydroponic, yes; but what about closed container greenhouses? Is this a fair comparison? 


A Balancing Act 

Perhaps this all comes back to an exercise of discussing and debating more deeply what the movement stands for, and how we balance those principles with consumer expectation as well as market development.  

First, we must acknowledge that while some practices may achieve the same desired outcomes as organic, it does not mean that it is organic. Second, we must ensure that our organic practices are working toward not only achieving the principles, but also constantly improving our ability to achieve the expected outcomes of organic. Third, if we are applying logic (as opposed to philosophy) toward the acceptance of practices, we must be consistent. Fourth, for organic to have impact on global issues, it must grow quickly while still meeting consumer expectations about what it means to be organic. And lastly, organic should be modern and forward-thinking while still adhering to its principles; this may mean critical evaluation and perhaps acceptance new technologies/practices that were not available when the movement began. 

So, does this mean hydroponic should be accepted? The new IFOAM aquaculture position is consistent with not allowing hydroponic, but I still struggle with whether it is consistent with our acceptance of the closed system of container greenhouse production. Are consumers of organic rooted in soil as strongly as the movement? These are important questions that ultimately lead us to considering the movement and its principles more deeply.  

Help me decide! 



Andrew Hammermeister is the Director of the Organic Agriculture Centre of Canada and Associate Professor in the Department of Plant, Food and Environmental Sciences at Dalhousie University in Truro, Nova Scotia. He can be reached at Andrew.hammermeister@dal.ca.