Hydroponics and aquaponics are gaining traction in the local food movement, but their sustainability is being called into question. Each system along with its specific parameters and constraints should be examined before making a judgment.

Hydroponics is growing plants without soil. Aquaponics is combining hydroponics with aquaculture or fish farming. This results in a system where fish are grown in tanks. That water along with the waste the fish produce circulates through the hydroponic system and fertilizes the plants.

This is similar to farmers spreading cow manure on their fields to improve fertility. The water leaves the hydroponic system cleaner than when it entered and is pumped back to the fish tank. The plants are fertilized and the fish get clean water it’s pretty exciting.

These farms do not require soil, so growing food is possible in all kinds of new places, particularly urban areas. Where real estate is hard to come by, aquaponic farms in greenhouses can easily be put on rooftops, barges and refurbished shipping containers. This is excellent for cities that have heavily contaminated soils a common concern in rust belt cities, like Syracuse.

Bringing fresh produce to urban environments has the potential to alleviate food deserts in neighborhoods where access to fresh food is limited or nonexistent. Regardless, urban agriculture minimizes shipping costs and all of the associated carbon dioxide emissions and fossil fuel consumption.

Some hydroponic systems are indoors with artificial lighting. Artificial lighting requires electricity, yes, but consider it within the context of the system. How much energy does the lighting consume? How does the energy use on this farm compare to the amount of energy required to grow the same amount of produce in a more traditional system (think tractors, applying fertilizer/pesticides, mechanical harvesting, irrigation, transportation and refrigeration)?

Where is the energy coming from, the electrical grid or from renewable sources? It becomes a matter of how the numbers shake out. It would be curious to see how the price of hydroponically grown lettuce in Central New York in January compares to that same head of lettuce grown conventionally California.

The nutritional value of hydroponic or aquaponic produce also varies depending on the choices made in each system design. Hydroponic produce can be grown with fertilizers that deliver nitrogen, phosphorus and potassium, but none of the other nutrients essential for healthy plant growth. Hydroponic produce can also be grown using more well-rounded fertilizers including zinc, copper, magnesium and all of the other essential micro and macronutrients.

For aquaponics, it’s another story: No chemical fertilizers are used. The plants are fertilized with fish waste that may be supplemented with a few additional nutrients, but some systems don’t require any nutritional supplements at all. Many aquaponic systems feed fish commercial pellets, but experiments are being conducted feeding them post-consumer food waste.

Dare to dig deeper before dismissing the nutritional value of hydroponic produce.

In the grand scheme of things using hydroponics and aquaponics for urban agriculture is new technology that requires further development. The potential exists to push the boundaries of where agriculture can take place, what resources are required and who has access to good food. That alone is worth exploring.

Leanna Mulvihill is a senior forest engineering major and environmental writing and rhetoric minor. Her column appears every Tuesday. She can be reached at lpmulvih@syr.edu. 

Published on January 16, 2012 at 12:00 pm