To Your Health
When organic produce is not available or is too expensive, are those grown in water or in greenhouses less likely to be contaminated with pesticides?
When the produce is grown in water, or hydroponic cultivation, the requirements set for organically grown produce are very difficult to meet. The term "organic" is a matter of definition by a certifying agency, and the definition usually rules out the chemical fertilizers used in hydroponics. For instance, organic farming methods specifically call for fertilizers such as blood meal, bone meal, or fish meal to enrich the soil in which a plant is grown, all of which dissolve incompletely and are poorly suited for hydroponics. Hydroponics uses nutrients that are completely dissolved in water to grow plants without any soil at all.
Both cultivation techniques avoid the use of pesticides and herbicides. Organic farmers rely on crop rotation, animal and green manures, mechanical cultivation, and other biological methods to control insects, diseases, and weeds. Hydroponically grown produce is usually free of pesticide residues because it is grown indoors and can be said to be pesticide-free even though it does not meet the rather narrow definitions of organic farming.
Because the definition of organic farming usually includes a provision that the system be in place for some period of time, typically three years or more, in the past some certifying agencies allowed the use of a "transitional organic" label. This signified that a farmer was using organic methods but not long enough to reach the pesticide-free requirement. Since 2002 the USDA has not allowed this. Some organic advocates support a return to the transitional label, saying it can help farmers make the switch to organic methods and are asking the USDA to reconsider this portion of the labeling guidelines.
Use of the term "organic agriculture" is declining in favor of the term "sustainable agriculture," a term that applies to both organic and hydroponic cultivation methods. Organic farmers shun chemical fertilizers and any other products and practices that harm the earth, while hydroponics uses technologically advanced nutrient solutions and techniques that require no soil.
The advantage of hydroponics lies with its ability to directly provide crucial nutrients required for superior plant growth, a great benefit for people who don't have a lot of space to work with, on city rooftops for instance. Hydroponic growing materials can be recycled and can use less water than conventional methods, so more food can be produced using fewer resources. In the future, the line between the two methods will likely blur, and the ideal indoor garden as a fusion of hydroponics and organics will emerge.