Hydroponics is a subset of hydroculture and is a method of growing plants using mineral nutrient solutions, in water, without soil.
The two main types of hydroponics are solution culture and medium culture. Solution culture does not use a solid medium for the roots, just the nutrient solution. The three main types of solution cultures are static solution culture, continuous-flow solution culture and aeroponics. The medium culture method has a solid medium for the roots and is named for the type of medium, e.g., sand culture, gravel culture, or rockwool culture.
There are two main variations for each medium, sub-irrigation and top irrigation[specify]. For all techniques, most hydroponic reservoirs are now built of plastic, but other materials have been used including concrete, glass, metal, vegetable solids, and wood. The containers should exclude light to prevent algae growth in the nutrient solution.
Our Vertical Growing system allows growers to grow crops hydroponically. Just fill the bags with coconut coir , hydroton or rock wool and away you go. Our system is easily hooked up to an irrigation system that pumps synthetic chemicals to your plants.
Perhaps the best way to describe the difference between hydroponic growing and organic growing is through an article published by Eric Sideman, Ph.D. ........
In the late 1960s I watched a play by Megan Terry called Home: Or Future Soap on public television. The set was a single room that had no view of sky, ocean, sun, snow, hills or rivers. People lived their whole lives in this single room; never left their rooms; and those rooms were set on top of and beside more rooms. Rooms and rooms and rooms. Air, water and food were piped into each room, and waste was piped out. People did not think this was a bad way to live: Everyone lived like this, and it was all anyone knew.
The play had many messages, but the one that stuck with me is that we cannot judge what makes another person happy, or what is important to another person, or what one person thinks is good or bad. While some things are clearly bad, most can be good or bad depending on our opinions. Sunlight may be important to one person but a disturbing source of glare to someone else who just wants to read a book. Some people may be perfectly happy living their entire lives with eight other people in a single room, and the earth could support a much larger population if everyone wanted to live like that. But some of us highly value things that don't come in a room.
Hydroponics: Like Plants in Boxes
Like people living in boxes, hydroponics is a way of growing plants in an unnatural environment, using mineral solutions and no soil. Plants can be hung in solutions or grown in inert media with nutrient solutions passing through the media. Hydroponics works because plants need only 16 or 17 minerals in the correct proportions to grow. Of course, they need light, but they do not need soil.
In the 1600s, experiments with "water culture" of plants did not work, because not until much later did scientists discover which nutrients plants needed. But by the mid-1900s, soilless culture was working pretty well and was being promoted as capable of revolutionizing agriculture. Production could be maximized because crops had all the water they needed; oxygen was dissolved in the water, so a lack of oxygen never limited root growth and metabolism; mineral nutrients were present in just the correct proportions; and the relatively sterile system minimized disease and insect problems.
Today this system is called hydroponics. I have seen hydroponic production facilities where people suit up to enter the greenhouse as if they were going into an operating room in a hospital, and then harvest vast quantities of tomatoes that appear perfect. The production facilities most often work like the rooms in Megan Terry's play: All plant needs are delivered in bags, and waste leaves in a pipe.
Wikipedia relates a hydroponic success story on Wake Island in the Pacific in the 1930s. At its refueling site there, Pan American Airlines grew food without soil for passengers. Likewise, NASA is studying hydroponics as a way to feed people on Mars.
If humans ruin the soil on earth, then hydroponics will be very important. And if earth’s human population continues to grow as it is, all farmland may be occupied by rooms, as in Megan Terry's play, and soilless production will be essential.
The Organic Difference
As with hydroponics, the development of organic farming was all about supplying nutrients to plants. When the founders of organic farming and gardening saw the diminishing fertility of soils managed with chemical fertilizers, and the malnourished crops coming from those soils, they started thinking about how plants obtain mineral nutrients, and they recognized the need to replenish the soil with organic matter so that mineral nutrients could reliably be held in and recycled by the life of the soil.
Many books have been written about organic farming and gardening, but this art and science basically comes down to seeing organic growers as soil stewards – not just users – who are devoted to building and maintaining soil fertility (mineral content) and structure rather than feeding plants from a bag of minerals each season.
We have come to realize that soil is actually a system full of life and nutrients. Thousands of species live together, eating and dying and recycling minerals among themselves. The organic grower introduces crops to this system and tries to interfere with it as little as possible.
Of course, harvesting removes some minerals from the system, and those must be replaced. But organic growers minimize the loss of minerals from the system and recycle and conserve as much as possible. We depend on the whole living system of the soil to do this. Robert Rodale’s slogan, “Feed the soil, not the crop,” summarizes and contrasts organic production with hydroponic.
Hydroponic culture is not bad, it just is not organic. Organic is organic and differs from hydroponic (and conventional farming) primarily because organic soil management depends on the biology of the soil to decompose and recycle nutrients rather than on buying most of the plant nutrients from off the farm. Furthermore, in organic systems, even the nutrients bought in from off the farm are usually waste products (seed meals, fish meals, manures, etc.) being recycled by biological decomposition in the soil.
In contrast, hydroponic farming provides plants with readily available nutrients that are usually synthesized chemically. Even if they are natural sources of available nutrients being bought and fed, this misses the point of using the biology of the soil to feed the plant. It misses the point of organic.
As I learned from watching Megan Terry's play, I am in no position to label this good or bad, but it is not organic. Perfectly good plants can be grown using hydroponic methods, but hydroponic methods do nothing to care for the soil or conserve and recycle nutrients, which is the central theme of the practices that make a farming system organic.
In December 2001, the USDA published its Rule governing practices on organic farms. Before this, while the Rule was being written, the organic community worried that the USDA would create a rule that measures the organic nature of a product with a probe. Instead, the USDA recognized the true nature of organic growing – an organic soil – and wrote a Rule based on cultural practices rather than on products. Included are mandated practices that "…maintain or improve the physical, chemical, and biological condition of the soil." In fact, USDA’s very definition of organic production hits the nail on the head: " … [a] production system that … responds to site-specific conditions by integrating cultural, biological, and mechanical practices that foster cycling of resources, promote ecological balance, and conserve biodiversity.”
In contrast, hydroponic production systems eliminate ecological balance. Crops are produced nearly in the absence of other biology. Rather than fostering recycling of resources through cultural, biological and mechanical practices that promote ecological balance, hydroponic systems usually try to eliminate bacteria and fungi and basically buy in nutrients and discard waste. An organic production system works with the natural bacteria and fungi and biological processes in soils in a way that fosters cycling of resources and promotes ecological balance.
Hydroponics has its place and purpose, but it is not organic – although gray areas exist. A soilless mix could be made from compost and other recyclable materials and may meet the parameters of organic farming. Similarly, the Living Machine system that John Todd developed to recycle waste and grow fish and crops may be called hydroponic and it uses elements of organic agriculture.
A debate is going on right now in Washington, D.C., as the USDA National Organic Program and the National Organic Standards Board (NOSB) try to decide whether plants grown without soil can be called organic, and if so, which systems to allow and which to disallow. Based on a recommendation from the NOSB, I think they are going to get it right, and organic farmers will keep feeding the soil.
Eric Sideman is MOFGA’s organic crops specialist. You can address your questions to him at 568-4142 or firstname.lastname@example.org.