An Ageless Garden for Everyone
By Peggy Bradley
In the ancient homes of Maya Indians in Central America, seasonal drenching rains and flooding caused the native people to develop a growing platform, or table, to grow vegetables and medicinal herbs. These wooden tables were built about a meter above ground and then the box interior was filled with organic composted material. Sometimes a cover of braided reeds was woven into a type of shade cloth. Even today, traditional Mayan families still grow herbs and vegetables in these ancient growing containers.
Today those table growers have been reinvented into a simplified hydroponic grower that can help a family produce high quality vegetables. This becomes an important technology for people in marginal economic circumstances, making less than a dollar a day.
A 10 m2 Simplified Hydroponic Garden
A first simplified hydroponic garden that can help produce food for a family is about 10 square yards or 10 square meters. This garden will take about a week to build, and should last for about three years before needing repair or replacement.
The estimated cost to build a 10m2 garden is about $70. The materials vary from country to country and in most cases the garden is made of used shipping pallets that cost $2 each or $20 for the whole garden.
During the year the garden production ranges from 1.2 to 4.5 pounds of food a day. The garden requires from five to 10 gallons of water every day, an ounce and a half of nutrient, and about one hour of labor. The cost of food produced depends upon the cost of the fertilizers used, but is estimated at about two to three cents a day.
In commercial hydroponics, where the climate is controlled for the plants, ranges of productivity are 20 kilos per m2 per year (44 pounds) to 56 kilos per m2 per year (123 pounds), so the estimate of garden produce is within the estimates of commercial production.
The garden becomes productive when the technology has been effectively transferred. When the technology is understood and followed, the garden owner keeps the garden in high productivity, all tables full of actively growing plants, insects controlled, transplants ready to go into the garden.
Actual pound yields are also dependent upon what foods are grown, how much of the plant is not edible, or not used for food, and the water content of the foods. Lettuce, cucumber and tomato have a higher pound or kilo yield compared to carrots, onions and potatoes.
What can be expected from the garden owners is a statistical bell curve of yields, with some garden owners producing 3.36 pounds a day and others only 1.2 pounds. There will be those who produce even less, and give up on their gardens.
The primary reason for abandoning a garden is lack of technical support when there is trouble. When a garden owner cannot control a disease or insect they can quickly lose the entire garden. When transplants are not kept in production the garden sits idle until the transplants are produced.
The successful garden will be the one where the family takes care, is diligent in controlling insects, and exercises preventative care with yellow sticky cards and garlic sprays. If the garden is neglected it will be mostly unproductive or a failure.
The amount of fertilizer used in hydroponics should be able to produce from 50 to 100 times the amount of fresh vegetables, so the 1.5 ounces of hydroponic nutrient could produce from as much as nine pounds of food each day. Each garden owner has problems to work out in the beginning, and a normal yield for a new garden owner is expected to be about two pounds of food a day.
The simplified hydroponic garden can make a real difference in the quality of life for a family on a limited food budget. Table 1 shows a possible design of a 10 m2 garden that can produce more than four pounds of food a day.
Value of the Food Produced
The garden produce provides enough food to provide a small salad and daily vegetables for a family of four. The garden can be increased in size to provide more food for the family. Usually, only those who have successful gardens will want to expand.
In USA and Canada, the price of vegetables is going up, and many vegetables grown in the garden sell for $2 to $3 per pound. That makes the possible garden yield about $4 to $13.50 per day in grocery savings.
Over a year’s time, the garden will require about 35 pounds of hydroponic nutrients at a cost of about $40 to $70. That means a garden can produce from $1460 to $3650 per year in garden produce value. There are additional costs if there is water cost, and seeds need to be purchased if they are not harvested from the garden.
When compared to vegetables purchased in the local market, the simplified hydroponic produce should be of higher quality if the technology has been used effectively.
As a technology, pesticides and herbicides are never used on the garden. All insect control is from prevention and from organic sprays such as soap and milk. That means none of the vegetables should have any residual pesticides or herbicides, and therefore they should have a higher market value for being pesticide-free. This is not a guarantee from the market vegetables that might be grown with pesticide and herbicide control.
Because the garden vegetables grown with a properly mixed nutrient have full nutrition, including trace minerals, the vegetables should be of high quality with high values of vitamins A and C. These should also be at maximums because the vegetables are fresh picked as they are eaten.
The availability of fresh vegetables on demand also means the family will have vegetables when needed without needing any refrigeration, or going to the market. This can aid a family in reducing some of the labor required to produce and obtain food. If the foods had to be purchased in the local market they would need to be obtained and stored.
Obtaining Water
for the Garden
The ancient Maya lived in the Cancun in the Yucatan area of Mexico. They obtained water for their drinking water and gardens by gathering rainwater from their thatched roofs and then carrying water from a nearby cenote or underground pools. Another advantage of the table grower is that water is retained in the grower rather than running through and down to the water table. In the extremely porous areas of the Yucatan, the table growers reduced the amount of water required for growing plants - an important reduction when water has to be carried every day.
The garden required a daily supply of water and this should be clean water. In many areas of the world, there is no available supply of clean water. In some places water is extremely restricted, with the worst case probably being Mexico City where some people have only about a liter, or quart, of water a day. In these cases water must be purchased, often as bottled water for about $2 for five gallons. Areas with polluted or restricted water must re-evaluate garden costs that can double with purchased water.
Where the water is polluted, a sand filter can be built to clean the water before it is used in the garden. However, it is not always possible to know just what the pollutants are in the water and so the sand filter may not be able to remove some contaminants. When the only source of water is suspect, nonedible crops such as flowers should be grown and exchanged for foods.
There is a worldwide effort to ensure that all people on earth have potable clean water. As wells are dug, or water purification built, each family should be able to obtain sufficient water to grow plants in the garden. Until that time the best source of clean water is often rainwater harvesting.
Rainwater Harvesting
Rainwater can be gathered for the garden production. In areas with sufficient rainfall, or about 300mm per year, tarps or roofs can be used to gather rainwater that can then be used for the garden. In an area of rainfall, every five days a 50 gallon barrel needs to be used for rainwater collection for the garden. For a safer supply, about three barrels are needed.
Shade Cloth
For the garden to produce food every day, the plants have to be in an environment protected from extreme weather, such as freezing temperatures or drenching rains. The garden can be protected by having a shelter built around it or protection on top of a grower such as a clear plastic roof. In tropical areas, freezing temperatures are not common, and so the primary need will be a shadecloth or clear plastic to protect from too much sun or extreme rains.
In hot or dry climates, a shade cloth over the plants can reduce daily water requirements by one half. A square meter unprotected garden might use a gallon of water daily, but only half a gallon if protected with shadecloth. Instead of requiring 10 gallons of water a day, the garden water use is reduced to five gallons.
Shade cloth costs about 14 cents a square foot, or about $14 per grower, perhaps $140 for the 10m2 garden. This cost is far too much for a beginning garden owner, but there are sources of recycled shade cloth. A rustic shade cloth can even be made by weaving reeds together to block out half of the sun. These have been used in Mexico with great success. The shade is built directly over the table bed grower.
Training Session
The gardens require some expertise to both build and operate. The common experience in transferring the technology is a three-day training session, or about 15 hours of instruction and hands on practical training. After training the garden owners usually need technical support, or visits to the garden about six times throughout the year by a person with experience in the operation of the gardens.
In past experience with projects throughout the world (now over 16 countries) the first instruction and building of the first demonstration garden requires an expert in the technology.
Adapting the Technology
- Each country has different assets regarding materials that can be used to build growers and to use as growing substrates. So the basic components of the technology needs to be adapted to local conditions and materials. While a mix of red volcanic rock and rice hulls as a substrate might be easily obtained in Colombia, in Senegal these materials are not that common, so the substrate can be changed to sand mixed with sawdust, and peanut shells.
- Plant testing - Each area has a culture that affects the people’s preferences for foods. While many people in poverty are subsisting on a simple carbohydrate such as rice or corn meal, there are preferences for vegetables to be eaten with the staple food or as separate dishes. Even a family has preferences for foods that affect what they would buy or wish to grow.
- Growers - Some areas have a lot of discarded shipping pallets or other materials that can be recycled into growers for the plants. In other areas bamboo is readily available and can be grown or harvested for making growers. In areas of recent disaster, there may be recycled lumber or building materials that can be used for building growers.
The simplified hydroponic garden is now being used in 16 countries to help families end poverty and hunger. Currently the Sri Lanka Institute of Simplified Hydroponics, along with International ISH is preparing to help the refugees of the December 26, 2004 tsunami begin to grow their own food. Donations to help this effort are being accepted online at www.carbon.org.
About the Author: Peggy Bradley is the owner of Bradley Hydroponics located in Corvallis, Oregon. The company has an internet site at www.hydrogarden.com.