Plants Without Soil

At an exhibit recently held in Taichung, what set most people abuzz was the exhibit from the Taiwan Fertilizer Company. What the firm had on display was not fertilizer, but deep green plants grown in water. Said one woman from the countryside, "You must be kidding! Plants grown in water!" "Is that enough?" asked one farmer, peering at the cabbage, his face a picture of disbelief. Three housewives clucked knowingly, "This is called clean vegetables, it's very popular. This way you could grow food at the South Pole or in outer space."

What they saw was amaranth and cabbage, with broad leaves and wide buds, of a fresh green color, rising out of a shiny black plastic box with a haughtiness that seemed to say, "Here I am!"

What is the world coming to when plants are not growing in the ground? The soil has always been the base of agriculture, respected and beloved by all farmers. Yet the effects of soil exhaustion, pollution, and urbanization have taken their toll, leaving the earth with less farmland, lacking its original fertility. This factor and modem man's distaste for dirt have made more people willing to forgo using soil in agriculture.

Scientists have been looking into this matter for some time. As early as the 17th century, they pondered ways of substituting for the three essential elements of agriculture: soil, water, and air. In 1956 English scientist Salmm-Hormer found a method where sand could replace soil. Four years later German botanists Sachs and Knop grew plants in water, and the effect of these experiments set other scientists thinking that if plant nutrients could be made to reproduce, then soil could be dispensed with.

Most flowers sold at florist shops are plants grown without soil. Material such as vermiculite is used to replace Mother Earth. It is germ-free and can hold considerable amounts of water and oxygen, requiring only the addition of nutrients to grow.

Of the 16 elements needed for plants to grow, only three, carbon, hydrogen, and oxygen are found in water and in the air, with the rest available in soil with low salinity. In theory, the lack of only one should make cultivation impossible, but scientists have discovered only six are essential, being carbon, phosphorous, potassium, calcium, magnesium, and sulphur. These elements are combined into a nutrient solution, which is then added to water. The composition of the nutrient solution varies from plant to plant.

Soil-less cultivation can be divided into water culture (hydroponics), gravel culture, and sand culture, but all require water, yielding the general name hydroponics. In 1969, the Provincial Lungt'an Senior Vocational Agricultural School began to develop gravel culture. Plants began life in a gravel bed, and then were transferred to flower beds, then greenhouses, and finally to farms. The school has been using this method quietly for sixteen years. Originally this technique was employed due to high waters, which left plant roots rotten, but now it is used with an eye toward good food. As the biggest hydroponics farm in Taiwan, they sell their produce every day in the markets of Taoyuan.

Other laboratories are developing this science, but none quite with the success of the Fengshan Tropical Horticultural Experiment Station. Their wax apples can be found in markets everywhere, but authorities are still deciding whether or not they are ready for large-scale marketing. Many problems, such as the humidity and salinity of the nutrient solution, still remain to be solved. The wax apple success is viewed as a happy accident.

The great majority of Taiwan's watermelons, available from January through August, are grown in river beds. Such an environment, with its mild temperature and ample moisture and oxygen, is ideal for raising watermelons. One drawback, however, is that it leaves them prey to disease and unable to reproduce. Originally the scientists at Fengshan were looking for a method to grow watermelons in the greenhouse. The large and sweet melons from the river came as a pleasant surprise.

At Fengshan the seeds are first placed in the nutrient solution and then covered with styrofoam. The stalks then begin protruding though holes in the water, and nutrient solution is pumped into the holes of the container. Oxygen also passes through these holes, allowing the plant to breathe. After the stalks have grown to where they require support, workers affix bags with straw rope to the stalk, making the watermelons appear as if they are climbing a tree.

Fengshan also has a "rock field." Water bearing nutrient solution is pumped into a trough lying below the plants, many of which are wax apples. The success of this soil-less cultivation has inspired many other laboratories in southern Taiwan to try their hand at hydroponics.

Plant roots grown through water culture are usually longer, faster-growing, and finer than those grown in the soil. One papaya grown by the Chung Hsing University Horticulture Department had roots 50 centimeters long, or nearly the size of a papaya tree. In addition, such roots need not fear sickness. They grow twice as fast as soil-grown plants, making them less apt to spread disease. Lettuce, for example, normally needs 40 days to reach maturity but with water culture, the time is cut to less than three weeks.

Soil-less cultivation requires greenhouse construction, with walls of a net-like material and a glass roof. Summers in Taiwan are humid and should the sunlight pass through the greenhouse, without being dissipated, the combination of heat and humidity can cause plants in soil to stop growing if not kill them.

Water culture does not have this difficulty. Tomato plants, thirty feet from root to bud, have been grown, a feat considered impossible in the past. The nearer the buds came to the roof, the greater was the heat, and their growth slowed accordingly. Keeping the humidity at reasonable levels served to give the plants a chance.

At present there is actually no reason not to use the soil. Soil-less cultivation demands a greenhouse, watering equipment, and plant beds. Expenses can run from NT$50,000 to NT$200,000 (US$1,250-$5000). Soil cultivation, by contrast, is inexpensive and simple. Plants without soil are perhaps most suitable for areas of famine, polar regions, and aboard ships at sea. Nevertheless, the public response to food grown on these farms continues to be positive. Should it ever replace the hard-working farmer in the field, his pants rolled up under a burning sun, it would mark a profound revolution in agriculture.

[Picture Caption]

Farmers at the Taichung exhibit view amaranth grown in water.

This method is particularly suitable for rooftop farming. At the Provincial Taichung Senior Vocational Agricultural School, styrofoam substitutes for soil.

Lifting up the plastic cover makes it easier to understand hydroponics.

"I'm twenty-five, but after 14 days this papaya is already more than half my size."

Plants can also be grown in sponges. Above are lettuce sprouts.

Is this melon plant wearing a wedding ring? No, the rubber band only signifies that this plant has pollinated.

This student is not taking their temperature, only checking the oxygen content of the water.

The plant is real but the dirt is artificial. In this pot, plants can breathe, photosynthesize, go without water, and still grow.

Look carefully. These chrysanthemum were grown in these vertical pollulators. (Photo courtesy of Chuan Tso-chuang)

Needing a warm, protective home in which to grow, greenhouse plants havethe lights turned on well before twilight.

This method is particularly suitable for rooftop farming. At the Provincial Taichung Senior Vocational Agricultural School, styrofoam substitutes for soil.

Lifting up the plastic cover makes it easier to understand hydroponics.

Plants can also be grown in sponges. Above are lettuce sprouts.

"I'm twenty-five, but after 14 days this papaya is already more than half my size.".

This student is not taking their temperature, only checking the oxygen content of the water.

Is this melon plant wearing a wedding ring? No, the rubber band only signifies that this plant has pollinated.

Look carefully. These chrysanthemum were grown in these vertical pollulators. （Photo courtesy of Chuan Tso-chuang）

The plant is real but the dirt is artificial. In this pot, plants can breathe, photosynthesize, go without water, and still grow.

Needing a warm, protective home in which to grow, greenhouse plants have　the lights turned on well before twilight.