ISHS Acta Horticulturae 51: Symposium on Protected Cultivation of Flowers and Vegetables
THE USE OF CALCAREOUS SAND IN ABU DHABI AS A GROWING MEDIUM IN THE SAND CULTURE SYSTEM |
| Authors: | Hamdy M. Eisa, Merle H. Jensen |
| Abstract:
The availability of power-water-food is essential for the development of desert seacoastal areas. Power is generated by the use of diesel engines. Water is desalinized through the use of excess heat from diesel engines. Food, vegetable crops, is grown in fiberglass plastic-covered greenhouses. To minimize the cost of importing conventional greenhouse growing media, indigenous sand in these areas is used as a growing medium. The sand contains over 90% calcium carbonate and is at a pH of 8.2. The sand lacks essential elements needed for vegetable production. Commercial-grade, water-soluble fertilizers containing all essential elements are dissolved in desalted water and piped to the greenhouses and onto plants through a trickle irrigation system. The pH of the nutrient solution is 5.6. Reaction between the acid solution and the alkaline sand results in the formation of calcium phosphate, which acts as a major precipitating and binding constituent. Further formation of calcium phosphate leads to binding and cementing of sand particles resulting in rock formation. Adjusting the pH of the nutrient solution to 6.6 decreased rock formation. The use of triple super phosphate mixed with the sand as a source of phosphorous did not result in rock formation, although vegetable crops differed in the response to this method of phosphorous fertilization. In spite of the rock formation, high yields of European greenhouse cucumbers, tomatoes, peppers and other vegetables are obtained. | |
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