HYDROPONICS or SOILLESS GARDENING

A scientific method of growing plants without soil. In the original method, a tank of concrete or metal is constructed, size according to need or space available, but of a depth of only 8 in. The water, which has minerals in solution, occupies half the depth, and across its surface is stretched a wire-mesh net on which rests a bed of vegetable litter with sawdust or peat merely for the purpose of giving a hold for the upper parts of the roots. Thus supported, the root grows down into the culture liquid from which it draws sustenance. In this way a continuous food supply is provided, which can be adjusted in strength and constituents to suit the needs of any particular group during each stage of development. The minerals dissolved in the water include phosphates, nitrates, sulphates, calcium and other special elements, and can be regularly renewed and regulated as to strength with a scientific accuracy which produces astonishing results, whether seed is sown in the litter belt, or the start is made from seedlings. The advantages claimed are: (1) during the whole period of development a plant has all the food it can absorb; (2) plants can be grown close together as enough food is always available; (3) there is relative freedom from weeds and disease infection; (4) the culture medium never ‘sours’ as does soil. Experiments with tomatoes have shown that the yield is so great as to equal 1750 tons per acre, and a tank one-hundreth of an acre in superficial area yielded 1480 lb. of potatoes. Flowers grown in this way have shown similar precocity.

The latest technique is to grow the plants by aggregate culture, I.e. the tank, bed or box is filled with a rooting medium such as sand or vermiculite (termed the aggregate) and this is then flooded or fed with nutrient solution. Amateurs can feed by means of a watering can. It will be appreciated first, that, by this system water takes the place of soil as the vehicle of growth and, secondly, it follows that as plants vary in their needs the containers must contain components to satisfy each, or a series of containers be used for plant groups having similar requirements. Some flourish in limy places, others in sand or gravel, others again in peaty soils, from all of which the extractable foods can hardly be the same. If the needs for the perfect development of each plant are known they can be more effectively met by growing the plant in a nutrient solution containing certain appropriate chemicals than in the soil where constant changes are in progress. In effect the liquid becomes a nutrient solution and, provided the aeration needed by all plant roots is assured, the result should be perfect. As growth proceeds, the chemicals will gradually be absorbed by the roots and eventually exhausted, so they need renewal from time to time. As a commercial adventure the future of hydroponics is well worth watching. The system was first experimented with on a wide scale in California where it yielded an extraordinary abundance of croppage, thus establishing its value as a new method of intensive production.

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