Ring Culture, Some plants, notably tomatoes,and carnations, grow well in bottomless ‘ ’ standing on a bed of gravel or ashes. Real pots with the bottoms knocked out can be used but most ring culture is carried out in special rings made of bitumenised cardboard or ‘whale-hide’. Rings 9 inches in diameter and 9 inches deep are suitable for strong-growing plants. They are filled with ordinary soil and are stood on a bed of clean washed gravel or well-weathered boiler ashes at least 6 inches deep. The plants are raised in the normal way from or and are planted in the rings while still quite small. After planting they are well watered in so that the soil in the ‘rings’ is moist throughout. Subsequently all water is applied to the gravel or ash base from which it is drawn up into the soil by capillary attraction. Any solid or liquid food required is applied to the soil in the rings from which the plants derive all the chemicals they require.
The plants make two quite distinctsystems, one of fine in the soil, the other much coarser, moisture-gathering roots, in the aggregate base. At the end of the season the plants and roots are removed (they come easily out of the aggregate), the soil is discarded, to be replaced by fresh soil the following year, and the aggregate is flushed with water, perhaps with the addition of a little disinfectant such as formalin.
Straw Bale Culture. A method of growing tomatoes, cucumbers and possibly some other plants in greenhouses on decomposing straw bales. Wheat straw is the best, although barley straw can be used. Oat straw is too soft. Soil in theshould be level and covered with sheets of polythene film to isolate the straw from possible soil-borne infection. When placed in end to end the bales, well bound with wire, should be thoroughly soaked in stages, so that the water is completely absorbed, applying about 9 gals. per 4-cwt. bale in all over a period of three days.
Apply to each bale 14 lb. of Nitro-chalk and water in well. Give two more dressings at intervals of three days, of 1 lb. and lb. respectively,in each. To this last application of Nitro-chalk add 18 oz. of nitrate of potash and 4 oz. of sulphate of magnesium. Maintain a minimum temperature of 50° F. Decomposition will result and when the temperature falls below 100° F., planting can take place into a shallow bed (2 or 3 in. deep) of JIP.2 spread on top of the bales.
Cultivation is the same as for tomatoes or cucumbers in soil beds, except that heavyis necessary at first, preferably with a liquid fertilizer. The bales will decompose slowly during the season and it will be necessary to loosen and readjust the supports for the plants to prevent their roots being pulled out as the straw sinks.