Method for controlling the relative humidity in a soil environment and apparatus for accomplishing same

Abstract From the Canadian patent

Method and apparatus are disclosed for controlling the relative humidity of a soil environment at a pre-set value using an enclosed volume of a water-soluble or water-swellable material, said enclosed volume separated from the external environment by a relatively stiff and strong semipermeable membrane and separated from a pressurized irrigation water supply by a water-impermeable constrictable flexible section or diaphragm in the supply line. When the soil is more moist than the pre-set value, intake of water through the membrane causes expansion of the water-swellable material which in turn constricts the flexible section of the water supply line to interrupt the flow of water to the …