| 摘要 |
<p>Method and apparatus are disclosed for controlling the relative humidity of a soil environment at a pre-set value using an enclosed volume (106) of a water-soluble or water-swellable material (114), said enclosed volume separated from the external environment by a relatively stiff and strong semipermeable membrane (104) and separated from a pressurized irrigation water supply by a water-impermeable constrictable flexible section (108) or diaphragm in the supply line (36, 38). 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 soil. When the soil moisture falls below the pre-set value, egress of water from the water-swellable material releases the constricting force on the flexible section thereby allowing increased flow of water through the flexible section of supply line to the soil. </p> |
