Abstract: The invention aims at providing a pumice-based culture medium which shows outstanding characteristics as a culture medium to be used in protected horticulture. To this end, the invention provides a culture medium comprising particulate pumice having a saturated water permeability of 0.3-0.8 cm/sec and an air permeability of 15-40 cm/sec in both a dry sample and a wet sample. In another embodiment, the invention provides a culture medium having charcoal added to a culture medium comprising the particulate pumice having the above-described physical properties.

Abstract: A method and an apparatus for measuring the moisture content of the soil in order to enable pF value based control of irrigation in cultivation on the soil, as well as a method and an apparatus which use the first-mentioned method and apparatus to enable pF value based control of irrigation. To attain these objects, the invention provides a method for measuring the pF value (soil moisture tension) of the soil, comprising the steps of (a) preliminarily determining the correlation between pF value and volumetric water content of the soil to be measured, (b) measuring the volumetric water content of the soil, and (c) converting the value of the volumetric soil water content of the soil measured in the above step (b) to the corresponding pF value on the basis of the correlation between pF value and volumetric water content predetermined in the above step (a). Also a method and an apparatus for controlling the irrigation of the soil based on the measurement of the pF value by the method.

Abstract: The invention aims at providing a method and an apparatus for measuring the moisture content of the soil in order to enable pF value based control of irrigation in cultivation on the soil, as well as a method and an apparatus which use the first-mentioned method and apparatus to enable pF value based control of irrigation. To attain these objects, the invention provides a method for measuring the pF value (soil moisture tension) of the soil, comprising the steps of (a) preliminarily determining the correlation between pF value and volumetric water content of the soil to be measured, (b) measuring the volumetric water content of the soil, and (c) converting the value of the volumetric soil water content of the soil measured in the above step (b) to the corresponding pF value on the basis of the correlation between pF value and volumetric water content predetermined in the above step (a).

Abstract: A desalination apparatus and method utilizing solar energy provided with a solar heat collector for heating a heating medium with solar energy, a heat exchanger cooperating with an evaporation can so as to subject the heating medium and raw water in the evaporation can to heat exchange and generate water vapor therein, a condenser cooperating with a raw water tank so as to receive the vapor from the evaporation can, cool the vapor by subjecting the vapor and raw water in the raw water tank to heat exchange and obtain distilled water.