|
Subsurface Textile Irrigation (SSTI) is a technology designed specifically for subsurface irrigation in all soil textures from desert sands to heavy clays. Use of SSTI will significantly reduce the usage of water, fertilizer and herbicide. It will lower on-going operational costs and, if maintained properly, will last for decades. By delivering water and nutrients directly to the root zone, plants are healthier and have a far greater yield. It is the only irrigation system that can safely use recycled water or treated water without expensive “polishing” treatment because water never reaches the surface. A typical subsurface textile irrigation system has an impermeable base layer (usually polyethylene or polypropylene), a drip line running along that base, a layer of geotextile on top of the drip line and, finally, a narrow impermeable layer on top of the geotextile (see diagram). Unlike standard drip irrigation, the spacing of emitters in the drip pipe is not critical as the geotextile moves the water along the fabric up to 2m from the dripper. SSTI is installed 15–20 cm below the surface for residential/commercial applications and 30–50 cm for agricultural applications. ==How SSTI Works== The systems rely on specific geotextiles to absorb the water from the drippers and to rapidly transport that water via mass flow and capillary action along the geotextile effectively turning those single drippers into billions of emitters. In essence, this enables intimate control of the speed of water delivery so that the capillary action of any soil can be matched (something that is virtually impossible for any other irrigation method including bare drip pipe below the surface). If the capillary action of the soil can be matched with the water delivery, only the minimal amount of water is needed to service the needs of the plants above (note that capillary forces draw water up from the water source to the roots of the plants). To increase effectiveness, SSTI products should have an impermeable base layer to slow gravitational loss of water and to create an elliptical wetting pattern under the soil surface (see diagram). It should also have a small impermeable top layer to ensure that water from the dripper does not “tunnel” through the geotextile and up to the surface (again a common problem with bare subsurface drip pipe). The effect of these two layers is dramatic as it maximizes the spread of water through the geotextile (up to 10,000 times faster than a clay loam soil as tested by Charles Sturt University). When comparing SSTI with surface drip, using the same amount of water, SSTI can cover 2.5 times the volume of soil and takes six times longer to dry down until the next irrigation is required 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Subsurface textile irrigation」の詳細全文を読む スポンサード リンク
|