Water retention layer in soil composed of solidified natural rubber latexA greening system in which the water retaining layer is constructedAndRemove the topsoil of the siteExposure to expose ground soilSpraying of natural rubber latex on exposed soil surfaceSolidification process in which a natural rubber latex is solidified to form a water retaining layerThe method of making the above described greening system including the covering process to cover the topsoil removed on the water retaining layer.凝固した天然ゴムラテックスにより構成される土壌中水分の保水層、前記保水層が施工されてなる緑化システム、ならびに、施工対象地の表土を取り除き、地中土壌を露出させる露出工程、露出させた土壌表面に天然ゴムラテックスを散布する散布工程、天然ゴムラテックスを凝固させて保水層を形成させる凝固工程、保水層の上に取り除いた表土を被せる被覆工程を含む前記緑化システムの施工方法。