PROBLEM TO BE SOLVED: To provide an extremely lightweight ridging material having continuous water repellency preventing effect and excellent in preservability.SOLUTION: A method for producing the ridging material comprises adding a powdery product of clay minerals of zeolite and bentonite, a binder becoming insoluble by heating and comprising e.g. polyvinyl alcohol and starch, and water to a water-repellent organic material of a lightweight material with bulk specific gravity of &ge0.25 such as peat moss, mixing the product, and heating and drying the product at an initial temperature of 70°C-150°C to bring water content to &le10 wt.%. As a result, the clay minerals adhere to the surface of the organic material to improve water-absorbing properties and continuously prevent water repellency.COPYRIGHT: (C)2006,JPO&NCIPI【課題】持続的な撥水防止効果があり、保存性に優れ、且つ超軽量の培土資材を提供する。【解決手段】ピートモス等の嵩比重が0.25以下の軽量資材である撥水性有機資材に、ゼオライト、ベントナイトの粘土鉱物の粉状物、加熱により不溶化するポリビニルアルコールやでんぷん等からなるバインダー及び水を加え、混合し、水分10重量%以下となるまで品温70℃以上150℃以下の温度で加熱乾燥する。これにより粘土鉱物が有機資材の表面に付着し、吸水性を向上させ、持続的に撥水を防止する。
