應用不同製備條件之纖維素水膠改良砂質與森林土壤保水性之探討

The Improvement of Water Retention in Sandy and Forest Soils by Different Cellulose-based Hydrogels

植物保水劑在土壤中能將雨水或灌溉用水儲存吸收，具有吸水、儲水、保水的功能。纖維素衍生物製備水膠（Hydrogel）乾燥後製備乾膠（Xerogel），於混合後具有將水分保留於土壤之保水劑特性。本研究利用甲基纖維素（Methyl cellulose, MC）及羧甲基纖維素鈉（Sodium carboxymethyl cellulose, NaCMC）製備水膠，其中MC加入硫酸鉀製備具有室溫溫度敏感性纖維素水膠，NaCMC加入聚乙二醇二縮水甘油醚（Polyethylene glycol diglycidyl ether, PEGDE）製作具有化學交聯結構纖維素水膠，探討其於對於砂土（Sandy soil）及森林土壤之保水性質之影響。由實驗結果得知，添加水膠可提升砂土容水量13%以上，保水力可延長8天以上，且容水量與保水力隨添加量之水膠增加而上升；添加水膠於惠蓀林場土壤亦能有效延長土壤保水力。兩種水膠土壤保水力以添加MC基質水膠之效果較佳。本研究結果顯示纖維素基質水膠具有做為植物保水劑的潛力。 Soil conditioner can absorb and retain rain water in the soil by slow releasing water and reducing water loss. Hydrogels that derived from cellulose derivatives can be transformed into xerogels by drying in the oven and applied as soil conditioners. In this study, hydrogels derived from methylcellulose (MC) and Sodium carboxymethyl cellulose (NaCMC) were used. The temperature-responsive hydrogel was prepared by blending MC with potassium sulfate (K2SO4) to modify the hydrophobic interaction and infl uences the gelation at room temperature. The NaCMC based hydrogels was crosslinked by polyethylene glycol diglycidyl ether (PEGDE). The results indicated that increasing the dosage of hydrogels increased the water-holding capacity of sandy soil. Sandy soil treated with hydrogel signifi cantly improved the waterholding capacities by 13% and the water-retention time by 8 days. Water-retention capacities of forest soil was also signifi cantly improved. The MC based temperature-responsive hydrogel showed a better waterretention capacity than the NaCMC based hydrogels for both soil types. Our results suggested that the cellulose-based hydrogels have high potential to be applied as soil conditioners.