Growing plants in karst areas tends to be difficult due to the easy loss of water and soil. To enhance soil agglomeration, water retention, and soil fertility, this study developed a physically and chemically crosslinked hydrogel prepared from quaternary ammonium guar gum and humic acid. The results showed that non-covalent dynamic bonds between the two components delayed humic acid release into the soil, with a release rate of only 35 % after 240 h. The presence of four hydrophilic groups (quaternary ammonium, hydroxyl, carboxyl, and carbonyl) in the hydrogel more than doubled the soil's water retention capacity. The interaction between hydrogel and soil minerals (especially carbonate and silica) promoted hydrogel-soil and soil‑carbonate adhesion, and the adhesion strength between soil particles was enhanced by 650 %. Moreover, compared with direct fertilization, this degradable hydrogel not only increased the germination rate (100 %) and growth status of mung beans but also reduced the negative effects of excessive fertilization on plant roots. The study provides an eco-friendly, low-cost, and intelligent system for soil improvement in karst areas. It further proves the considerable application potential of hydrogels in agriculture.

中文翻译：

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具有控制释放腐植酸的超吸水性季铵瓜尔胶水凝胶，用于土壤改良和植物生长

喀斯特地区的植物生长很困难，因为水和土壤容易流失。为了增强土壤团聚性、保水性和土壤肥力，本研究开发了一种由季铵瓜尔胶和腐殖酸制备的物理和化学交联水凝胶。结果表明，两种组分之间的非共价动态键延迟了腐殖酸向土壤中的释放，240小时后释放率仅为35%。水凝胶中四个亲水基团（季铵、羟基、羧基和羰基）的存在使土壤的保水能力增加了一倍以上。水凝胶与土壤矿物质（特别是碳酸盐和二氧化硅）之间的相互作用促进了水凝胶-土壤和土壤-碳酸盐的粘附，土壤颗粒之间的粘附强度增强了650%。而且，与直接施肥相比，这种可降解水凝胶不仅提高了绿豆的发芽率（100%）和生长状况，还减少了过度施肥对植物根系的负面影响。该研究为喀斯特地区土壤改良提供了一种生态友好、低成本、智能化的系统。进一步证明了水凝胶在农业中的巨大应用潜力。