坡缕石基复合高分子吸水保水缓释肥料研究

Droughts and low fertilizer use efficiency are the important factors that limit the agricultural production in the western region. The preliminary experiments show that the water retention slow-release fertilizer, which integrates slow-release fertilizer technology and superabsorbent resin, could efficiently improve the fertilizer use efficiency and water resource. This project will prepare a series of attapulgite-based water retention slow-release fertilizers with core-shell structure, of which the core are fertilizer nutrients by physical embedding and chemical bonding of nitrogen, phosphorus, potassium and other elements, the inner coatings are starch, cellulose, carrageenan and other natural polymers, and the outer coating material are superabsorbent resins. So, the water retention slow-release fertilizer has function of water absorption, water conversation, drought resistance and moisture conservation, it also enabled the nutrients release slowly. The performance was characterized by structural analysis, component analysis and surface observation. The water absorption rate and equilibrium water absorption ratio were determined, meanwhile, the slow release property was examined. The addition of attapulgite not only can reduce cost, but also improve the salt resistance. Furthermore, attapulgite contains a lot of nutrients, such as potassium, iron, magnesium and other nutrients, which are necessary trace elements for cropper growth and development. Thus, the attapulgite-based water retention slow-release fertilizer will provide theoretical and experimental basis for regulation technology of water to promote fertilizer and fertilizer to regulate water.

干旱缺水和肥料利用率低是制约西部地区农业生产的重要因素。前期实验表明，缓释肥料技术与高吸水性树脂复合一体化的吸水保水缓释肥料是提高肥料利用率、节水增效的重要技术。本项目将肥料元素氮、磷、钾等分别通过物理包埋和化学键合方法，制备出一系列以肥料元素为核、分别以变性淀粉、纤维素、卡拉胶等天然高分子为内包膜材料，以吸水性树脂为外包膜材料、同时复配坡楼石，既具有吸水保水、抗旱保墒功能，又能使肥料缓慢释放的具有核壳结构的坡缕石基复合高分子吸水保水缓释肥料。在性能测定方面进行结构分析、成份分析和表面观察，测定样品的吸水速度及平衡吸水率，考察样品在土中的缓释性。其中坡缕石的加入，不仅可以降低成本，增加高吸水性树脂的耐盐性，而且，在坡缕石中含有很多农作物生长发育所需的微量元素如钾、铁、镁等营养成分。因此，坡缕石基复合高分子吸水保水缓释肥料将为"以水促肥，以肥调水"的农业重要水、肥调控技术提供理论和实验依据。

我国用占世界7%的耕地养活了占世界22%的人口，肥料在保障国家粮食安全中发挥了重要作用。然而，由于长期的过度施肥不仅造成了巨大的资源浪费，而且也带来了许多环境污染问题。缓控释肥料能够有效控制养分释放速率，延长肥效期，可以最大限度地提高肥料利用率，减少养分流失造成的环境污染问题，提高施肥的经济效益，保障农产品品质，对农业可持续发展具有重大意义。本课题着眼于开发环境友好、可降解、成本低廉的多功能缓控释肥料，以无机矿物黏土坡缕石为基材，制备了三种坡缕石基复合高分子吸水保水缓释肥料：（1）通过原位接枝聚合反应，制备了一种新型的坡缕石基复合水凝胶。该多功能缓释肥料的氮含量为13.2%，具有较好的养分缓释性能。该多功能缓释氮肥制备方法简单、成本低廉、可降解，将坡缕石引入纳米复合材料制备中，不仅能够提高吸附剂的吸附性能，而且能够起到减缓肥料养分释放速率的作用；（2）将尿素和磷酸锌铵包埋于坡缕石中作为肥料内核，以醋酸丁酸纤维素作为内层包膜材料，以羧甲基壳聚糖-g-聚丙烯酸/坡缕石（CMCS-g-PAA/APT）保水剂作为外层包膜材料，制备了一种具有保水功能的包膜型缓释肥料；（3）以尿素和磷酸氢钙包埋于坡缕石中为肥料内核，以小麦秸秆/海藻酸钠共混物为内层包膜材料，以聚（丙烯酸-co-N-羟甲基丙烯酰胺）/小麦秸秆复合高吸水树脂为外层包膜材料，制备了一种双层包膜的保水性氮磷缓释肥料，肥料样品中氮（N）和磷（P2O5）的含量分别为20.6%和9.9%，具有较好的缓释性能。对三种多功能缓控释肥料的养分含量、在土壤中的养分缓控释效果、包膜材料的降解性、肥料对土壤保水能力的影响，以及改良土壤结构的功能等多方面进行了系统研究。