基于膨润土的保水型缓释肥料的制备及其缓释机制研究

Based on the problem of drought, less rain and low fertilizer efficacy in Xinjiang region, so in order to simultaneously achieve farmland water conservation and improve fertilizer utilization efficacy in the arid and semi-arid areas. On the previous research basis of preparation of super absorbent material based on bentonite, based on the urea and nitrogen phosphorus and potassium compound fertilizer as model fertilizers in the project, the slow release fertilizers with water retention based on bentonite/poly (acrylic acid - acrylamide) were synthesized by inverse suspension polymerization water. Through the study of the effect law of slow-release fertilizer preparation process parameters on structural composition and release properties, the preparation structure-activity relationship of slow release fertilizer and the regulatory mechanism of water retention and nutrient release properties of the slow-release fertilizer with water retention were established. Through simulated conditions of drought soil and natural rainfall, the law water retention and nutrients release of two slow release fertilizers with water-retention under different pH, temperature, water vapor pressure, salt concentration and other environmental factors; to establish nutrient diffusion behavior and the release dynamic model and clarify the nutrients release mechanism of the slow release fertilizer. The potted and plot experiments by carried out with cotton as the object of the study, the interaction effects of nutrient released and crop fertilizer efficiency were clarified,further optimize nutrient release mode to suitable for crop growth needs of Xinjiang region. Thus, this is to establish theoretical foundation and provide technical support for developing the efficient slow release fertilizer with water retention application in Xinjing region.

针对新疆地区干旱少雨、化肥肥效低下等问题，为同时实现干旱、半干旱地区农田节水、提高肥料利用率的目的。在前期基于膨润土的高吸水材料制备的研究基础上，项目以尿素和氮磷钾复合肥为模型肥料，拟开展基于膨润土/聚（丙烯酸-丙烯酰胺）的保水型缓释肥料及其保水缓释机制的研究。通过研究缓释肥料制备过程参数对其结构组成与缓释性能的影响规律，揭示保水型缓释肥的制-构-效关系，建立保水型缓释肥料的保水及养分缓释性能的调控机制；通过模拟干旱土壤和自然降雨条件下，研究两种保水型缓释肥料在不同pH、温度、水蒸气压和盐分浓度等环境因素下的保水及养分缓释规律，建立养分的扩散行为与释放动力学模型，阐明保水型缓释肥料的养分缓释机制。以棉花为研究对象进行盆栽及小区试验，阐明养分缓释与作物产生肥效的互作效应，进而优化养分释放模式以适宜于新疆区域的作物生长需求。为开发适合干旱半干旱地区应用的保水型缓释肥奠定理论基础和提供技术支持。

以膨润土为基质，尿素、氯化铵为肥源，海藻酸钠、丙烯酸、丙烯酰胺、 2-丙烯酰胺-2-甲基丙磺酸、聚乙烯吡咯烷酮以及棉花秸秆为原料，制备了四种具有吸水保水和养分缓释功能的保水型缓释氮肥，对产品的结构进行了表征，并系统地研究了产品的吸水保水和缓释性能以及对棉花的促生效果。主要结论如下：.1、以丙烯酸、丙烯酰胺、膨润土、尿素为原料，制备了一种含氮 14.98%的保水型缓释氮肥。该产品具有较好的吸水保水性、耐盐性以及缓释性。产品的吸水率与缓释性能与外界因素关系密切。产品的吸水率随着盐溶液浓度、离子电荷数以及离子半径的增大而减小，随着温度、 pH 的升高先增大后减小；产品释放速率随着离子浓度、离子电荷数、离子半径的增大而减小，随着温度、 pH 的升高而增大。.2、以海藻酸钠、丙烯酸、丙烯酰胺、膨润土、尿素为原料，制备了一种含氮 13.55%的保水型缓释氮肥。该产品具有较好的吸水性能及耐盐性，溶胀介质的离子种类及浓度、pH 都对产品的吸水率有影响；产品加入土壤后可以显著提高土壤的保水性；产品具有很好的缓释性能，在土壤中的 30 d 累积释放率为 56.1%；用该产品处理棉花种子可使其发芽率提高 18.32%以上。.3、以棉花秸秆、丙烯酸、聚乙烯吡咯烷酮、膨润土、尿素为原料，制备了一种含氮量为 18.11%且具有半互穿网络结构的保水型缓释氮肥。此产品在蒸馏水中的吸水率高达 1018.4 g/g，在 0.9 wt% NaCl 溶液中的吸水率高达 71.3 g/g，具有很好的吸水性及耐盐性；产品加入土壤后可以显著提高土壤的保水性能；产品在土壤中 30 d 的累积释放率为 60.8%，具有较好的缓释性能；产品在土壤中通过淋溶损失的氮含量仅为 10.3%，可以有效减少营养元素的流失；用该产品处理棉花种子可以使其发芽率，株高，根长，鲜重和干重分别显著提高 22.04%、 25.23%、 29.47%、 40.22%和 53.33%。.4、以棉花秸秆、丙烯酸、 2-丙烯酰胺-2-甲基丙磺酸、膨润土、负载 NH4+的生物炭为原料，制备了一种含氮量为 5.6%且具有保水性的生物炭基缓释氮肥。产品加入土壤后可以显著提高土壤的保水性能；该产品在土壤中 30 d 的累积释放率为 69.8%，通过淋溶损失的氮含量为 10.3%，迁移到土壤表面而损失的氮含量为 7.4%；用该产品处理棉花种子可以使其发芽率