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硫包衣尿素氮素释放特性及其评价方法研究 总被引:1,自引:0,他引:1
采用静水释放法研究了38℃下6种不同硫包衣尿素氮素释放特性,并对不同硫包衣尿素的初期养分释放率、7d静态氮溶出率和微分溶出率进行了比较,探讨了硫包衣尿素氮素释放特性及其评价方法。结果表明,6种不同肥料的氮素释放曲线基本可分为"S"形、倒"L"形和直线形,其氮素累积释放率(质量分数)达到80%所需要的时间分别为48,85,32,80,41和23d;其氮素释放率与时间的关系可用抛物线扩散方程和一级动力学方程进行拟合,且效果较好;硫包衣尿素的初期养分释放率和7d静态溶出率可用于养分释放性能的综合评价。 相似文献
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《化肥工业》2017,(5)
以3种养分释放期不同的控释尿素为供试肥料,采用化工行业标准《控释肥料》(HG/T 4215—2011)中规定的25℃静水浸提凯氏定氮法和100℃快速浸提凯氏定氮法,试验研究了不同养分释放期控释尿素的不同掺混比例对养分释放特征的影响。试验结果表明:几种控释尿素掺混后养分释放率的实测值与按比例加权值计算的释放率相当,通过100℃静水浸提法也可快速预测掺混控释尿素在25℃静水中的养分释放期;不同养分释放期的控释尿素掺混后,其养分释放期仍与养分释放期较长的那种控释尿素相同,养分释放高峰点出现时间与不同养分释放期控释尿素掺混比例有关;根据不同养分释放期控释尿素时段溶出的养分加权值计算不同时段的养分释放率,所得预测值与实测释放率基本一致;对于掺混控释尿素,养分释放期较长的控释尿素掺混一定比例的养分释放期相对较短的控释尿素,可在作物前期或在作物快速生长期出现养分释放高峰,更好地满足作物养分最大效率期对养分的需求,弥补单一长效控释尿素前期养分供应不足的缺点,使控释肥养分释放与作物各生育期对养分的需求相同步。 相似文献
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硫包衣尿素,又称为涂硫尿素、包硫尿素或硫包尿素,英文名sulfur coated urea,简称SCU,外观为黄色球状颗粒,无机械杂质。硫包衣尿素兼顾缓释氮肥和硫肥的功效,通过在尿素外面包裹硫磺,聚合微晶蜡密封剂而制成的,是一种优良的可实现对氮的缓慢释放的新型缓控释氮肥。 相似文献
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采用蒸馏后滴定法和折射仪法测定了4种不同类型硫包衣尿素的初期养分释放率和静态氮溶出率,并进行了实验室比对工作,探讨了硫包衣尿素养分释放特征及国际标准制定所需的数据处理问题。结果表明:2种测定方法均可获得较好的精密度,并且无显著性差异,但折射仪法操作更便捷、快速,适合企业在线检测。实验室比对试验结果的精密度由ISO 5725—2∶1994测量方法与结果的准确度(正确度与精密度)的第2部分(确定标准测量方法重复性与再现性)获得,符合国际标准制定的要求。 相似文献
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以聚己内酯多元醇和异氰酸酯为包膜材料,制备了膜材用量为4%,6%和8%的聚己内酯基聚氨酯包膜尿素(PCU1、PCU2、PCU3),通过扫描电镜、恒温静水培法、胶园土壤培养法分析聚己内酯基聚氨酯包膜尿素膜层结构、养分释放速率以及释放期。结果表明,包膜尿素表面覆盖了聚己内酯基聚氨酯膜层,从而起到了物理阻隔作用,使包膜尿素具有较好的养分控释效果。随着膜材用量增加,包膜尿素释放期延长,PCU1、PCU2、PCU3在静水中的释放期分别为31.60,86.65,260.11 d。聚己内酯基聚氨酯包膜尿素在静水和胶园土壤中的养分释放特征曲线基本相同,培养介质不会改变聚己内酯基聚氨酯包膜尿素的养分释放模式,但胶园土壤培养显著缩短了PCU3的释放期,释放期仅为206.54 d,较静水中缩短了53.57 d。 相似文献
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Shuming Tao Jun Liu Kemo Jin Xiaoyun Qiu Yuan Zhang Xueqin Ren Shuwen Hu 《应用聚合物科学杂志》2011,120(4):2103-2111
Triple polymer coated with controlled‐release water retention fertilizer (TCWF) and enhanced mechanical property was developed by coating polyethylene (first layer), poly (acrylic acid‐co‐acrylamide) superabsorbent (second layer), and poly (butyl methacrylate) (third layer) consecutively on the granule core urea in the fluidized‐bed coater. The inner layer possessed controlled‐release property, the middle layer had water absorbent characteristic, and the thin outer layer aimed to protect the fragile layer of the superabsorbent. The relationship between the thickness of coating layer and the nutrient releasing properties was established. The effects of polymerization parameters on the water absorbency of the superabsorbent were studied and optimized as well. The nutrients release behaviors of this triple‐coated urea in both water and soil were investigated and compared. The results showed that TCWF not only performed as a good controlled‐release fertilizer but also had excellent water retention capacity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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Evaluation of the morphological and release characteristics of coated fertilizer granules produced in a Wurster fluidized bed 总被引:2,自引:0,他引:2
In the present study, coated fertilizer granules were produced in a Wurster chamber of a fluidized-bed equipment for controlled-release agrochemical applications. The coating material was a commercially available latex of poly(vinylidene-chloride). The influence of the process parameters (e.g., spray rate of the polymer latex, fluidization air velocity, distance of the partition from the air inlet and perforation percentage of the plate at the air inlet) on the morphology and quality of the coating was thoroughly investigated. The surface characteristics of the coated fertilizer granules were examined by scanning electron microscopy (SEM). The release rate of the fertilizer's nutrients from the coated granules was determined by kinetic-release experiments carried out in distilled water. Depending on the selected process conditions, the coating thickness could vary from 25 to 65 μm, while the surface of the coated granules changed from completely smooth to rough and porous. It was shown that by suitable selection of the coating conditions in the Wurster process, controlled-release fertilizers exhibiting prolonged release profiles could be produced. 相似文献
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缓/控释BB肥是我国缓/控释肥料的发展方向 总被引:8,自引:0,他引:8
分析了树脂和硫磺包裹尿素缓释肥料发展缓慢的原因和弊端,提出以水溶性聚合物作为尿素和复混肥料的包膜、胶结和内质缓释剂,具有降解快、对作物无害、改善土壤结构、成本低等特点,将促进缓释肥料的发展。采用生产不同时间段释放养分的缓释肥,按作物不同生育期对养分的需求比例掺混在一起,生产作物专用的缓/控释BB肥料简单易行,应是我国缓/控释肥料的发展方向。 相似文献
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聚氨酯包膜控释尿素制备工艺与养分释放特性研究 总被引:4,自引:0,他引:4
4,4'-二苯基甲烷二异氰酸酯(MDI)与植物油多元醇均匀喷涂在流化状态的尿素颗粒表面并发生化学反应,形成聚氨酯膜层。以侧喷流化床包膜工艺为基础,通过研究包膜量、反应温度、反应物比例等不同工艺条件下包膜尿素的养分释放性能,获得的生产聚氨酯包膜尿素的最佳工艺条件为反应温度75℃、MDI与植物油质量比1.0:1.0、反应时间20 min、催化剂用量0.40%(质量分数)、包膜比率为4.0%(质量分数),此包膜控释尿素的养分释放周期可达70 d。 相似文献
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Determining permeability of coatings of polymer-coated urea 总被引:10,自引:0,他引:10
Permeability of polymer coatings on urea varies greatly with the type of polymer. A conventional test of measuring the effectiveness of coating involves a 7d static dissolution rate of coated urea into concentrated urea solution, but the results are only qualitative. Our approach was, instead, to make quantitative measurements of permeability, and so make more accurate predictions of release rate of urea across a membrane. A simple device, consisting of a container attached to vertical pipes at the bottom, was constructed to determine permeability of coats on urea granules. A turbulent flow of water ran over a 2 cm pack of coated-urea granules so urea did not accumulate at the outer surface of the coated granules. Separate determinations with two thicknesses of coats (8.8 and 14.7µm) were conducted with water at 12 or 31°C. Permeability and activation energy of permeability were calculated. A comparison was also made between release rate of urea calculated from permeability and that determined by 7d dissolution rate method at 23°C. Nearly 100 h were required for 100% release with the thick coating, but only 20% urea was released after 168 h with the 7d dissolution rate method. 相似文献
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Asma Sofyane Mohammed Lahcini Abdellatif El Meziane Mehdi Khouloud Abdelmalek Dahchour Sylvain Caillol Mustapha Raihane 《Journal of the American Oil Chemists' Society》2020,97(7):751-763
In an effort to enhance the efficiency of fertilizer use and minimize their negative impact on the environment, a novel biomass-based, functional controlled-release fertilizer was used to improve nutrient use efficiency and increase crop production systems for more sustainable agriculture practices. Here, bio-based amino-oil (Priamine) mixtures were proposed as an outer coating with different layers for the control of phosphorus release from diammonium Phosphate (DAP). These hydrophobic coatings conferred excellent barrier properties and flexibility to coatings. The morphological characterization of the coated fertilizer was performed by scanning electronic microscopy (SEM), electronic diffraction X-ray (EDX) and mapping, and revealed the formation of a cohesive film and a good adhesion between DAP fertilizer and coating film. The release rate of nutrients (phosphate) in water was investigated by UV–Vis spectrophotometer. The effect of coating thickness was investigated on release time and diffusion coefficient of phosphor release in distilled water. Release time increased with the coating thickness. The diffusion coefficient of nutrient release decreased with the coating thickness. Compared with uncoated granule which is totally solubilized after less than 2 hours, the P release profiles of the coated granules reached the equilibrium stage approximately after 98 and 126 hours when the DAP is coated with only Priamine single-layer (1L) and double-layer (2L), respectively. Moreover, the strategy adopted has successfully provided a very slow release and long-term availability of nutrient sources with bio-based coating oil compared to uncoated fertilizer (DAP) and therefore exhibited promising application for sustainable development of modern agriculture and circular economic. 相似文献