Preparation and properties of a coated slow-release and water-retention biuret phosphoramide fertilizer with superabsorbent

In this investigation, a novel water-insoluble slow-release fertilizer, biuret polyphosphoramide (BPAM), was formulated and synthesized from urea, phosphoric acid (H(3)PO(4)), and ferric oxide (Fe(2)O(3)). The structure of BPAM was characterized by Fourier transform infrared (FTIR) spectroscopy. Subsequently, a coated slow-release BPAM fertilizer with superabsorbent was prepared by ionic cross-linked carboxymethylchitosan (the core), acrylic acid, acrylamide, and active carbon (the coating). The variable influences on the water absorbency were investigated and optimized. Component analysis results showed that the coated slow-release BPAM contained 5.66% nitrogen and 11.7% phosphorus. The property of water retention, the behavior of slow release of phosphorus, and the capacity of adsorption of cations were evaluated, and the results revealed that the product not only had good slow-release property and excellent water retention capacity but also higher adsorption capacities of cations in saline soil.     

Preparation and properties of a double-coated slow-release and water-retention urea fertilizer

A double-coated, slow-release, and water-retention urea fertilizer (DSWU) was prepared by cross-linked poly(acrylic acid)-containing urea (PAAU) (the outer coating), polystyrene (PS) (the inner coating), and urea granule (the core). Elemental analysis results showed that the nitrogen content of the product was 33.6 wt %. The outer coating (PAAU) regulated the nitrogen release rate and protected the inner coating from damage. The slow-release property of the product was investigated in water and in soil. The possible mechanism of nitrogen release was proposed. The influences of PS coating percentage, temperature, water absorbency, and pH on the release of nitrogen were also investigated. It was found that PS coating percentage, temperature, and water absorbency had a significant influence on the release of nitrogen. However, the pH had no effect. The water-retention property of the product was also investigated. The results showed that the product not only had a good slow-release property but also excellent water-retention capacity, which could effectively improve the utilization of fertilizer and water resources. The results of the present work indicated that the DSWU would find good application in agriculture and horticulture, especially in drought-prone areas where the availability of water is insufficient.     

C36多元醇改良C18多元醇包膜肥料缓控释性能

为探讨C36多元醇(简称C36)对C18多元醇(简称C18,对照)包膜材料缓控释性能的影响,该文以C18为对照膜材,将C36与C18分别按照质量比1:2、2:3、1:1共混聚合制备成3种新型包膜材料,在相同工艺下依次制造成包膜厚度均为2.5%(膜材占核芯肥料的百分比)的包膜尿素,分别记作PCU1、PCU2、PCU3、PCU4,其中PCU1为对照。通过坠落撞击前、后包膜尿素的释放率评价C36作为包膜材料的效果。研究结果表明:C36与C18共混聚合包膜尿素的外观及耐撞击性能明显优于对照处理的,表现为包膜层光泽明亮、膜质均匀、膜层韧性好,同期静水培养的颗粒表面积较对照的增加了23%。该文提出了肥效期保持率(tR)的概念,并用其评价包膜肥料耐撞击性能。共混聚合物C36:C18比例为2:3时,包膜尿素耐撞击性能最优,受撞击后肥效期保持率tR可高达88%左右,为对照处理的2.5倍以上。该处理包膜尿素的初期溶出率、微分溶出率最小,与对照PCU1处理的无明显差异。C36嵌入C18共混聚合生成的新包膜材料对包膜尿素肥效期的影响与两者的比例和包膜材料的用量有关,当C36:C18为2:3,包膜材料用量(2.5%)小于常规用量(3%~4%)时,虽然包膜尿素的肥效期没有延长,但是包膜完整、膜层均匀、韧性强,在包膜肥受到强烈撞击的情况下能够很好地保持原有肥料的肥效期,即能保持包膜肥料的缓控释性能。因此,在C18多元醇嵌入适量C36多元醇是改良C18多元醇包膜材料,增加其包膜肥肥效期保持率的有效方法。     

三重耦合改性防止水基聚合物包膜肥料粘连并延缓释放

  【目的】  水基聚丙烯酸酯价格低廉、成膜性好,具有作为控释肥料包膜材料的潜力,但其玻璃转化温度低和耐水性差,导致用其制备的包膜控释肥料颗粒容易相互粘连并且养分释放过快。本研究旨在通过改性措施防止水基聚丙烯酸酯包膜控释肥料的粘连,并提升其控释性能。  【方法】  选用易获取且价格低廉的3种改性剂纳米二氧化硅、FeⅢ-单宁酸配合物和十六烷,通过简单的物理混合方式对水基聚丙烯酸酯进行耦合改性。采用动态热机械性能测定了改性前后包膜材料的玻璃转化温度和储能模量,采用接触角仪和水蒸气渗透装置分别测定了包膜的水接触角和水蒸气渗透率,采用静水溶出法测定了控释肥料的养分释放特征。为了更好地比较耦合改性的效果,将未改性的丙烯酸酯 (PA)、纳米二氧化硅单独改性的丙烯酸酯 (PA+Silica)、FeⅢ-单宁酸配合物单独改性的丙烯酸酯 (PA+Fe) 和十六烷单独改性的丙烯酸酯 (PA+HD)作为对照,分析了包膜材料性质改变对控释肥料养分释放特征的影响。  【结果】  耦合改性后包膜的玻璃转化温度提升了4.4℃,?70°C的储能模量提升了72.2%,水接触角提高了22°,水蒸气渗透率降低了13.6%。以上包膜材料性质的改变不但有效防止了控释肥料的粘连,也将其初期溶出率从未改性的38.29%降低到2.04%,控释期从未改性的8天延长到52天,释放模式也从和作物养分需求不匹配的“倒L”型变为和作物养分需求相匹配的“S”型。耦合改性改善包膜肥料粘连现象的原因为耦合改性将包膜材料的玻璃转化温度从20.40℃提升到了24.80℃。相关分析表明,包膜肥料初期溶出率的显著降低主要是因为FeⅢ-单宁酸配合物所降低的水蒸气渗透率和纳米二氧化硅所提高的玻璃转化温度和储能模量,而控释期的延长主要是由于十六烷所带来的水接触角的上升。  【结论】  采用纳米二氧化硅、FeⅢ-单宁酸配合物和十六烷耦合改性水基聚丙烯酸酯后,有效防止了控释肥料的粘连,显著提升了控释性能,并且该改性方式易于应用到工业生产中,是一种可行的水基聚合物包膜材料的改性方法。     

水肥调控技术及其功能性肥料研究进展

综述水肥调控的有关技术,以及以高吸水性树脂 (super absorbent polymer,SAP) 为保水、缓/控释材料制备保水型缓/控释肥料的研究进展,为今后此类肥料的开发、应用提供依据。水分和养分是限制我国旱地农业可持续发展的主要因子,以肥调水,以水促肥,充分发挥水肥的协同效应是提高水肥利用率的关键。目前,水肥调控 (耦合) 技术的实施主要通过农艺措施和施肥灌溉技术来完成。近年来,随着SAP性能的不断改善和使用的普及,人们对SAP在吸水保水的同时,对土壤肥料养分的保持和缓释作用开始给予了重视,以SAP为保水、缓释材料的保水型缓/控释肥料的研究成为水肥调控研究的热点。SAP与一般聚合物不同之处是它具有高度亲水性,聚合物的骨架是一个适度交联的网状结构,进入树脂分子内的养分离子或分子可以以各种结合形式被暂时固定而延缓了养分的释放。土壤中可溶性盐对SAP吸水性能有重要影响,但尿素分子影响甚小。保水型缓/控释肥料可通过养分负载、复混或包膜等工艺制备。保水型缓/控释肥料是水肥调控 (耦合) 技术、化学制剂保水节水技术和肥料缓/控释技术的综合运用和物化的载体,兼具吸水、保水和养分缓/控释功能,实现水肥在同一时空条件下的一体化调控,同时提高水分和肥料的利用效率,在农业、林业、环境修复、生态工程等领域具有广阔的应用前景。未来工作是进一步寻求合适的SAP制造原料和工艺,降低成本;应用分子设计,改善SAP的结构,提高生物降解性,控制盐分的不利影响,提高肥料的吸水、保水和对养分的缓释性能;加强养分释放机理和不同于普通缓/控释肥料评价方法的研究。     

改性玉米秸秆复合高吸水树脂的尿素吸收及缓释性能

为了提高化肥的利用率、降低环境污染和提高玉米秸秆的高附加值综合利用水平,以过硫酸铵和亚硫酸氢钠为氧化还原引发剂,将植酸改性玉米秸秆与衣康酸、乙烯基吡咯烷酮和丙烯酰胺接枝共聚制备植酸改性玉米秸秆复合高吸水性树脂（PCS-SA,phytic acid-modified corn stalk-composite superabsorbent）,该文重点研究了衣康酸与乙烯基吡咯烷酮质量比对PCS-SA尿素溶液吸肥速率、保肥率以及缓释速率的影响,采用扫描电镜（SEM,scanning electronic microscope）和傅里叶红外光谱（FTIR,fourier transform infrared spectroscopy）对PCS-SA的结构和形貌进行了表征。结果表明衣康酸与乙烯基吡咯烷酮质量比为70:30制备的PCS-SA对尿素吸附量为3.81 g/g,40 min尿素溶液吸肥率达到最大值（360 g/g）,PCS-SA吸肥凝胶去离子水中3 d尿素释放率为66.14%,在土壤中5 d尿素释放率为47.6%,明显降低了尿素的释放速率、提高了土壤的保肥能力。FTIR谱图初步证实PCS-SA的结构,SEM表明PCS-SA具有不规则的凹凸波状表面,并伴有许多大微孔和小毛细孔。该研究为PCS-SA在农林等领域的应用提供试验依据和参考。     

超微细磷矿粉包膜缓释肥的缓释特征及其对大白菜生理特性的影响

以超微细磷矿粉为主要膜材料对普通复合肥(N-P2O5-K2O:15-15-15)进行包膜,制备了超微细磷矿粉分别占膜材料质量0%、40%、50%和60%比例的4种包膜缓释肥料,分别为CRF2、CRF3、CRF4、CRF5。通过室内养分缓释性能试验和大田试验研究了超微细磷矿粉包膜肥养分缓释特征及其对大白菜生理特性的影响。结果表明:1)用日产JEM-1200EX型电镜扫描观察膜形态结构,4种比例的超微细磷矿粉包膜复合肥随膜材中超细磷矿粉比例的增加其膜壳表面均匀度和致密度增强,对养分释放的缓释能力逐步增强,但缓释效果较树脂包膜肥略差。4种自制包膜肥的养分释放期较普通复合肥延长58～68d,但低于释放期为88天的树脂包膜肥。4种自制包膜肥在土壤培养试验中的土壤氮素表观释放率与树脂膜接近。2)与普通复合肥相比,4种自制包膜肥,能不同程度提高大白菜中后期叶绿素含量、净光合速率(Pn)、蒸腾速率(E)等,提高结球期根系活力及叶片的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)等酶的活性。同时,大白菜单株的结球质量增加0.17～0.77㎏,产量提高6.66%～35.50%,提高了收获期大白菜的含糖量、糖酸比以及维生素C(VC)含量;3)与树脂包膜复合肥相比,各项生理指标均无显著差异。4种自制包膜肥的缓释性能及改善大白菜生理特性的顺序均为:CRF5≈CRF4>CRF3>CRF2。     

Nutrient Release Characteristics of Coated Fertilizers by Superfine Phosphate Rock Powder and its Effects on Physiological Traits of Chinese Cabbage

Four kinds of slow release fertilizers were prepared out by coating common compound fertilizer [nitrogen (N)-phosphorus pentoxide (P₂O₅)-potassum oxide (K₂O):15-15-15] with four kinds of superfine phosphate rock powder (SPRP) which accounting for 60% of the total coated materials in mass. Electronic microscope scanning, static water releasing test, soil incubation experiment, and a field experiment were conducted on their nutrient release mechanisms and their effects on physiologic traits of Chinese cabbage. The results showed that all these four kinds of SPRP could markedly improve microstructure and thus release rate. However, their capacity was inferior to controlled release fertilizer (CRF). The four homemade fertilizers increased chlorophyll content, photosynthetic rate, and transpiration rate in the leaves of Chinese cabbage during its late growth stage, and improve the superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) enzyme activities during its ball period. In addition, the four homemade fertilizers improved yield by 20.62%～33.41% and 18.94%～24.44%, respectively, over the common compound fertilizer during 2009 and 2010, and improved sugar-acid and soluble sugar and V_C contents of the head of Chinese cabbage at the harvest stage. There are not obvious differences of physiological traits between the J2 coated CCF fertilizer (JCRF2), Y2 coated CCF fertilizer (YCRF2), and Resin coated CCF fertilizer (CRF). Nutrient release characters and agricultural effect of four homemade fertilizers follow the order: JCRF2≈YCRF2>JCRF1≈YCRF1.     

水溶性高分子材料肥料包膜与缓控释性能研究

以亲水基团-COOH改性后的水溶性聚氨酯溶液为包膜材料,用转鼓包衣工艺制备包膜肥料。选择土柱淋溶法和土壤培养法对包膜肥料进行评价表明:水性聚氨酯在喷涂到肥料表面后能发生交联反应,去除其亲水性,成膜性良好。包膜后肥料比未包膜肥料,在释放性质上大大改善,可以有效控制养分的释放,包膜量为6%时较为理想。     

改性聚丙烯酸酯包膜控释肥料的控释性能研究

针对应用流化床包衣设备进行水溶性高分子聚合物包膜肥料中试生产中存在的问题,研究了交联剂用量对膜材料表面结构与疏水性能的影响,以及不同后处理工艺对改善包膜肥料控释性能的作用。结果表明,以水溶性高分子聚丙烯酸乳液为主成分的包膜材料中添加交联剂(氮丙啶)的比例由1%(质量百分数,下同)增加至2%,肥料包膜表面结构变得更加平整致密,疏水性能也有所增强,控释效果显著提升。在40℃静水浸泡的9 d时间内前者释放了90%以上的养分,而后者仅释放了约40%的养分。不同后处理工艺对增强包膜肥料的控释性能作用不一。烘箱加热的效果远好于微波处理,且当交联剂添加比例较低(0.3%)时,在一定范围内(60℃~80℃)升高后处理温度,包膜肥料的控释性能显著增强。而当交联剂添加比例增至1%以上时,升温对其控释性能几乎无影响。     

Fertilization impacts on green leafy vegetables supplied with slow release nitrogen fertilizers

Conventional over-fertilization in green leafy vegetables has promoted the need for alternative nitrogen management practices. A novel slow-release fertilizer, coated with inorganic minerals, was developed in our lab. The membrane structural characteristics and nitrogen release profile of the product were systematically studied. Furthermore, different fertilization treatments were prepared to study the potential nitrogen use efficiency in Brassica chinensis L., cultivated under open field and greenhouse cultivation patterns. With a relatively smooth surface, coating layer of the newly developed fertilizer stacked by bonded multi-layer of polyaryl polymethylene isocyanate was formed by tightly arraying solid phosphate rock powder granules. After immersing the fertilizer in water, there was about 13% nitrogen released after 24 h and 30% of nitrogen released in 7 days. Moreover, the fertilizer significantly enhanced the yield of Brassica chinensis L. by 28.2%. Nitrogen use efficiency of vegetables treated with the fertilizer was much higher than that of conventional fertilization.     

Slow-release urea fertilizer from sulfur,gypsum, and starch-coated formulations

To address nitrogen (N)-related environmental pollution, development of an economical, slow-release urea fertilizer is the need of the hour. A study was conducted on the reduction of nitrogen released from granular urea fertilizer by applying sulfur, gypsum, bentonite, and starch as coating material. Paraffin wax was used as a binder. The dissolution rates were studied by changing the composition of coating mixture using high-performance liquid chromatography. SEM was used to study the morphology of coated urea in terms of smoothness and uniformity. The ultraviolet spectroscopy analysis further authenticated the release behavior of coated urea in terms of nitrogen concentration. Coating material reduced the release rate of nitrogen from urea fertilizer, significantly. Mixture of sulfur and gypsum coating on urea gave slowest release rate of nitrogen from urea fertilizer, i.e., 37%, as compared to uncoated urea and thus seems to be the most promising binding material for product development.     

EFFECTS OF CONVENTIONAL AND CONTROLLED RELEASE PHOSPHORUS FERTILIZER ON CROP EMERGENCE AND GROWTH RESPONSE UNDER CONTROLLED ENVIRONMENT CONDITIONS

A series of experiments on the effects of form and rate of seed row placed phosphorus (P) fertilizer were carried out under controlled environment conditions using flats of a P-deficient Brown Chernozemic soil from Saskatchewan, Canada. The experiments were conducted in the laboratory and growth chamber using rates of seed row placed granular P fertilizer up to 100 kg P₂O₅ ha^?1. Two forms of monoammonium phosphate fertilizer were compared: 1) conventional MAP granules and 2) controlled release phosphorus (CRP) fertilizer granules (Agrium Inc, Denver, CO, USA.) made with a polymer coating to slow the release of phosphate to soil solution. Six crops were utilized in the study to provide a range of commonly grown cereal, oilseed, pulse and forage crops in Western Canada: wheat (Triticum aestivum), canola (Brassica napus), mustard (Brassica juncea), flax (Linum usitatissimum), yellow pea (Pisum sativum) and alfalfa (Medicago sativum). Parameters measured were percentage of planted seeds that had emerged after two weeks, plant biomass yield, and plant P uptake after four weeks. Most of the crops tested showed no negative impact on emergence with seed row placed conventional P fertilizer at rates up to ～20 to 30 kg P₂O₅ ha^?1. Pea, flax and mustard tended to be most sensitive to injury from high rates of seed placed MAP while wheat was least sensitive. The controlled release phosphorus fertilizer (CRP) product greatly increased the tolerance of crops to high rates of seed row placed P, with rates of 80 kg P₂O₅ ha^?1 placed in the seed row producing no significant injury for most crops. This effect is attributed to the coating reducing the harmful salt effect that occurs when high rates of fertilizer are placed in the seed row in close proximity to the seed. Generally, a rate of 30 kg P₂O₅ ha^?1 was sufficient to produce maximum early season biomass yield and P uptake for both conventional MAP and CRP fertilizers. Large differences in early P availability were not evident between the conventional P and controlled released P fertilizer products.     

基于水基反应成膜技术的聚合物包膜肥料的研制

以3种水基硅丙乳液(SD-528、SD-5281和GA-1710)为材料,利用水基反应成膜技术对这3种材料进行化学改性,制备了聚合物包膜肥料模型膜;研究了模型膜的养分扩散性能,在此基础上研制了水基聚合物包膜肥料;测定了包膜肥料养分释放曲线,并利用红外光声光谱对聚合物膜进行原位表征.结果表明,通过化学交联改性,硅丙基模型膜具有优良的成膜性和扩散性能,不同的乳液对包膜尿素的缓释效果影响显著;GA-1710和SD-528的缓释效果较好,在静态水中的释放时间可达到30 d,而SD-5281缓释性能较差,需要做进一步的化学改性;不同的乳液类型制备的包膜尿素的释放模式也不同,GA-1710累积释放曲线为"S"型,而SD-528为"L"型.因此,利用反应成膜技术,硅丙乳液在水基包膜肥料的研制中具有广阔的应用前景.     

Synthesis and characterization of zinc-coated urea fertilizer

The research was focused on the synthesis and characterization of zinc (Zn)-coated urea fertilizer. Zinc oxide (ZnO) particles were coated on urea granules through two different coating techniques, i.e., slurry coating and wet coating, and the release rate of the coated Zn was measured up to 24 hours. Slurry coating technique showed better Zn release rate and morphology of coated urea granules as compared with wet coating technique using different binders, i.e., water, molasses, paraffin oil, and the combined mixture of honey bee wax and gum arabica. Urea granules synthesized through wet coating technique have a low amount of Zn as compared with slurry-coated urea granules. Urea granules coated through slurry coating technique and molasses, paraffin oil, and water (MPW) as a binder were the best in term of coating efficiency, uniform size distribution of ZnO-coated particles, granule's morphology, and release rate of Zn from coated formulations.     

黄土旱塬长期施肥对小麦连作土壤养分和水分的影响

利用长期定位实验,在黄土高原旱地研究不同施肥下小麦连作22年后土壤养分及水分的变化状况,为合理利用水肥资源提供参考.在对照(CK)、单施氮肥(N)、单施磷肥(P)、单施有机肥(M)、氮磷化肥配施(NP)、氮磷化肥与有机肥配施( NPM)6个不同长期施肥处理中,测定耕层(0～20 cm)土壤的基础养分和土壤剖面(0～30...     

不同粒径生物炭包膜尿素缓释肥性能及缓释效果

为探究生物炭粉包膜处理对尿素缓释效果的影响,该研究以不同粒径稻壳生物炭粉为包膜材料,对尿素颗粒进行不同层数包膜处理,分别制备了3种生物炭包膜尿素缓释肥C_1（0.15 mm生物炭粉包膜）、C_2（内层0.15 mm,外层0.25 mm生物炭粉包膜）和C_3（内层0.15 mm,中层0.25 mm,外层0.425 mm生物炭粉包膜）,并对生物炭包膜尿素缓释肥性能及缓释效果进行了分析研究。研究结果表明3种生物炭包膜缓释肥粒径主要分布在2.90～4.80 mm,随着包膜层数的增加,包膜缓释肥粒径随之增大,C_2和C_3粒径显著高于C_1(P<0.05)。C_1、C_2和C_3的抗压强度为20.40～48.00 N,满足工业生产需求。与C_1和C_2相比,C_3颗粒表面较光滑,切面具有致密且孔隙结构丰富的层状结构,吸水倍率最小（1.69）,耐水性也显著优于C_1与C_2(P<0.05),氮元素缓释效果优于C_1与C_2。综上可以看出,3层包膜尿素缓释肥膜壳强度高于单层和双层包膜尿素缓释肥,通过控制不同膜层生物炭的孔隙结构和孔径,减缓水分的渗入及养分的流出过程,缓释效果突出,为生物炭包膜缓释肥的开发应用提供一个新技术路径。     

施用绿肥条件下减施化肥对土壤养分及持水供水能力的影响

以长期定位试验为基础,设置7个紫云英和化肥施用配比试验处理,以探索施用绿肥情况下减施化肥对土壤养分、持水和供水能力的影响。结果表明:在翻压紫云英条件下,即使不施化肥土壤氮也可基本得到满足,应适量施用化学钾肥,必须合理施用磷肥,以保证土壤全量和速效养分得到平衡和持续供给,化肥施用量减少未显著降低水稻产量;土壤持水、供水能力在处理间的趋势表现为:紫云英+40%化肥紫云英+60%化肥紫云英+80%化肥、紫云英+100%化肥单施100%化肥、单施紫云英CK,与CK相比,其它6个处理田间持水量提高了1.6%~15.4%,有效含水量增幅更大,平均提高1.5%~30.5%,说明紫云英化肥配施能显著提高土壤的持水、供水能力,且化肥施用量越少效果越好,而单施化肥或单施紫云英效果有限。因此,紫云英施用量一定时(22 500 kg/hm~2),化肥施用量应减少至40%甚至更低。     

几种包膜缓控释肥粒养分释放特征的研究

采用水浸泡法对国内外4种包膜控释肥料的养分释放特性进行了系统的研究。结果表明,4种缓控释肥料的初期溶出率均小于12%,微分溶出率在0.4%～1.5%之间,这符合国际上公认的缓/控释肥的评价标准,初期溶出率小于15%、微分溶出率在0.25%～2.5%之间。采用水浸泡法测定包膜控释肥料养分释放特征,简便快速,检测时间短,重复次数少,养分浓度变化直接反映出包膜控释肥料的释放速率特性,还可以定量的测定其供肥性能,控释肥料有控制养分释放、延长供应时间的作用;其中腐殖酸和炭基有利于提高肥料颗粒的水稳定性,减缓养分的释放速率。     

不同化肥品种对春小麦营养元素的吸收、土壤磷素的释放及其产量的影响

试验结果表明,不同处理的春小麦各生育期的氮磷吸收趋势是一致的.植株的氮素相对含量苗期最高,抽穗期最低,灌浆期逐渐提高,每个时期与对照几乎相同.而绝对含量各时期是逐渐上升的,且明显高于对照;植株磷素相对和绝对含量苗期最低,拔节期急速上升.不同处理的相对含量与对照接近,绝对含量明显高于对照;同时,合理施用氮肥,不仅能促进磷素的吸收,而且能促进土壤磷的释放,改变土壤磷的形态.通过F值测定,不同氮肥品种间产量差异不显著.氮磷配合处理间差异极显著.且以尿素和硫铵组合的处理增产效果最佳.同时,在人工灌溉条件下,施肥各