Equidistant combination wavelength screening and step-by-step phase-out method for the near-infrared spectroscopic analysis of serum urea nitrogen

We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve parameter selection with stability.A multiparameter optimization platform with Norris derivative filter-partial least squares(Norris-PLS)was developed to select the most suitable mode(d=2,s=33,g=15).Using equidistant combination PLS(EC-PLS)with four parameters(initial wavelength I,number of wavelengths N,number of wavelength gaps G and latent variables LV),we performed wavelength screening after eliminating high-absorption wavebands.The optimal EC-PLS parameters were I=1228 nm,N=26,G=16 and LV=12.The root-mean square error(SEP),correlation coefficient(R_(p))for prediction and ratio of performance-to-deviation(RPD)for validation were 1.03 mmol L^(-1),0.992 and 7.6,respectively.We proposed the wavelength step-by-step phase-out PLS(WSP-PLS)to remove redun-dant wavelengths in the top 100 EC-PLS models with improved prediction performance.The combination of 19 wavelengths was identifed as the optimal model for SUN.The SEP,Rp and RPD in validation were 1.01 mmol L^(-1),0.992 and 7.7,respectively.The prediction effect and wavelength complexity were better than those of EC-PIS.Our results showed that NIR spectroscopy combined with the EC-PLS and WSP-PLS methods enabled the high-precision analysis ofSUN.WSP-PLS is a secondary optimization method that can further optimize any wavelength moc odel obtained through other continuous or discrete strategies to establish a simple and better model.

Oligosaccharide and Creatine Supplementation on Glucose and Urea Nitrogen in Blood and Serum Creatine Kinase in Basketball Athletes

Summary： The effects of oligosaccharide and creatine （Cr） supplementation on glucose, lactic acid and urea nitrogen levels in blood and activity of serum creatine kinase （CK） were explored. Twenty CUBA male athletes were divided into 4 groups： group A （supplementation of Cr alone）, group B （supplementation of oligosaccharide）, group C （supplementation of oligosaccharide and Cr） and group D （placebo control group）. By using orthogonal L4 table （2a ）, the experiment was performed. There were factors including oligosaccharide （carbohydrate, CHO）, Cr and their correlation. Each factor had two levels： supplementation and no-supplementation. The results showed that the supplementation of CliO or Cr alone, combined supplementation of CHO and Cr could significantly reduce the glucose, urea nitrogen levels in blood and serum CK activity after competition in the athletes. Moreover, the effects of combined supplementation of CHO and Cr were more satisfactory. It was concluded that supplementation of CliO and Cr could promote the recovery of physical performance and athletic abilities after athletics in basketball athletes.

Patient characteristics with high or low blood urea nitrogen in upper gastrointestinal bleeding

AIM: To examine characteristics of patients with blood urea nitrogen(BUN) levels higher and lower than the normal limit.METHODS: Patient records between April 2011 and March 2014 were analyzed retrospectively. During this time, 3296 patients underwent upper endoscopy. In total, 50 male(69.2 ± 13.2 years) and 26 female(72.3 ± 10.2 years) patients were assessed. Patients were divided into two groups based on BUN levels: higher than the normal limit(21.0 mg/d L)(H) and lower thanthe normal limit(L). One-way analysis of variance was performed to reveal differences in the variables between the H and L groups. Fisher's exact test was used to compare the percentage of patients with gastric ulcer or gastric cancer in the H and L groups.RESULTS: White blood cell count was higher in the H group than in the L group(P = 0.0047). Hemoglobin level was lower in the H group than in the L group(P = 0.0307). Glycated hemoglobin was higher in the H group than in the L group(P = 0.0264). The percentage of patients with gastric ulcer was higher in the H group(P = 0.0002). The H group contained no patients with gastric cancer.CONCLUSION: Patients with BUN ≥ 21 mg/d L might have more severe upper gastrointestinal bleeding.

Global Optimization of Norris Derivative Filtering with Application for Near-Infrared Analysis of Serum Urea Nitrogen

Near-infrared (NIR) spectroscopy combined with chemometrics methods was applied to the rapid and reagent-free analysis of serum urea nitrogen (SUN). The mul-partitions modeling was performed to achieve parameter stability. A large-scale parameter cyclic and global optimization platform for Norris derivative filter (NDF) of three parameters (the derivative order: d, the number of smoothing points: s and the number of differential gaps: g) was developed with PLS regression. Meantime, the parameters’ adaptive analysis of NDF algorithm was also given, and achieved a significantly better modeling effect than one without spectral pre-processing. After eliminating the interference wavebands of saturated absorption, the modeling performance was further improved. In validation, the root mean square error (SEP), correlation coefficient (RP) for prediction and the ratio of performance to deviation (RPD) were 1.66 mmol?L-1, 0.966 and 4.7, respectively. The results showed that the high-precision analysis of SUN was feasibility based on NIR spectroscopy and Norris-PLS. The global optimization method of NDF is also expected to be applied to other analysis objects.

PREPARATION OF UREA NITROGEN ADSORBENT OF COMPLEX TYPE AND ADSORPTION CAPACITY OF UREA NITROGEN ONTO THE ADSORBENT

复杂类型的脲氮吸附物，在明胶膜(IE ) 由 chitosancoated 二醛纤维素(CDAC ) 和使不能调动的 urease 组成，被准备。纤维素，二醛纤维素(数模转换器) 和 CDAC 被扫描电子显微镜描绘。结果显示纤维素 C2-C3 契约在氧化 ofperiodate 下面被打破，它是到数模转换器的 oxidated。数模转换器与去乙酰壳多醣是涂的， CDAC 被获得。脲氮的吸附在间歇式系统被学习到在 Na_2HPO_4-NaH_2PO_4 缓冲液的吸附物上。实验参数的效果包括氧化 ofCDAC，起始的脲氮集中，酸碱值和温度的度，在脲氮的吸附能力上到在 CDAC/IE 重量比率 10 点的吸附物上：1 被调查。结果显示这些参数显著地影响了吸附能力。脲氮的吸附能力是在 CDAC 88 百分比的氧化的度的 36.7 mg/g 到吸附物上，起始的脲氮集中 600 mg/L，酸碱值 7.4 和温度 37 deg C。

Predictive Value of Serum Creatinine, Blood Urea Nitrogen,Uric Acid, and β2-Microglobulin in the Evaluation of Acute Kidney Injury after Orthotopic Liver Transplantation

Background：As a major complication after orthotopic liver transplantation （OLT）,the occurrence of acute kidney injury （AKI） is frequently defined by serum creatinine （Cr）;however,the accuracy of commonly used blood urea nitrogen （BUN）,uric acid （UA）,and β2-microglobulin （β2-MG） remains to be explored.This retrospective study compared the accuracy of these parameters for post-OLT AKI evaluation.Methods：Patients who underwent OLT in three centers between July 2003 and December 2013 were enrolled.The postoperative AKI group was diagnosed by the Kidney Disease Improving Global Outcomes （KDIGO） criteria and classified by stage.Measurement data were analyzed using the t-test or Wilcoxon rank-sum test;enumerated data were analyzed using the Chi-square test or Fisher＇s exact test.Diagnostic reliability and predictive accuracy were evaluated using receiver operating characteristic （ROC） curve analysis.Results：This study excluded 976 cases and analyzed 697 patients （578 men and 1 1 9 women）;the post-OLT AKI incidence was 0.409.Compared with the no-AKI group,the AKI group showed very significant differences in Model for End-stage Liver Disease score （14.74 ± 9.91 vs.11.07 ± 9.54,Z =5.404;P ＜ 0.001）,hepatic encephalopathy （45 [15.8％] vs.30 [7.3％],x2 =12.699;P ＜ 0.001）,hemofiltration （28 [9.8％] vs.0 [0.0％],x2 =42.171;P ＜ 0.001）,and 28-day mortality （23 [8.1％] vs.9 [2.2％],x2 13.323;P ＜0.001）.Moreover,mean values of Cr,BUN,UA,and β2-MG in the AKI group differed significantly at postoperative days 1,3,and 7 （all P ＜0.001）.ROC curve area was 0.847 of Cr for the detection of AKI Stage 1 （sensitivity 80.1％,specificity 75.7％,cutoffvalue 88.23 μmol/L）,0.916 for Stage 2 （sensitivity 87.6％,specificity 82.6％,cutoff value 99.9 μmol/L）,and 0.972 for Stage 3 （sensitivity 94.1％,specificity 88.2％,cutoff value 122.90 μmol/L）.Conclusion：The sensitivity and specificity of serum Cr might be a high-value indicator for the diagnosis and grading of post-OLT AKI.

The role of rumen epithelial urea transport proteins in urea nitrogen salvage:A review

The symbiotic relationship between the host and the rumen microbiome plays a crucial role in ruminant physiology.One of the most important processes enabling this relationship is urea nitrogen salvaging(UNS).This process is important for both maintaining ruminant nitrogen balance and supporting production of their major energy supply,bacterially-derived short chain fatty acids(SCFA).The key step in UNS is the trans-epithelial movement of urea across the ruminal wall and this is a highly regulated process.At the molecular level,the key transport route is via the facilitative urea transporter-B2,localized to ruminal papillae epithelial layers.Additional urea transport through aquaporins(AQP),such as AQP3,is now also viewed as important.Long-term regulation of these ruminal urea transport proteins appears to mainly involve dietary fermentable carbohydrates;whereas,transepithelial urea transport is finely regulated by local conditions,such as CO_(2) levels,pH and SCFA concentration.Although the key principles of ruminal urea transport physiology are now understood,there remains much that is unknown regarding the regulatory pathways.One reason for this is the limited number of techniques currently used in many studies in the field.Therefore,future research in this area that combines a greater range of techniques could facilitate improvements to livestock efficiency,and potentially,reductions in the levels of waste nitrogen entering the environment.

Effect of Incorporation of Wheat Straw and Urea into Soil on Biomass Nitrogen and Nitrogen-Supplying Characteristics of Paddy Soil

Pot experiments were carried out to study the effect of incorporation of wheat straw and/ or urea into soil on biomass nitrogen and mineral nitrogen and its relation to the growth and yield of rice.The combined appliation of wheat straw and urea increased much more biomass nitrogen in soil than the application of wheat straw or urea alone and consequently increased the immobilization of urea nitrogen added and reduced the loss of urea nitrogen.An adequate nitrogen-supplying process to rice plant could be obtained if C/ N ratio of the material added was about 20.The three yield components of rice were affected significantly by the status of nitrogen supplying.More than 30mg N/ kg soil of mineral nitrogen at effective tillering stage,panicle initiation stage and filling stage should be maintained in order to get high rice yield,though the criteria varied with the different experimental conditions.

Effects of controlled-release urea application on the growth, yield and nitrogen recovery efficiency of cotton

Field experiments were conducted to study the effects of the controlled release urea (CRU) application on growth yield and nitrogen recovery efficiency of cotton in the main cotton zone of the Yangtze River basin in 2010. Different nitrogen levels were set in order to determine the suitable dosage of CRU on cotton. The special purpose was to provide evidence for the CRU application in cotton fields. The results show that the application of CRU promotes the growth of cotton significantly and enhances the nitrogen supply in the whole period. Compared to the treatment with total N as base fertilizer (UB), the bod, flower, little bolls and total bolls are increased significantly. There are no significant differences in the yield between the CRU treatment and the treatment of controlled release urea and urea combined application (60%CRU + 40%U), but an increase by 12.38%-22.67% compared to the UB treatment, and an increase by 4.49%-7.23% compared to the treatments of total N split application (UD). The nitrogen uptake of CRU treatment was significantly increased by 13.01%-48.32% and 30.27%-13.01% than UB treatment and UD treatment, respectively. The nutrient recovery efficiency of CRU treatment is increased by 16.42-20.59, 5.92-11.29 and 4.22-12.59 percentage points compared to the UB treatment, UD treatment and 60%CRU + 40%U treatment, respectively. In this study, there was a good linearity relationship between the cotton yield and amount of CRU in Wuxue site. The yield of cotton response to amount of CRU could be described by the model of linear plus plateau in Jingzhou site.

Nitrogen deposition and release pattern of slow release fertiliser made from urea-impregnated oil palm frond and rubberwood chips

The fertiliser industry faces a continuing challenge to improve the efficiency of their products,particularly of nitrogenous fertilisers,and to minimise adverse impacts.Therefore,a new slow release fertilizer,ureaimpregnated woodchips from tropical plant biomass(oil palm frond and rubberwood),was developed.The morphology of the impregnated woodchips was investigated by scanning electron microscopy and the success of impregnation of urea and nitrogen deposition into the woodchips was confirmed by energy dispersive X-ray spectrometry.When nitrogen release patterns from impregnated woodchips fertiliser were simulated using a soil solution and distilled water as leaching solutions in a static condition for 768 h,release was slow and steady,although the release rate was lower in distilled water than in the soil solution.

Urea hydrolysis and recovery of nitrogen and phosphorous as MAP from stale human urine

Laboratory-scale tests for magnesium ammonium phosphate（MAP）precipitation following urea hydrolysis of human urine were conducted using orthogonal experiment design.The effects of initial pH,temperature and the volumetric ratios of stale urine to fresh urine,on urea hydrolysis in urine were studied to determine the final hydrolysis time to recover most nitrogen from separated human urine by MAP.With a volumetric ratio of stale to fresh urine>10% and at temperature≥20℃,urea hydrolysis could be completed in two days.Alkaline pH inhibited urea hydrolysis progress.The final pH values were all around 9.0 following urine hydrolysis,while the suspension pH might act as an indicator to detect the start and extent of urea hydrolysis.Over 95% of ammonium nitrogen and over 85% of phosphorus from hydrolyzed urine as MAP precipitate were obtained using MgCl;·6H;O and Na;HPO;·12H;O as precipitation agents at pH 8.5,molar ratio of Mg;:NH;-N:PO;-P at（1.2-1.3）:1:1,mixing speed of 120 r/min,and precipitation time and reaction time of 3 h and 15 min,respectively.The precipitate has a structure resembling pure MAP crystal.

Effects of supplementary urea-minerals lick block on the kinetics of fibre digestion, nutrient digestibility and nitrogen utilization of low quality roughages

Three yearling lambs with a rumen cannula were used to investigate the effects of supplementation with an urea-minerals lick block (ULB) on the kinetics of ruminal fibre digestion, nutrient digestibility and nitrogen (N) utilization of rice straw (RS), ammonia bicarbonate (AB)-treated RS (ABRS) and hay prepared from natural pasture. The digestibility of dry matter and organic matter of RS increased by 13.1% and 12.7% (P<0.05) when the diet was supplemented with ULB, and approached to that of ABRS, indicating that the effect of ULB on digestibility of RS is similar to that of AB treatment. The digestibility of ABRS was slightly improved by the ULB feeding. Nitrogen retention was highest in lambs fed on ABRS alone, followed by hay with ULB, and was lowest in animals fed on RS with ULB. However, both the amount and proportion of N retention to N intake were enhanced by ULB supplementation to lambs fed on hay. The proportion of N retained to N digested decreased due to ULB sup-plementation to lambs fed on RS or ABRS. Supplementing ULB did not greatly influence the rumen degradation of either dry matter or crude protein in each of the three diets. RS and hay had similar values in the potential extent of digestion (PED) and digestion rate of PED (kd) of fibrous materials, but the discrete lag time for RS was lower than that for hay. The AB treatment significantly increased the PED (P<0.05) and kd (P<0.05) of RS. Neither the PED nor kd for RS and ABRS was influenced by ULB supplementation, but the kd for hay significantly increased due to ULB. The lag time for hay was also shortened by the ULB feeding. The ULB improved the digestion of fibre in the rumen of lambs fed on low quality roughage. It is inferred that while ULB is effective in increasing nutrient digestibility of low quality roughages by improving ruminal fibre digestion. A synchronized supply of N and energy to rumen microbes should be considered to improve the efficiency of N utilization when the basal diet is ammoniated straw.

Reducing Nitrogen Loss in Subsurface Tile Drainage Water with Managed Drainage and Polymer-Coated Urea in a River Bottom Soil

Poorly-drained, river bottom soils can be high corn (Zea mays L.) yielding environments, but saturated soil conditions often reduce corn yields. Wabash soils located in river bottoms in Northeast Missouri have not been traditionally tile drained due to high clay content which requires narrow tile drain spacings. Increased land prices in the region have increased interest in tile draining poorly-drained bottom land soils to increase corn yields which could have a deleterious effect on water quality. The objectives of the three-year study were to determine whether use of managed subsurface drainage (MD) in combination with a controlled release N fertilizer could reduce the annual amount of NO3--N loss through tile drainage water compared to free subsurface drainage (FD) with a non-coated urea application. Annual NO3--N loss through tile drainage water with FD ranged from 28.3 to 90.1 kg·N·ha-1. Nitrogen fertilizer source did not affect NO3--N loss through tile drainage water, which was likely due to limited corn uptake over the three-year study due to adverse weather conditions. Averaged over three years, MD reduced tile water drained 52% and NO3--N loss 29% compared to FD. Reduction in NO3--N loss through tile drainage water with MD compared to FD was due to reduced tile flow during the non-cropping period. Annual flow-weighted mean concentration of NO3--N in the tile water was 5.8 mg·N·L-1 with FD and 8.1 mg·N·L-1 with MD. Tile draining river bottom soils at this location for continuous corn production may not pose a health risk over the evaluated duration.

血尿素氮与白蛋白比值对急诊脓毒症患者预后的评估价值

目的探讨血尿素氮与白蛋白比值(BAR)对急诊脓毒症患者预后的评估价值。方法本研究采用回顾性观察的研究方法,收集了2021年3月至2022年3月在首都医科大学附属北京朝阳医院急诊抢救室治疗的313例脓毒症患者的基本信息和实验室检查数据。根据在院治疗期间是否死亡将患者分为存活组(229例)和死亡组(84例)。比较2组患者临床和实验室检查资料,分析患者住院期间死亡的危险因素。采用受试者工作特征(ROC)曲线评价BAR对脓毒症患者预后的评估价值。结果死亡组年龄、急性生理学与慢性健康状况评分系统Ⅱ(APACHEⅡ)评分、心率、脑梗死比例明显高于存活组,收缩压、舒张压、慢性阻塞性肺疾病比例低于存活组,差异均有统计学意义(均P<0.05)。死亡组白细胞计数、中性粒细胞绝对值、C反应蛋白、降钙素原、血尿素氮、天冬氨酸转氨酶、BAR高于存活组,淋巴细胞绝对值、白蛋白水平低于存活组(均P<0.05)。多因素Logistic回归分析结果显示,BAR(P=0.025)、APACHEⅡ评分(P<0.001)是脓毒症患者住院期间死亡的独立危险因素。ROC曲线分析结果显示,BAR预测脓毒症患者住院期间死亡的曲线下面积(AUC)为0.728,APACHEⅡ评分的AUC为0.814,BAR+APACHEⅡ评分的AUC为0.824,联合预测效果优于单独应用BAR。BAR与APACHEⅡ评分联合预测时可以获得较好的敏感度和特异度(敏感度为77.4%,特异度为75.5%)。结论BAR、APACHEⅡ评分是脓毒症患者预后的独立危险因素。BAR对急诊脓毒症患者预后具有中等的预测能力,特异度较高。与单独应用BAR相比,BAR联合APACHEⅡ评分具有更好的预测能力,其敏感度更好,同时具有较高的特异度。

血清肾胺酶、尿调节素、可溶性尿激酶受体联合检测对糖尿病肾损伤早期诊断的价值分析

目的探究血清肾胺酶(RNLS)、尿调节素(UMOD)、可溶性尿激酶型纤溶酶原激活物受体(suPAR)联合检测对糖尿病肾损伤早期诊断的价值。方法选取2020年3月至2021年3月成都市第七人民医院收治的61例糖尿病肾损伤病人为糖尿病肾损伤组,按24 h尿白蛋白排泄率(UAER)分为早期糖尿病肾病组(29例)和临床期糖尿病肾病组(32例),选取66例糖尿病病人为单纯糖尿病组,另选取同期健康体检者60例为对照组。收集病人的一般临床资料并比较,采用尿素酶法检测血清尿素(UREA),氧化酶法检测肌酐(Cr)和尿酸(UA)水平,采用酶联免疫吸附法(ELISA)检测血清RNLS、UMOD、suPAR的水平。Pearson相关性分析RNLS、UMOD、suPAR与UREA、Cr、UA以及临床资料的关系。采用受试者操作特征(ROC)曲线分析血清RNLS、UMOD、suPAR联合检测对糖尿病病人发生肾损伤的诊断价值。结果糖尿病肾损伤组、单纯糖尿病组三酰甘油、总胆固醇、空腹血糖、糖化血红蛋白及血清UREA、Cr、UA、suPAR水平[(133.56±42.68)ng/L,(66.48±17.13)ng/L比(34.15±8.26)ng/L]均显著高于对照组(P<0.05),估算肾小球滤过率(eGFR)及血清RNLS[(28.62±7.61)mg/L,(35.47±9.29)mg/L比(42.81±13.24)mg/L]、UMOD水平[(64.28±16.82)g/L,(119.45±28.65)g/L比(139.82±32.84)g/L]均显著低于对照组(P<0.05);且糖尿病肾损伤组较单纯糖尿病组升高或下降幅度大(P<0.05)。糖尿病肾损伤组糖尿病病程显著高于单纯糖尿病组(P<0.05),24 h尿蛋白显著高于单纯糖尿病组和对照组(P<0.05)。临床期糖尿病肾病组病人血清RNLS[(26.28±6.69)mg/L比(31.18±8.34)mg/L]、UMOD水平[(51.26±14.41)g/L比(78.65±19.49)g/L]较早期糖尿病肾病组均显著降低(P<0.05),suPAR水平[(151.96±48.03)ng/L比(113.27±36.81)ng/L]显著升高(P<0.05)。RNLS、UMOD与UREA、Cr、UA、三酰甘油、总胆固醇、空腹血糖、糖化血红蛋白、糖尿病病程及24 h尿蛋白均呈负相关(P<0.05),与eGFR呈正相关(P<0.05);suPAR与UREA、Cr、UA、三酰甘油、总胆固醇、空腹血糖、糖化血红蛋白、糖尿病病程及24 h尿蛋白均呈正相关(P<0.05),与eGFR呈负相关(P<0.05)。ROC曲线分析结果显示,血清RNLS、UMOD、suPAR三项联合的曲线下面积(AUC)0.88显著高于RNLS、UMOD单项检测的AUC(0.81、0.83)(P<0.05),而与suPAR AUC比较差异无统计学意义(P>0.05)。结论糖尿病肾损伤病人血清RNLS、UMOD、suPAR水平呈异常表达,且三项联合检测对糖尿病病人发生肾损伤的诊断价值较高,值得临床推广应用。

糖尿病患者房水细胞因子与肌酐、尿素氮、糖化血红蛋白的相关性分析

目的观察糖尿病患者房水中各种细胞因子的含量及其与肌酐、尿素氮、糖化血红蛋白、糖尿病视网膜病变眼底分级之间的相关性。方法横断面临床研究。将2021年3月—2022年3月在金华市中心医院行白内障手术的2型糖尿病患者53例(53眼)纳入研究,同时选取同期行单纯白内障手术的非糖尿病患者27例(27眼)作为对照。手术前收取术眼房水标本,采用细胞微球芯片技术检测2组患者房水中的IL-6、IL-8、IL-10、血管内皮生长因子(VEGF)、单核细胞趋化蛋白-1(MCP-1)、细胞间黏附分子(ICAM)、干扰素-γ(IFN-γ)和血清肿瘤坏死因子-α(TNF-α)等细胞因子的含量,比较2组患者房水细胞因子含量,并分析糖尿病组房水细胞因子与肌酐、尿素氮、糖化血红蛋白、糖尿病眼底病变分级之间是否有相关性。结果除IL-10外,糖尿病组房水中的IL-6、IL-8、VEGF、MCP-1、ICAM、TNF-α、IFN-γ均明显高于对照组,差异具有统计学意义(P<0.05)。在糖尿病患者中,肌酐与房水中的IL-8、VEGF、ICAM、TNF-α呈正相关;尿素氮与房水中的IL-6、IL-8、VEGF、MCP-1、ICAM呈正相关;糖尿病眼底分级与房水中的IL-8、VEGF、MCP-1呈正相关;糖化血红蛋白与房水中的各种细胞因子均无明显相关性。结论在糖尿病患者中,肌酐和尿素氮的水平可以预测其房水中的部分细胞因子水平的高低;故而在临床工作中,需重点关注肌酐和尿素氮,可为预测该类患者术后的炎症反应程度及眼底病变程度提供依据。

Study on Membrane Microstructures and Characteristics of Infrared Spectra and Nitrogen Release of Solid-Liquid Reaction Coated Urea

The membrane microstructures and the mechanism of two coated ureas formed through solid- liquid reaction were observed by scanning electron microscope and infrared spectra, the relation of the structural characteristics with the nitrogen release feature was also discussed by combining with nitrogen dissolution in water. The results showed that the membranes were made of solid particles tightly connected to each other and were piled up layer by layer through liquid glue. Porosity and aperture of membrane were determined by compactness of piled layers and the particles in a single layer and also related to the characteristics of coating materials. Research of the infrared spectra of membrane, made of a solid powder and a liquid glue, proved that O-H on the solid surface was bonded with the double bond of the liquid glue, thus forming membrane and keeping it stable. It was found that the two coated ureas showed obvious differences in nitrogen releasing due to their membrane structures, the porosity and aperture of membrane were the critical factors for nitrogen releasing.

控失尿素对氮素利用率、土壤硝态氮含量及冬小麦增产效果的影响

为探索控失尿素的施用方法,发现控失尿素在施用中存在的问题,以冬小麦为试验对象,开展了田间小区试验,考察了不同施肥处理和施肥方式对冬小麦产量、氮素利用率和土壤硝态氮含量的影响。结果表明:施氮处理的冬小麦产量高于不施氮处理的,处理间差异极显著;氮素施用量和施肥方式相同时,控失尿素处理的冬小麦产量高于普通尿素处理的,处理间差异极显著;氮素施用量和肥料品种相同而施肥方式不同时,底施+追施的增产效果优于全底施的,处理间差异显著;控失尿素氮素施用量比普通尿素减少20%的条件下,冬小麦产量无显著性差异;与施用普通尿素的处理相比,施用控失尿素的处理不仅氮素利用率高,且均不同程度地降低了土壤中硝态氮的含量。施用控失尿素可以提高冬小麦的产量和氮素利用率,降低土壤中硝态氮的含量。

缓控释肥配施脲铵运筹对水稻产量、氮素利用效率和土壤养分的影响

通过田间试验,以传统配方肥+尿素一基两追施肥模式(CG)为对照,研究了以脲甲醛类缓控释肥(NC)和木质素类缓控释肥(MC)为基肥、脲铵为分蘖或穗分化追肥的缓控释肥+脲铵一基一追施肥模式对水稻产量、氮吸收累积、氮素利用效率以及土壤养分的影响。结果表明:缓控释肥+脲铵一基一蘖施肥模式水稻产量与CG处理相比无明显差异,但脲甲醛类缓控释肥+脲铵(NC-S)和木质素类缓控释肥+脲铵一基一穗(MC-S)处理分别比CG处理明显增产3.96%和6.01%,主要原因为NC-S和MC-S处理每穗粒数分别比CG处理明显增加16.7%和17.6%;与CG处理相比,脲甲醛类缓控释肥+脲铵(NC-F)和木质素类缓控释肥+脲铵一基一蘖(MC-F)处理成熟期地上部氮累积分别比CG处理增加2.50%和5.89%,NC-S和MC-S处理分别比CG处理明显增加10.0%和11.6%;NC-S和MC-S处理氮素利用效率(NUE)分别比CG处理高3.96%和6.01%。缓控释肥+脲铵一基一追施肥模式增加了水稻氮吸收效率(NupE)和表观氮肥回收效率(ANR),其中MC-S处理的NupE明显比CG处理高11.6%,NC-S和MC-S处理的ANR分别比CG处理明显高25.4%和29.3%。缓控释肥+脲铵一基一追施肥模式土壤碱解氮含量明显比CG处理增加6.58%~10.7%,其中,一基一穗施肥模式增加比例更大;另外,土壤有机质含量比CG处理增加1.11%~7.56%。由此可见,缓控释肥+脲铵一基一穗施肥模式更有利于提高水稻产量和氮素利用效率,增加土壤肥力。