土壤中的硝态氮检测试纸的制备及应用

根据NO-2氧化碘离子为单质碘,而碘遇淀粉显色这一反应特性,通过改变模拟土壤浸提液的pH值、催化剂用量、反应时间等还原浸提液中的硝态氮,探索出制备淀粉碘化钾试纸的最佳条件,并制作出标准色阶谱图。实验以分光光度法为验证手段,试纸法测量的土壤硝态氮含量与仪器检测结果基本吻合,且其它共存离子对显色几乎没有影响。     

拉曼光谱法快速测定肥料中硝态氮含量

研究用便携式激光拉曼光谱仪测定肥料中硝态氮含量,建立了激光拉曼光谱法测定硝酸铵含量的模型。结果表明,该方法用于实际样品检测的结果准确度和精密度良好,与国标法的测定结果基本吻合。     

硝态氮与铵态氮

硝态氮和铵态氮是作物能直接吸收的两种有效态氮源。20世纪30年代的经典实验已证明:这两种氮源对作物氮营养的效用等价,但在不同的具体条件下存在差异。据此简要讨论了作物对两种氮源的吸收、储存和代谢特点,及其在不同营养环境下的差异。借以全面理解两种氮源的作用,并有助于评价和解释我国近年来对不同作物在不同营养环境下完成的大量对比试验结果。     

不同浓度亚硝态氮在弱碱性土壤中的转化规律研究

选取陕西省华县耕作土壤,在实验室条件下研究该弱碱性土壤在不同初始浓度的亚硝态氮(11.2,56,112,280,560 mg/kg土)存在下的氮的转化规律,并进一步阐明亚硝态氮在该土壤中的累积效应。结果表明,土壤中的亚硝态氮的累积效应随着浓度的增大不断增强,即土壤中亚硝态氮转化为硝态氮的转化时间随着亚硝态氮的初始浓度的增加而增加。但是,高浓度的亚硝态氮(560 mg/kg)向硝态氮转化过程中,从第10 d开始,亚硝态氮的转化速率明显下降,低于初始浓度为280 mg/kg时的状态,反应受到强烈的抑制作用;当调整土壤的初始pH值时,该浓度下的抑制作用也几乎不被影响。因此,对出现高浓度亚硝态氮的地区环境需要引起重视,并及时采取一定的措施,以防止其对人类健康产生进一步的影响。     

不同浓度亚硝态氮在弱碱性土壤中的转化规律研究

选取陕西省华县耕作土壤,在实验室条件下研究该弱碱性土壤在不同初始浓度的亚硝态氮(11.2,56,112,280,560 mg/kg土)存在下的氮的转化规律,并进一步阐明亚硝态氮在该土壤中的累积效应。结果表明,土壤中的亚硝态氮的累积效应随着浓度的增大不断增强,即土壤中亚硝态氮转化为硝态氮的转化时间随着亚硝态氮的初始浓度的增加而增加。但是,高浓度的亚硝态氮(560 mg/kg)向硝态氮转化过程中,从第10 d开始,亚硝态氮的转化速率明显下降,低于初始浓度为280 mg/kg时的状态,反应受到强烈的抑制作用;当调整土壤的初始pH值时,该浓度下的抑制作用也几乎不被影响。因此,对出现高浓度亚硝态氮的地区环境需要引起重视,并及时采取一定的措施,以防止其对人类健康产生进一步的影响。     

肥料中氨态氮、硝态氮、尿素态氮含量的测定与比较

本文主要介绍了肥料中的氨态氮、硝态氮、尿素态氮含量测定的反应原理以及测定方法的比较。     

硝态氮在经济作物专用肥的应用

烟草、棉花、辣椒等经济作物的专用肥中配入一定比例的硝态氮 ,可提高其产量、质量 ,介绍几种经济作物专用肥的原料配比及产品质量     

粤东茶园土壤硝态氮含量的状况研究

采用紫外分光光度法测定粤东潮安县凤凰镇11个茶园土壤的硝态氮含量,结果表明．大多数茶园土壤硝态氮含量没有超过标准,污染较轻。用紫外分光光度法测定土壤硝态氮含量稳定性高,精密度好,适合一般的科研分析要求。     

土壤中硝态氮及镍含量的检测研究

土壤是植物生长的基本源地,土壤的健康状况在整个农业构建元素体系构建中占有重要的地位。为改善与提高土壤的健康,需要加强对土壤中营养成分及重金属的监督与检测。基于此,基于紫外分光光度法化学模型在土壤中的应用进行分析,以检测土壤中硝态氨及镍为切入点,阐述硝态氨与镍的概念及性质,运用实验法分析硝态氨及镍成分含量,最后针对测试结果,对土壤性质分析进行定量与可视化分析。     

含硝态氮的国产化肥少了

我国生产的氮肥数量巨大,但含硝态氮的化肥所占比例很小,这不利于化肥的合理施用.铵态氮和硝态氮作为植物的氮源,两者基本上是等效的,要根据作物和土壤条件合理施用.我国应当适当增加含硝态氮化肥的生产.第一,要对硝酸铵进行改性,使之不能再制造炸药;第二,要消除认为用了硝态氮肥就不能生产绿色食品的错误认识.     

中国硝酸钾发展概况与市场前景

硝酸钾既是重要的工业原料,又是优质无氯钾、氮复合肥料,植物营养素钾、氮的总质量分数可达60%左右,是发展现代高效农业不可缺少的化肥品种。由于生产、市场、价格等方面的原因,目前硝酸钾在中国施用较少,而这种称为世界紧缺的"绿色钾肥"在欧洲国家较为盛行。伴随着高科技农业的不断发展,以及人们对食品安全要求的不断提高,中国市场对硝酸钾的需求将不断增加,不过目前这一市场仍表现出过于狭窄。简要介绍了硝酸钾的生产技术、中国硝酸钾生产发展现状、硝酸钾应用领域及市场前景,并对硝酸钾的发展提出了一些建议。     

Rapid Detection of Available Nitrogen in Soil by Surface-Enhanced Raman Spectroscopy

Soil-available nitrogen is the main nitrogen source that plants can directly absorb for assimilation. It is of great significance to detect the concentration of soil-available nitrogen in a simple, rapid and reliable method, which is beneficial to guiding agricultural production activities. This study confirmed that Raman spectroscopy is one such approach, especially after surface enhancement; its spectral response is more sensitive. Here, we collected three types of soils (chernozem, loess and laterite) and purchased two kinds of nitrogen fertilizers (ammonium sulfate and sodium nitrate) to determine ammonium nitrogen (NH₄-N) and nitrate nitrogen (NO₃-N) in the soil. The spectral data were acquired using a portable Raman spectrometer. Unique Raman characteristic peaks of NH₄-N and NO₃-N in different soils were found at 978 cm⁻¹ and 1044 cm^−1, respectively. Meanwhile, it was found that the enhancement of the Raman spectra by silver nanoparticles (AgNPs) was greater than that of gold nanoparticles (AuNPs). Combined with soil characteristics and nitrogen concentrations, Raman peak data were analyzed by multiple linear regression. The coefficient of determination for the validation (Rp2) of multiple linear regression prediction models for NH₄-N and NO₃-N were 0.976 and 0.937, respectively, which deeply interpreted the quantitative relationship among related physical quantities. Furthermore, all spectral data in the range of 400–2000 cm⁻¹ were used to establish the partial least squares (PLS), back-propagation neural network (BPNN) and least squares support vector machine (LSSVM) models for quantification. After cross-validation and comparative analysis, the results showed that LSSVM optimized by particle swarm methodology had the highest accuracy and stability from an overall perspective. For all datasets of particle swarm optimization LSSVM (PSO-LSSVM), the Rp2 was above 0.99, the root mean square errors of prediction (RMSE_P) were below 0.15, and the relative prediction deviation (RPD) was above 10. The ultra-portable Raman spectrometer, in combination with scatter-enhanced materials and machine learning algorithms, could be a promising solution for high-efficiency and real-time field detection of soil-available nitrogen.     

Field study of the fate of labelled fertilizer nitrate applied to barley and maize in sandy soils

The recovery in crop and soil of labelled fertilizer nitrate applied to barley and maize growing on a sandy soil was measured. The experimental plots, each measuring 4m × 4m, were situated on fields growing with barley and with maize. The barley received 50 kg N/ha as KNO₃ enriched with 5.99 At.%¹⁵N excess while the maize received 113 kg N/ha as KNO₃ labelled with 5.014 At.%¹⁵N excess. Otherwise, the plots were treated the same as the rest of the field. At harvesting, the barley and the maize plots were subdivided into nine and six sub-plots respectively. Plant samples, including the roots and soil samples up to 1 m depth were collected in each sub-plot. Fertilizer N recovery in the samples was measured. In the plants, the N derived from the fertilizer (Ndff) was 24.0% and 16.7% in barley and maize, respectively. The percentage of the applied fertilizer recovered by barley was 57%; for maize, only 18%. The movement of fertilizer N was restricted to the top 50 cm in the barley plot, whereas in the maize plot, the fertilizer N could be detected down to 90 cm. The amount of fertilizer N remaining in the soil at harvest was 32% for the barley and 68% for the maize plot. The loss of fertilizer N under barley was 10% and 14% under maize. The loss was attributed mainly to denitrification. The means and the variances of total N uptake by plants inside the¹⁵N plot and outside the¹⁵N plot were compared. They did not differ significantly, indicating that the results obtained from the¹⁵N plot can be extrapolated to the rest of the field.     

肥料中硝态氮、铵态氮、总氮的研究

研究仅含硝态氮、铵态氮的肥料,结果表明,用GB/T8572-2010《复混肥料中总氮含量的测定蒸馏后滴定法》检测含有硝态氮、铵态氮的肥料中铵态氮含量、硝态氮含量(差减法总氮含量-铵态氮含量=硝态氮含量)(标准GB/T8572-2010《复混肥料中总氮含量的测定蒸馏后滴定法》中没有体现总氮含量-铵态氮含量=硝态氮含量,这是根据铵态氮与硝态氮性质总结研究出来的)与标准NY/T1116-2014《肥料硝态氮、铵态氮、酰胺态氮含量的测定》单独检测铵态氮含量、硝态氮含量结果无显著性差异。GB/T8572-2010检测总氮含量与SN/T0736.5-2010《进出口化肥检验方法第5部分:氮含量的测定》检测总氮含量无显著性差异。     

中国硝酸盐资源开发利用现状及其前景展望

详细论述了我国硝酸盐资源概况以及资源开发与研究现状,同时对世界硝酸盐资源开发情况进行了综述.结合目前我国硝酸盐资源勘察程度、技术现有水平及市场需求,客观地分析了我国硝酸盐资源开发前景.     

酚醛树脂检测方法与国际标准的对照研究

国内酚醛行业尚未建立国家标准。根据酚醛树脂工业快速发展的特点,酚醛树脂行业应尽快采用统一的相关检验标准。为了同国际标准接轨和提升中国酚醛树脂工业水平,用国内通用的检验方法、仪器设备和ISO标准方法及仪器,检测了树脂中游离酚、水分,粘度和细度等重要项目指标,并进行研究对照。其差距说明必须尽快采用ISO标准的实用价值和意义,为酚醛树脂建标做好前期准备。     

The potassium status of soils: Significance of the “Italian ryegrass test”

There is a simple relationship between the amounts of K extracted from soil by ammonium acetate or sulphuric acid and by Italian ryegrass provided that the grass is grown on a small amount of soil and that the time required for K exhaustion by the grass is short and that exhaustion is achieved as indicated, for example, by the absence of regrowth. In general, ryegrass can extract more K from grassland soils than can chemical reagents, even sodium tetraphenylborate. The pool of soil K exploited by ryegrass although larger than that obtained by acetate or sulphuric acid, does not include it completely. The reagents remove from the soil a little K which the roots cannot reach but do not extract the whole pool actually available to the roots. The maximum quantity of K extractable by ryegrass can be deduced from the K content of the herbage after three weeks test cropping even when conditions are not strictly controlled. This applies only if the ryegrass roots colonise the soil quickly and completely as when the volume of soil is limited so that growth is entirely dependent on the amount of available K.(with the technical cooperation of M. Duyme)     

Development of an accelerated test on concrete prisms to determine their potential for Alkali-Silica reaction

An accelerated laboratory test on concrete prisms is being developed which shows good correlation with the observed field performance of concrete structures damaged due to Alkali-Silica Reaction (ASR). The procedure for the test was determined by collecting a substantial database on actual structures affected by ASR. The main factors common to the affected structures were the use of high cement contents in the range 450 to 500 kg/m³ in association with the use of initial steam curing.     

Development of nitrogen fertilizer recommendations for arable crops in the Netherlands in relation to nitrate leaching

In the Netherlands, current nitrogen fertilizer recommendations for arable crops are based on the amount of soil mineral nitrogen in early spring. The larger the amount of soil mineral nitrogen, the lower the recommended application rate of fertilizer nitrogen. A more refined method is to draw up a balance sheet in which the nitrogen requirement of the crop is given on the one side and the contributions of fertilizer nitrogen, soil mineral nitrogen, and the amount of nitrogen mineralized during the growing period on the other. The most refined method of nitrogen fertilizer recommendation is the use of a simulation model that predicts the daily crop nitrogen requirement and nitrogen supply to the crop from various pools during the growing period. A simulation model thus adds the time element to nitrogen fertilizer recommendations. Moreover, in contrast with the other two methods, a simulation model allows identification of environmental side-effects of nitrogen fertilizer application.The current Dutch nitrogen fertilizer recommendations aim at predicting the economically optimum application rate of fertilizer nitrogen. From the environmental point of view it is interesting to know how much soil mineral nitrogen has accumulated in the soil at harvest, because this nitrogen is a potential loss to the environment through nitrate leaching during the subsequent winter period. If the economically optimum application rate of fertilizer nitrogen is applied to arable crops, it is unlikely that soil mineral nitrogen accumulates, except in the case of potatoes. Model calculations have shown that accumulation of soil mineral nitrogen after potatoes can be prevented when the recommended nitrogen application rate is reduced by 25%. In that case tuber yield is reduced by only 2%.