Long-term effect of N and P fertilization on a pearlmillet—wheat cropping system

Results of an eight-year study on long-term effect of N and P application in a pearlmillet—wheat sequence is reported. There was little or no residual effect of N on any of the crops. Pearlmillet needed 70 to 80 kg N and wheat required more than 120 kg N ha^–1 every year for optimum grain yield. There was no soluble P build up in soil by continuous P application. Fertilizing wheat every year with 19 kg P and pearlmillet with 13 kg P ha^–1 is considered optimum.Continuous cropping leading to a production of 216 tonnes of biomass ha^–1 in 17 crops and use of high analysis N (urea) and P (triple superphosphate) fertilizers had not impaired the K and Zn supplying capacity of these alluvial soils containing illite clay minerals. The experiment is being continued to monitor the productivity of the soil as affected by continuous cropping.     

Phosphorus management of a rice-wheat cropping system

A long term field experiment was conducted on a sandy loam soil from 1983 to 1987 to determine how to best apply phosphorus fertilizer in a rice-wheat cropping system. The treatments included 9 combinations of phosphorus application either to both rice and wheat or to rice or wheat alone. Direct application of phosphorus at 13 kg/ha to both the crops resulted in significantly higher total productivity of the rice-wheat cropping system as compared with 26 kg P/ha applied either to rice or wheat alone. Phosphorus at 13 kg/ha for rice and 26 kg/ha for wheat was as efficient as 13 kg P/ha for rice and 13 kg P/ha for wheat. The higher rate of P (26 kg/ha) applied to both rice and wheat resulted a decline in the total productivity. The residual effects of phosphorus applied to either rice or wheat were significant to the succeeding crop but was inferior to its direct application. Phosphorus increased the leaf area index, chlorophyll content of leaves, and interception of more photosynthetically active radiation (PAR) which resulted in increased grain yield of rice and wheat. Phosphorus status of the surface soil declined markedly, in the absence of P application from 15.4 to 6.4 kg P/ha. Phosphorus applied at 26 kg P/ha to both the crops resulted a build up of the available P status of soil. Phosphorus application at 13 kg/ha to both rice and wheat maintained the phosphorus status of the soil at original level.     

Long term effects of inorganic fertilizer inputs on crop productivity in a rice-wheat cropping system

Three levels of N (40,80,120 kg N ha^-1) and P (0,17.5,35 kg P ha^-1), and 2 levels of K (0,33 kg K ha^-1) were tested for 19 years in rice and wheat crops of a rice-wheat cropping system in a fixed layout of 3×2×2 factorial partially confounded design along with one control and 3 replications. From this trial, data of 7 treatments, i.e. 0-0-0, 40-35-33, 80-35-33, 120-35-33, 120-0-0, 120-35-0 and 120-0-33 kg ha^-1 N-P-K respectively were compared for yield trends, changes in response functions, soil organic -C and available N,P,K status. Soil organic - C decreased in unfertilized plots by 62% (over initial value of 0.45%) but increased by 44, 40 and 36% in plots receiving 120-35-33, 120-35-0 and 80-35-33 kg ha^-1 N-P-K respectively. Available N was also greatest in these same three treatments. Available soil P increased by about 5 fold in 15 years in treatments supplied with fertilizer P, but no significant change was detected in treatments without P addition. Yields of rice and wheat exhibited linear declining trend in all treatments. The highest rate of decline (89 kg ha^-1 year^-1 in rice and 175 kg ha^-1 year^-1 in wheat), however, was found when 120 kg ha^-1 N was applied alone. The least rate of decline of 20 kg ha^-1 year^-1 in rice and 58 kg ha^-1 year^-1 in wheat was observed when 40-35-33 kg ha^-1 N-P-K respectively was applied to both the crops. At currently recommended levels of NPK (120-35-33 kg ha^-1), the rate of decline in yields was 25 kg ha^-1 year^-1 for rice and 62 kg ha^-1 year^-1 for wheat. Possible causes of these yield declines are discussed.     

磷泥中黄磷的提取方法研究

磷泥是电炉法生产黄磷过程中产生的主要副产物之一,针对磷泥中黄磷回收的方法和研究现状,介绍了水煮法、蒸馏法、电场法、溶剂萃取法、盐酸-硝酸法、纯碱法、氨解法、碳铵-烧碱-双氧水法等,讨论了各种方法的特点,指出存在的问题和今后的研究重点。     

磷矿中磷的测定方法初探

采用“以二甲酚橙为指示剂 ,用硝酸铋标准溶液直接滴定试液中的 PO43 -”的方法来测定磷矿中的磷     

与黄磷生产装置有关的制磷电炉规模问题探析

针对我国的磷矿资源分布、经济发展、交通与能源结构等实际情况,探讨了黄磷生产的电炉电耗、原材料消耗和产品质量及水电资源的合理利用,认为制磷企业根据当地资源情况配置多台制磷电炉是适宜的。     

黄磷脱硫研究

用吸附力法对工业黄磷中的硫进行脱除净化，可使硫含量降至２５μｇ／ｇ以下，提高了黄磷的品质．拓展了黄磷的加工应用领域。并无其它有害杂质及金属元素重新引人，不产生环境污染。     

磷石膏中有效磷的测定方法比较

分别用EDTA、中性柠檬酸铵两种萃取剂萃取并测定磷石膏中有效磷含量,通过比较,选择能够完全萃取磷石膏中有效磷的萃取剂——中性柠檬酸铵,用于磷石膏中有效磷的分析测定。     

Phosphorus sorption capacity of low activity clay soils of South Western Nigeria and its usefulness in evaluating P requirement of rice

Field and laboratory experiments were conducted on 15 low activity clay soils in Ogun State of Nigeria to evaluate the relationships between P sorption capacity and some soil properties and the use of sorption indices in evaluating the P requirement of rice. Langmuir adsorption capacity (b) varied from 30.9 to 414.3 µg g^–1. Although adsorption capacity was related significantly to a number of soil properties, citrate dithinonite bicarbonate (CDB) extractable Fe was the most important variable accounting for 99% of the variation in adsorption capacity. The solution P concentration (SPC) required to achieve 95% maximum grain yield of rice varied from 0.03 in a sandy clay soil to 0.19 µg ml^–1 in a sandy soil, while the quantity of fertilizer P required to attain the solution P concentration (Standard Phosphate requirement, SPR) varied from 14.1 to 88.7 kg ha^–1. Highly significant power function relationships were obtained between SPC and b (r=0.93) and between SPR and b (r=0.93). The P buffering capacity (PBC) of the soils indicated that the soils are moderately buffered. However, SPR accounted best for the variation in grain yield of rice on the field (R²=0.90). The use of P sorption indices in estimating P needs of rice appears superior to the use of chemical extractants.     

泥磷中温真空提取黄磷的技术研究

该法可提取泥磷中96. 9%以上的黄磷,提取黄磷的含量可达99. 94%,杂质砷含量仅为0. 00958%,达到国家标准工业黄磷中优等品要求。     

不同絮凝剂的除磷效果研究

在室温条件下,利用常见的三种絮凝剂(PAC、FeCl3、Al2(SO4)3)对人工配置的含磷废水进行混凝处理,寻找对应最佳处理效果的投药量和pH。结果表明,Al2(SO4)3的最佳投药量为60 mg/L,最佳pH为7.0;FeCl3的最佳投药量为40 mg/L,最佳pH为10.05;PAC投药量为120 mg/L,最佳pH为8.0。     

回流污泥预浓缩强化新型氧化沟系统生物除磷的研究(英文)

A pilot-scale,pre-anoxic-anaerobic oxidation ditch was used in this study to treat municipal wastewater with limited carbon source.A novel return activated sludge(RAS) pre-concentration tank was adopted for improv-ing the phosphorus removal efficiency and the effects of RAS pre-concentration ratio were studied.Under the opti-mal operational condition,the suspended total phosphorus(STP) and the total phosphorus(TP) removal efficiencies were around 58.9% and 63.9% respectively and the effluent-P was lower than 0.8 mg·L-1.The reason is that with the optimal RAS pre-concentration ratio,nitrate is completely removed with endogenous carbon source and the secondary phosphorus release is strictly restrained in the pre-anoxic tank.Therefore,the anaerobic phosphorus release and the carbon source uptake by phosphorus accumulation organisms(PAOs) in the sludge,which are ex-tremely important to the phosphorus removal process,can be fully satisfied.Furthermore,the oxidation-reduction potential is proved to be suitable for controlling the RAS pre-concentration ratio due to influent fluctuation and varied conditions.The novel modified system is also beneficial for PAO accumulation.     

Zinc and phosphorus interaction in a wheat-maize cropping system

To study the interaction effect of Zn and P in a wheat-maize cropping system, a field experiment was conducted at the H.P. Agricultural University Research Station, Palampur (India). Zinc was applied as ZnSO₄·7H₂O at the rate of 0, 20 and 40 kg per ha and P as superphosphate at the rate of 0, 60 and 120 kg per ha. The direct Zn-P interaction effect was investigated on wheat (S—308) and its residual effect on maize (early composite). Added Zn did not increase the grain and straw yield of wheat when P was not applied, but when P was applied, 20 kg per ha added Zn responded significantly. Contrary to this, in maize, only 20 kg per ha added Zn responded significantly when P was not applied, but when P was applied, even 40 kg per ha Zn increased the grain and straw yield of maize. The grain and straw yield of wheat and maize were higher under limed than under unlimed conditions.The concentration of Zn increased with the application of Zn and decreased with the application of P. The concentration of Zn was comparatively higher in grain than in straw of wheat and maize. The P concentration in wheat and maize plants decreased with the increasing levels of applied Zn. The concentrations of Zn were lower under limed than under unlimed condition, whereas the reverse was true for P concentrations.The respective absorption of Zn and P in wheat was 9.7 and 7.3 per cent upto tillering, 47.9 and 49.4 per cent between tillering and flowering, and 42.3 and 43.3 per cent between flowering and maturity. The corresponding absorption of Zn and P in maize was 11.7 and 9.4, 59.9 and 52.1, and 29.3 and 38.5 per cent before booting stage, between booting and tasseling stage and between tasseling and maturity stage, respectively. At maturity, about 53.1 and 13.0 per cent of the Zn and P taken up were retained by wheat straw and 46.9 and 87.0 per cent by wheat grain. The respective values for Zn and P in maize straw and grain were 66.8 and 30.3 and 33.2 and 69.7 per cent. When more Zn was applied, less Zn was translocated to grains; when more P was added, more Zn was translocated to grains. The effects of P and Zn on P distribution at maturity were opposite to that of Zn distribution.     

Changes in soil available NPK in multiple cropping systems based on short duration sugarcane crops relative to a conventional sugarcane cropping system

Changes in soil available NPK were studied in four intensive crop rotations based on short duration (8 months) sugarcane crops (1. short duration plant cane/1st ratoon/2nd ratoon; 2. short duration plant cane/1st ratoon/finger millet/cotton; 3. finger millet/short duration plant cane/1st ratoon/wheat; and 4. finger millet/maize/short duration plant cane/1st ratoon). These rotations were compared with the conventional duration (12 months) sugarcane crop sequence (one plant + one ratoon) in a cycle of 24 months.Soil available nitrogen (SAN) declined when 100 or 150 kg N ha^–1 was applied in the short duration sugarcane based systems, but was either maintained or improved at a higher N application rates (200 or 250 kg ha^–1). The conventional system showed a sharp decline in SAN of about 14% from its original status at the end of the sequence. Close row spacing (60 cm) of sugarcane improved the soil N level over that in the conventionally spaced rows (90 cm) probably through greater rhizosphere biomass additions.Available P declined sharply from its original level in the soil in sequence 2, the decline being marked after cotton. In all the other short duration based sequences it was maintained. The conventional system also showed reduced soil available P at the end of the sequence. Soil available K declined in all crop sequences.Nitrogen uptake was far less than additions made by fertilizer. The actual soil N balance was much lower than the expected balance thus indicating large losses of N from the soil. Phosphorus removal was also less than the additions made and thus there were improvements in the soil available P status at the end of the crop cycle. In all the sequences, there was a negative potassium balance due to greater removal by the various crops when compared to K additions. However, in the system as a whole there were net gains of K as larger amounts were recovered than had been added.     

The sequential normal scores transformation

The sequential analysis of series often requires nonparametric procedures, where the most powerful ones frequently use rank transformations. Reranking the data sequence after each new observation can become too intensive computationally. This led to the idea of sequential ranks, where only the most recent observation is ranked. However, difficulties finding, or approximating, the null distribution of the statistics may have contributed to the lack of popularity of these methods. In this article, we propose transforming the sequential ranks into sequential normal scores that are independent and asymptotically standard normal random variables. Thus, original methods based on the normality assumption may be used.

A novel approach permits the inclusion of a priori information in the form of quantiles. It is developed as a strategy to increase the sensitivity of the scoring statistic. The result is a powerful convenient method to analyze non normal data sequences. Also, four variations of sequential normal scores are presented using examples from the literature. Researchers and practitioners might find this approach useful to develop nonparametric procedures to address new problems extending the use of parametric procedures when distributional assumptions are not met. These methods are especially useful with large data streams where efficient computational methods are required.     

三氯化磷生产装置的技术改造及运行总结

介绍了三氯化磷产品的运行状况.采用黄磷与氯气直接氯化法生产三氯化磷,对不合理工艺过程进行技术改造,总结了日常生产的控制措施.     

磷酸酯中结合磷与无机磷的分析测定

将试样在硝酸、硫酸、高氯酸中分解 ,用钒钼酸铵法以 72 1型分光光度计测定阴离子表面活性剂磷酸酯中的无机磷、结合磷的质量。     

黄磷氧化制五氧化二磷危险性分析与预防

黄磷氧化制五氧化二磷属危险化学品生产,生产过程中可能发生火灾、中毒和灼伤等生产事故。运用预先危险性分析法(PHA)对五氧化二磷生产过程的潜在危险性进行辨识,并对主要危险、有害因素进行分级、分类。根据辨识与分析结果,提出相应的措施,以提高企业安全生产管理水平,预防事故的发生。     

热法磷酸塔内流动与燃烧过程的数值模拟

在全面考虑燃磷塔内燃的燃烧、湍流流动及辐射传热等物理机制的基础上,给出了燃烧塔内磷燃烧过程的数学模型和数值模拟方法。针对云南省磷化工中试基地所提供的燃磷塔的设计结构,进行了磷燃烧过程的数值模拟;模拟结果给出了燃磷塔内的速度场、温度场和各组分浓度场,所预报的壁面热流值与现场试验结果符合较好。