Nitrogen fertilizer use in rainfed agriculture

Agronomic efficiency (AE) is defined as the increase in economic yield of a crop per unit fertilizer applied. Components of AE are physiological efficiency and apparent recovery fraction. The latter can be further separated into uptake efficiency and availability index. Ways to increase the nitrogen fertilizer use efficiency in rainfed agriculture through fertilizer management are discussed.     

制氢装置转化催化剂失活原因分析及对策

中石化西安分公司制氢装置转化催化剂在短期生产运行过程中,因催化剂积碳导致转化炉管表面出现大面积花斑,近半数炉管出现红管,炉管差压增大,转化出口甲烷含量超标,芳烃穿透.对催化剂失活原因进行细致分析后表明:装置开停车频繁;转化催化剂多次积碳-烧碳使催化剂表面剥蚀破碎、跑损严重为主要原因.针对失活原因制定了相应对策.     

渗透汽化汽油脱硫技术研究进展

随着环保法规的日益严格,世界各国对清洁汽油中硫含量做出了严格的规定,汽油的低硫化甚至无硫化已成为一种必然趋势,汽油的深度脱硫技术已成为各石油公司和相关研究者的研究热点。渗透汽化是一种新型高效的膜分离技术,其在汽油深度脱硫技术方面具有独特优势。介绍了渗透汽化汽油脱硫技术的基本原理、工艺特点及国内外有关研究进展情况。     

Characterization of the reactivity of limestones with SO2 in a fluidized bed reactor

The reaction between SO₂ and calcined limestone particles has been studied in a fluidized bed combustor. Measurements of sorbent reactivity with SO₂ were made for small batches of limestone injected into the combustor. Simultaneous continuous combustion of bituminous coal provided conditions like those of a boiler for study of the sulphation reaction. A semi-empirical rate model of the CaO-SO₂ reaction has been developed. External mass transfer of SO₂, diffusion within the particles and chemical reaction are taken into account. The limestone reactivity with SO₂ is characterized by two parameters which are dependent on the temperature and sorbent particle size. A model for predicting the limestone requirements in a fluidized bed boiler has been developed. Parameters from the batch experiments are included. The predictions for sulfur retention agree with the experimental results. In addition, effects of operating conditions (gas velocity, recycle, limestone particle size) on the retention of SO₂ were simulated using the model.     

高浓度烤烟专用肥肥效试验

介绍高浓度烤烟专用肥肥效试验。结果表明：楚雄磷肥厂生产的高浓度烤烟肥，可以代替进口的同类化肥。     

关于有机-无机复混肥国家标准

介绍有机无机复混肥料国家标准的范围、技术要求和试验方法。     

Co-Mo-K催化剂上COS、HCN转化率的热力学分析

利用热力学基础数据和相关软件对Co-Mo-K催化剂上COS、HCN加氢和水解反应进行了热力学计算。在热力学上,COS、HCN加氢和水解反应在耐硫变换条件下均为自发过程。计算结果表明在Co-Mo-K耐硫变换条件下COS、HCN主要发生的是水解反应,该结果与工业经验数据基本一致,可以作为工业实际借鉴。     

亚砜基改性纤维素膜的SO2气体渗透性能研究

分别使用二甲基亚砜浸泡的物理方法及苯基乙烯基亚砜加成的化学方法对纤维素膜进行了改性,并对改性膜的性能进行了测试.结果表明改性后纤维素膜仍为致密结构,SO2的渗透性能及其对N2的分离性能明显提高,其中改性液中添加二甲基亚砜的均相化学加成反应所得的改性膜具有较好的SO2渗透稳定性.     

Phosphate availability in calcareous Vertisols and Inceptisols in relation to fertilizer type and soil properties

The availability to plants of fertilizer phosphorus (P) applied to soil, as measured by chemical extraction, is used to estimate P fertilizer needs. We studied the availability of P, applied as monocalcium phosphate (MCP) powder, ordinary superphosphate (OSP) granules and diammonium phosphate (DAP) granules in 24 calcareous Vertisols and Inceptisols of Andalusia, Spain, by using laboratory incubation techniques. The soils differed widely in their P adsorption- and Ca-phosphate precipitation-related properties. For MCP, availability (defined as the proportion of added P that is recovered by extraction with NaHCO₃ or is isotopically exchangeable) decreased markedly with incubation time and increasing addition rate. The mean recoveries after 180 d of incubation at field capacity at a rate of 246 mg P kg^–1 soil were 17% for Olsen P, 38% for Colwell P, and 16% for isotopically exchangeable P (IEP). Increasing the application rate to 2460 mg kg^–1 resulted in recoveries of 6% for Olsen P, 25% for Colwell P, and 4% for IEP. While IEP-based recovery was not significantly correlated to any soil property, that based on Olsen P (and, to a lesser extent, Colwell P) decreased sharply with increase in the ratio of clay (or Fe oxides) to total (or active) calcium carbonate equivalent. Accordingly, Olsen P might overestimate P availability in those soils relatively rich in carbonate and poor in clay and Fe oxides. On the other hand, recovery of applied P from soils containing more clay and Fe oxides, by a sequential extraction (with H₂O, two 0.5M NaHCO₃ treatments, 0.5M HCl), was lower than 100%, thereby suggesting phosphate occlusion by Fe oxides or clay.Availability of the fertilizers tested 90 d after application was found to decrease in the following order: MCP powder (rate, 246 mg kg^–1) > DAP granules (rate, 547 mg kg^–1) > MCP powder (rate, 738 mg kg^–1) > OSP granules (rate, 308 mg kg^–1). Differences between fertilizers tended to increase with increasing carbonate content in the soil. This may have been due to precipitation of Ca phosphates caused by the presence of Ca in the fertilizer and the high Ca- supplying capacity of the more calcareous soils.     

Effect of excess boron fertilization on status and availability of boron in calcareous soils

Field experiments were conducted at Al-Qatif area in the eastern region of Saudi Arabia to study the status and availability of B under B fertilization regime in three types of calcareous soils and to evaluate the response of two alfalfa varieties, Hassawi (local variety) and Hyden (american variety), to increasing levels of added B.Boron was applied at 7 rates as Na₂B₄O₇.10H₂O. Four cuttings were taken from each site at different intervals. Data showed that extractable B by hot-water and NH₄HCO₃-DTPA (8 days after borax application) was significantly (p <0.001) affected by soil type and B applications. The amount of B recovered by hot-water from the three soils, 200 days after borax application, was in the following order: sandy loam > sandy clay loam > clay loam.Total dry matter of alfalfa (4 cuttings) was significantly (p <0.05) affected by soil type, borax application rates and alfalfa variety.The critical level of B in plant as determined by Cate and Nelson analysis, ranged from 148 to 652 mg kg^–1 dry matter for Hassawi cultivar and 138 to 521 mg kg^–1 for Hyden cultivar in the first harvest. However, the upper critical levels for the 2nd, 3rd and 4th harvests were 800, 875 and 935 mg B kg^–1 dry matter for Hassawi and 603, 723 and 812 mg B kg^–1 for Hyden varieties, respectively. Nevertheless, the lower critical levels for 2nd, 3rd and 4th harvests ranged from 148 to 153 mg B kg^–1 dry matter for Hassawi and 138 to 142 mg B kg^–1 for Hyden.