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.     

有机磷化物制备羟基磷灰石工艺条件的探讨

探索用有机磷化物制备羟基磷灰石的工艺条件：采用硝酸钙、氨水、磷酸三丁酯为原料进行正交对比研究，优化得到了制备较佳羟基磷灰石的工艺条件。优化的工艺条件为：原料中Ca／P（molar ratio）1．67；Ca（NO3）2、4H2O／NH3H2O（g／g）为0.99；烧结温度为850℃：恒温时间为5h，并对合成的样品进行了化学和红外光谱的分析。     

高产小麦磷钾效应和适宜氮磷钾配比研究

黄泛冲积石灰性土壤在适宜施氮水平下磷钾不同用量及配比对小麦生长的影响表现为:(1)磷肥以中量施用水平(每公顷施用P2O5120kg)增产效果最好,分别比未施磷、低量施用水平(每公顷用P2O548kg)增产30.82%、20.27%,高量施用水平(每公顷施用P2O5192kg),虽然比中量施用水平表现出增产,但增产幅度很小,只有2.85%;(2)钾肥对小麦的增产效应小于磷肥,只有在施用磷肥的基础上配施钾肥,才能使钾的效应得到充分发挥;(3)小麦全生育期氮磷钾施用比例1∶0.5∶0.5为最佳,每公顷施用N240kg、P2O5120kg、K2O120kg效益最高。     

基于全概率公式直接推求管运洪水

本文为保证防洪安全的前提下充分发挥水库的综合效益,提出了基于全概率公式推求管运洪水的方法,并详细阐述了其基本原理;提出了在资料较短或前、后汛期洪水特性大致相同的情况下运用全概率公式推求管运洪水的实际方法;以马边站的洪水资料进行实例研究,其结果表明基于全概率公式推算出来的管运洪水既能使水库工程达到防洪标准,又能充分发挥水库的综合效益。     

工业含磷废水除磷研究

在常温条件下，以低廉的氯化镁、碳酸氢铵作沉淀剂加入到含磷废水中除磷时，得到的一次处理液因含磷高无法达标排放。本文利用聚合氯化铝（PAC）和聚丙烯酰胺（PAM）作复合混凝剂，对其进行进一步除磷研究，实验研究证明，加入复合混凝剂的效果优于单独使用，并可使处理后的废水达到国家二类水排放标准。     

The potential use of wetlands to reduce phosphorus export from agricultural catchments

Natural and artificial wetlands have the potential to reduce phosphorus (P) loads from dispersed agricultural runoff and from point sources in the Peel-Harvey catchment, Western Australia. Small experimental systems containing wetland plants and substrate have shown significant removal of P from inflowing water, the proportion of P removed being dependent on P concentration and flow rate of water through the system. The use of artificial wetlands to treat diffuse agricultural runoff is limited by the highly seasonal runoff typical of this Mediterranean climate, while use at point sources has so far been unsuccessful because compounds from the effluent clog the wetland filters. Treatment at point sources may well be feasible after further research.Natural wetlands in the catchment absorb P received in runoff from farmland and, in the absence of any outflow channels to the drainage system, confine this P within the boundaries of the wetland. Disturbance to wetlands may reduce their efficiency in absorbing nutrients and may release P stored in the vegetation and sediment to the water. The conservation of natural wetlands is recommended to maximise nutrient retention in the catchment.     

Transformations of residual fertilizer P in a semi-arid tropical soil under eight-year peanut-wheat rotation

Long-term transformations of residual phosphorus (P) governs the availability of phosphorus to crops. Very limited information is available on the transformations of residual fertilizer P in semi-arid tropical soils under long-term crop rotations. Therefore, using sequential phosphorus fractionation procedure, we studied changes in labile and stable forms of inorganic and organic P in a semi-arid alluvial soil (Typic Ustisamments) after eight years of annual fertilizer P application either to one crop (alternate) or to both crops (cumulative) in a peanut (Arachis hypogaea) — wheat (Triticum aestivum) rotation.Total residual fertilizer P in soil (P recovered from P-fertilized minus control plots) ranged from 62 to 176 mg P kg^–1. In the alternate P treatments (P applied to peanut or wheat only), on an average of 3 rates of applied P (13, 26 and 39 kg P ha^–1), in surface (0–15 cm) and subsurface (15 to 30 cm) soil, respectively, residual fertilizer P consisted of 14.8 and 2.2% resin-P, 8.6 and 2.8% NaHCO₃-P, 6.3 and 0% microbial-P, 31.4 and 4.2% NaOH-P, 7.8 and 3.0% aggregate protected-P, 12.5 and 3.0% HCl-P, 3.4 and 0% H₂SO₄-P. The corresponding values for surface and subsurface soils of cumulative P treatments (P applied to both peanut and wheat) were: 12.8 and 1.6% resin-P, 6.9 and 2.3% NaHCO₃-P, 4.7 and 0% microbial-P, 32.5 and 4.2% NaOH-P, 5.6 and 2.0% aggregate protected-P, 14.8 and 3.8% HCl-P, 6.7 and 2.1% H₂SO₄-P. Considerable lower values for the 15–30 cm depth indicate only a very small movement of residual P to the subsoil.Significantly lower amount of fertilizer P (28% and 44%) found in labile (resin, NaHCO₃ and microbial P) and semi-labile (NaOH and sonicated NaOH P) fractions for the cumulative P treatment than alternate P treatment (35 and 46%, respectively) suggests that increased rates and frequency of applied P tend to enhance the conversion of residual P to stable forms which are less available to plants. About 12 to 19% of residual fertilizer P found as organic P in labile and semi-labile forms confirmed that organic P increased with long-term fertilizer management. In conclusion, the results of our study suggest that the alternate application of fertilizer P to a crop, as is shown for wheat, helps reduce the transformations of residual P to stable P forms.     

Effect of nitrogen,phosphorus and soil and crop residues management practices on maize (Zea mays L.) yield in ultisol of eastern Cameroon

The shortening of fallow period in several areas in tropical Africa has reduced soil fertility and exposed soils to erosion and run-off. Fertilizer application and crop conservation practices are needeed to sustain high crop yield and to conserve the natural resource base for upland crop production in the continent. Field trials were carried out to evaluate the effect of fertilizer application and soil and crop residues management practices on yield of maize (Zea mays L.) planted on a Plinthudult soil at Bertoua, Eastern Cameroon. Maize yields increased significantly with nitrogen and phosphorus fertilizer application. Under the rainfall pattern prevailing in the area, the amount of nitrogen required for maximum yield was higher in the second season. On the other hand, the amount of phosphorus required for maximum yield appeared to decrease with time. The burning of crop residues and weeds prior to planting together with no-till practive gave higher yield of maize than other soil and crop residues management practices.     

PA66阻燃改性研究

通过卤系、氮系、磷系等阻燃体系对尼龙（PA）66进行阻燃改性研究，开发出一种赤磷与无机阻燃剂共用的复配阻燃体系。结果表明，当加入 赤磷10份、无机阻燃剂10份、玻纤30份时，利用该阻燃体系阻燃的PA66，其燃烧性能达FV－0级，拉伸强度大于100MPa，缺口冲击强度大于9kJ/m^2，综合性能优良。     

双亚磷酸酯类抗氧剂626合成的工艺

摘要以新工艺合成了双（2，4-二叔丁基苯基）季戊四醇二亚磷酸酯（抗氧剂626）。先以三氯化磷与2，4-二叔丁基苯酚反应合成出中间体（2，4-二叔丁基苯基）二氯亚磷酸酯，再将其与季戊四醇反应合成出产品。探索了反应条件，溶剂及催化剂的种类等因素对产品收率和质量的影响，筛选出最佳的合成工艺条件为：以甲苯或二甲苯为熔荆，体系保持负压至常压，第一步反应温度40—50℃，反应2h，第二步反应温度50—130℃，反应6h，反应收率为86％。