Very high applications of nitrogen fertilizer on grassland and residual effects in the following season

At very high nitrogen applications (480 and more kg N ha^–1 yr^–1) in field trials on all-grass swards the amount of N applied exceeded the amount of N harvested. In the humid temperate climate of the Netherlands in the subsequent spring approximately 25, 40, and 50% of this excess nitrogen was recovered as accumulated mineral nitrogen in the 0–100 cm layer of sandy, clay and heavy clay soil, respectively. The effect of this excess nitrogen on growth during the subsequent season was measured through the increase in DM and N yield over a reference treatment. In this season all treatments received a uniform application (40 kg N ha^–1 cut^–1). Residual effects were absent on sandy soil but distinct on the clay soils. On the clay soils each accumulated kg soil mineral nitrogen produced 15 kg DM. Assuming a relatively small contribution of residual nitrogen carried over in stubble, roots and organic matter, the accumulated soil mineral nitrogen would seem to be as effective as applied fertilizer nitrogen.     

包装袋上不准标明中微量元素含量不利于平衡施肥的推广

GB15 0 6 32 0 0 1复混肥标准中明确中微量元素不在包装容器和质量证明书上标明。论述该规定不利于平衡施肥技术的推广。中微量元素不计价给销售带来困难 ;标出中微量肥 ,可让农民选择更适合作物、土壤的复合肥品种 ;我们的法规应更严谨     

Ontogeny and Environment as Determinants of the Secondary Chemistry of Three Species of White Birch

This study investigates variation in the secondary chemistry of the bark of three closely related, winter-dormant species of white birch (Betula resinifera, B. pendula, and B. platyphylla) at different ontogenetic stages by using different plant parts (top and base). The experimental birches were grown for 4 years in two growing conditions (pot and field) at different nutrient levels. There was considerable species-specific quantitative and qualitative variation in the secondary chemicals in bark, but this was also affected by fertilization and the age of the plant. In general, there was greater chemical diversity in saplings than in seedlings. The study revealed three new components, secoisolariciresinol 9-O-β-glucopyranoside and two of its derivatives, that have not been reported previously for the bark of white birches. Principal component analysis showed that the species studied had a similar chemical composition at the juvenile stage, but as the plants grew, they became more clearly differentiated, which indicates that the species of older plants can be identified by chemotaxonomy. Evidently, the secondary chemistry of birches is under genetic control, but it is affected by properties of growing conditions and ontogeny. Electronic Supplementary Material Supplementary material to this paper is available in electronic form at     

开展农化服务 实施平衡施肥 促进无公害农业的发展

化肥是作物的营养,合理施用化肥,可以显著提高作物产量,改善农产品品质,保护生态环境,促进无公害农业健康发展.化肥企业要生产优质化肥产品,和农业部门一起通过深入开展农化服务工作,引导农民正确认识和施用化肥产品.     

桥梁钻孔灌注桩施工中高温冻土地基温度场动态监测与研究

通过对钻孔灌注桩地基温度变化进程进行为期 1 a 的监测,掌握了施工扰动下高温冻土地基温度场的变化规律。研究结果表明,采用冲击钻成孔工艺的混凝土灌注桩施工,对地基温度场的热扰动较大;寒季大气降温仅对浅层地基具有直接冷冻作用,而发生在深层自下而上冻结过程和桩侧土体由外向内的冻结过程却十分缓慢,温度降低幅度有限。高温多年冻土地段钻孔灌注桩群桩基础周围土体的温度,在有限的施工期内不能回冻到初始温度状况。     

黄土地基中超长钻孔灌注桩荷载传递性状研究

通过对黄土地基中 4根长短不同的超长钻孔灌注桩竖向承载力的静载试验和桩身轴向应变测试 ,分析了不同桩长的桩轴力传递规律和侧摩阻力发挥特性 ,探讨了黄土地基中超长钻孔灌注桩荷载传递性状     

广州锦城花园高层住宅的设计

结合一栋带结构转换的高层住宅建筑结构的设计 ,着重讨论了其内力分析、计算模型的处理、基础选型及计算和相应的构造措施 ,以供设计参考。     

磷酸一铵在石灰性土壤上的肥效及施用技术

分析了磷酸一铵在石灰性土壤上肥效较高的机理，以及磷酸一铵掺合尿素为较佳配方的理论根据；总结了磷酸一铵掺混其它氮钾肥料用于主要粮食、经济作物的用量及比例。     

建筑工程验槽施工技术研究

本文根据作者多年的实践经验，针对建筑工程验槽的意义、建筑工程验槽施工工序、基槽的局部处理进行探讨，以供读者参考。     

Effects of fertilization and other agronomic measures on nutritional quality of crops

Crops, as the basic source of essential substances and nutrients, do not always contain sufficient amounts of these essential nutrients to meet dietary requirements. In this review paper, we discussed the effects of fertilization and other agronomic measures on the nutritional quality of cereal, oilseed and protein crops, tuber plants and vegetables. Research indicates that application of N, P, K and S fertilizers generally increases crop yield as well as nutritional quality. For example, fertilizer increased protein concentration in cereals and pulses, oil concentration in oilseed crops, starch concentration in tubers, and concentration of essential amino acids and vitamins in vegetables. However, excessive fertilizer application, especially N fertilizer, can result in undesirable changes such as increases in nitrate, titratable acidity and acid to sugar ratio, while decreasing the concentration of vitamin C, soluble sugar, soluble solids, and Mg and Ca in some crops. Other agronomic measures, such as tillage and crop rotation, organic farming, soil moisture management, and crop breeding and genetic engineering can also have a large effect on food crop quality, though the potential benefits of these measures for improving crop quality has not been fully exploited. Research literature on this subject suggests that more information is needed in order to achieve an increase in the concentration of essential microelements, prevent accumulation of toxic levels of elements such as Cu, Mo, Zn, Ni, Se and nitrate, and other dangerous or toxic substances and elements in crops. Copyright © 2007 Society of Chemical Industry