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991.
992.
Comparison of single and coastal superphosphate for subterranean clover on phosphorus leaching soils
Coastal superphosphate, a partially acidulated rock phosphate (PARP), is being considered as an alternative fertilizer to single superphosphate for pastures in high rainfall (> 800 mm annual average) areas of south-western Australia. The effectiveness of single and coastal superphosphate, as P fertilizers, was measured in two field experiments using dry herbage yield of subterranean clover (Trifolium subterraneum). The experiments were started in April 1990 and were terminated at the end of 1993. In the years after P applications, soil samples were collected each January to measure Colwell soil-test P, which was related to plant yields measured later on that year, to provide soil P test calibrations.Relative to freshly-applied single superphosphate, the effectiveness of freshly-applied coastal superphosphate and the residues of previously-applied single and coastal superphosphate were less effective in some years (from 3% as effective to equally effective), and up to 100% more effective in other years. This large range in effectiveness values in different years is attributed to different climatic conditions. Soil P test calibrations were different for soils treated with single or coastal superphosphate. The calibrations were also different for different yield assessments (harvests) in the same year, and in different years. Consequently soil P testing can only provide a very crude estimate of the current P status of the soils. 相似文献
993.
Sluijsmans and Kolenbrander developed a simple model to describe the availability of animal manure, assuming a readily available, an easily decomposable and a slowly decomposable N fraction. We tested this model on data from an experiment in which farmyard manure had been applied for eleven successive years to silage maize [Zea mays L.] grown on a light sandy soil. The residual effects of this FYM were then measured by growing Italian ryegrass [Lolium multiflorum Lamk.] in the 12th year. The measured uptake of N by the grass of the FYM residues was then compared with the computed values. The measured amounts of N taken up agreed fairly well with the calculated amounts for applications of 50 and 100 t FYM per ha per year.If the rates of manure application are adjusted to crop requirement, the model shows that the potential, long-term release of N from the residual N fraction of FYM will not exceed 20 kg N per ha. For cattle slurry with a smaller residual fraction, the release will be at most 10% of the total annual N application. 相似文献
994.
995.
为给目前国内A型地铁车辆的舒适度设计提供理论参考,针对地铁车辆静压风道结构特点,基于k-ε两方程湍流模型和SIMPLE算法,建立包含空调送风风道和客室的三维计算模型.对计算模型的空气流动和传热状况进行CFD数值计算.计算过程综合考虑车体壁面传热和人体散热等多种传热.分析计算结果得到客室内温度场和速度场的分布规律,并对空调通风设计方案进行量化评估.计算结果表明:客室内人体头部区域温度场分布均匀,平均温度为26.6℃,最大温差为6℃;车厢内有较理想的气流组织形式,速度分布范围为0.50~0.79 m/s,而且客室端部和中部区域人体头部周围速度较大.将计算结果与欧洲EN 14750-1标准进行对比分析,认为乘客的舒适性较好. 相似文献
996.
997.
17.2%苄.哌可湿性粉剂是近年推出的稻田复配除草剂新品种。通过药剂不同用量、时间试验结果,表明亩用200-250克,在直接稻播后当天至5天内,对水37.5公斤,喷雾处理,对杂草株、鲜重防效均达90%以上,基本达到施药一次,控制草害。药剂对水稻安全,无药害产生,因而是目前直播稻田比较理想的除草剂新品种。 相似文献
998.
Downham MC Hall DR Chamberlain DJ Cork A Farman DI Tamò M Dahounto D Datinon B Adetonah S 《Journal of chemical ecology》2003,29(4):989-1011
The legume podborer, Maruca vitrata (syn. M. testulalis) (F.) (Lepidoptera: Pyralidae) is a pantropical pest of legume crops. Sex pheromone was collected by gland extraction or trapping of volatiles from virgin female moths originating in India, West Africa, or Taiwan. Analysis by GC-EAG and GC-MS confirmed previously published findings that (E,E)-10,12- hexadecadienal is the most abundant EAG-active component with 2–5% of (E,E)-10,12-hexadecadienol also present. At least one other EAG response was detected at retention times typical of monounsaturated hexadecenals or tetradecenyl acetates, but neither could be detected by GC-MS. Laboratory wind-tunnel bioassays and a field bioassay of blends of (E,E)-10,12-hexadecadienal with (E,E)-10,12-hexadecadienol and a range of monounsaturated hexadecenal and tetradecenyl acetate isomers indicated greatest attraction of males was to those including (E,E)-10,12-hexadecadienol and (E)-10-hexadecenal as minor components. In subsequent trapping experiments in cowpea fields in Benin, traps baited with a three-component blend of (E,E)-10,12-hexadecadienal and these two minor components in a 100:5:5 ratio caught significantly more males than traps baited with the major component alone, either two-component blend, or virgin female moths. Further blend optimization experiments did not produce a more attractive blend. No significant differences in catches were found between traps baited with polyethylene vials or rubber septa, or between lures containing 0.01 and 0.1 mg of synthetic pheromone. Significant numbers of female M. vitrata moths, up to 50% of total catches, were trapped with synthetic blends but not with virgin females. At present there is no clear explanation for this almost unprecedented finding, but the phenomenon may improve the predictive power of traps for population monitoring. 相似文献
999.
水煤浆在燃油热水锅炉内的燃烧试验 总被引:3,自引:0,他引:3
主要介绍了7MW燃油热水锅炉改烧水煤浆的改造设计,水煤浆炉前系统的调试,锅炉改造后的调试和水煤浆燃烧试验的结果。 相似文献
1000.
耐候性有机涂层加速老化试验研究进展 总被引:12,自引:0,他引:12
对引起涂层老化的主要因素及加速老化试验设计原则进行了介绍。在此基础上,综述了现有的涂层加速老化试验及其特点,指出涂层加速老化试验研究中存在的问题,探讨了解决方法,对涂层加速试验研究的将来进行了展望。 相似文献