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41.
Nguyen Van Nguu 《Nutrient Cycling in Agroecosystems》1987,14(2):135-142
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. 相似文献
42.
43.
双亚磷酸酯类抗氧剂626合成的工艺 总被引:3,自引:0,他引:3
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%。 相似文献
44.
Studies were undertaken on the isolation and identification of reaction products of ammonium nitrate phosphate (ANP) fertilizers containing 30, 50 and 70 per cent water-soluble phosphorus (WSP) of total phosphorus in representative soils of the vertisol, oxisol, alfisol, entisol, mollisol and aridisol groups of India. ANP fertilizers were applied in solid form to soil, and reaction products formed at and around the site of ANP fertilizer placement were identified after six weeks incubation in moist soils by X-ray diffraction technique. DCPD (dicalcium phosphate dihydrate- CaHPO4 · 2H2O) was the major reaction product of ANP fertilizers containing 30 and 50 per cent WSP in vertisol, entisol, aridisol, mollisol, oxisol and alfisol, and of ANP containing 70 per cent WSP in vertisol, entisol, alfisol, aridisol and mollisol. DCP (dicalcium phosphate-CaHPO4) was detected with ANP of 30 and 50 per cent WSP in the vertisol, alfisol, entisol, mollisol and aridisol groups of soils. In addition to DCPD, FePO4 · 2H2O (metastrengite) and AlPO4 · 2H2 O-monoclinic (metavariscite) were formed in alfisol and oxisol soils with ANP of 30 and 50 per cent WSP. FePO4 · 2H2O and AlPO4 · 2H2O (metavariscite) were identified in alfisol and oxisol soils while AlPO4 · 2H2O-orthorhombic (variscite) was formed in alfisol soils with ANP of 70 per cent WSP. 相似文献
45.
根据不同成分的水样中细菌再生长情况,研究了水中磷对生物稳定性的限制因子作用。结果显示,在测试水样中添加1 mg/L的NaAc后,细菌总数增加了100%-187%;在水样中添加15μg/L的NaH2PO4后,细菌总数增加了180%-203%。随水样中PO43-P含量的增加,细菌数目也在逐渐增加,但当水中PO43-P的含量大于等于5μg/L时,细菌已无明显增长趋势。试验结果表明磷和碳一样也是水中微生物生长的限制因素之一,并且对于该水样当PO43-P的含量为2μg/L—5μg/L之间的某个值时,磷的限制作用将会表现出来。 相似文献
46.
47.
T. Kanerva V. Kröger K. Rahkamaa-Tolonen M. Vippola T. Lepistö R. L. Keiski 《Topics in Catalysis》2007,45(1-4):137-142
Laboratory-scale ageing and poisoning procedures were performed on selected diesel catalysts. The results showed that phosphorus
poisoning together with high temperature ageing has a strong effect on the catalytic activity and microstructure of platinum
containing catalysts. Phosphorus poisoning contaminated the catalysts resulting in phosphate formation, e.g. CePO4 and AlPO4. Poisoning and air ageing increased platinum particle-size and washcoat grain-size. 相似文献
48.
P. R. Ernani 《Nutrient Cycling in Agroecosystems》1995,45(3):193-197
The electrolyte concentration of the soil solution affects the availability of some nutrients in the soil, especially of P, but it is not know at what salt concentration the reactions start to be significantly affected and their magnitude. This study was carried out to evaluate the effect of rates of potassium chloride (KCl) on some soil parameters that determine supplying of P, K, Ca, Mg, and Al in an unlimed acid soil. Increasing rates of KCl (from zero up to 2000 mg K kg–1) were applied to soil samples fertilized with 360 mg P kg–1. Solution (Cli) and exchangeable (Csi) forms of P, Ca, Mg, K, and Al were determined in the treated soil samples after 30-days of incubation; cation activity in solution and their selectivity coefficients were then calculated. Addition of KCl at rates equal to or above 500 mg K kg–1 caused a large relative increase on P in the soil solution (Pli) but a small and insignificant increase on the absolute value of Pli. All forms of soil K increased with increases on K applied, and buffer power for K varied according to the range of soil K. At all KCl rates, K displaced Ca, Mg, and Al from the solid phase to the soil solution, but had no effect on the extractable values. The relative preference of cations for the adsorption sites increased with increase on cation valency, and only those selectivity coefficients involving K were affected by K applied. 相似文献
49.
D. M. Weaver 《Nutrient Cycling in Agroecosystems》1993,36(2):165-170
Nutrient loss from rural point sources and urban environments need to be minimised as part of strategies to overcome declining water quality on the Swan Coastal Plain and in the Peel-Harvey estuary in Western Australia. This paper discusses the management of nutrient losses from domestic effluent, urban stormwater runoff, domestic gardens and public open space, intensive animal industries and intensive irrigated agriculture. Measures to minimise nutrient losses from these sources are outlined, using cooperative, technological and regulatory approaches. 相似文献
50.
介绍了国内外精细磷化工的生产现状,分析了我国发展磷酸盐的产品领域和市场前景,对基础产品、市场营销、技术创新、大型企业进入磷酸盐行业提出了建议。 相似文献