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61.
模拟试验结果表明,每公斤红色石灰土中积累水泥厂粉尘在38.0克以下,土壤性状无明显恶化,且对水稻秧苗生长有促进作用。每公斤土壤合粉尘达60.8克时,始见对秧苗生长有不良影响。水泥厂降尘附着于叶面,各种降尘量下秧苗生长均受到不同程度的抑制。 相似文献
62.
铁氧化物是土壤团聚体重要的胶结物质,其主要存在于土壤黏粒中。为探索紫云英还田并配施化肥下土壤团聚体中铁氧化物的变化规律及其在不同粒级黏粒组分中的富集特点,以湖南省南县长期紫云英还田的水稻土为研究对象,选择单施紫云英(MV)、单施化肥(F100)、紫云英配施全量化肥(MV+F100)和紫云英配施80%化肥(MV+F80)4个处理,通过湿筛和离心分离土壤团聚体(>250、53~250 和2~53 μm)和黏粒(<2 μm),测定不同处理土壤团聚体及其黏粒中铁氧化物的含量,并分析它们与团聚体稳定性的关系。结果表明:(1)与MV和F100相比,紫云英与全量化肥配施增加了>250 μm粒级团聚体的含量,降低了53~250 μm粒级团聚体含量,团聚体平均重量直径(MWD)和几何平均直径(GMD)分别提高了8.2%~20.5%和4.1%~8.5%。(2)与MV相比,紫云英与化肥配施显著提高了各粒级团聚体、2~53 μm团聚体黏粒和自由态黏粒非晶质铁的含量(12.7%~55.6%,52.4%~54.9%和45.9%~48.6%),降低了>250和53~250 μm团聚体非晶质铁的富集率(32.8%~36.8%和17.2%~28.4%)。而与F100相比,2~53 μm团聚体和团聚体黏粒非晶质铁的含量以及富集率均显著降低(3.5%~21.3%、29.2%~30.4%和10.9%~26.9%)。(3)>250 μm团聚体含量与团聚体黏粒的非晶质铁含量、铁的活化度呈极显著正相关,与团聚体黏粒的游离铁含量、非晶质铁的富集率呈显著正相关。团聚体的MWD和GMD与>250μm团聚体含量呈极显著正相关,而与<2 μm团聚体含量呈极显著负相关。>250、2~53 μm团聚体黏粒和自由态黏粒的游离铁是团聚体MWD和GMD最重要的影响因子。紫云英与化肥配施,能够提高团聚体黏粒铁氧化物的含量,促进>250 μm团聚体的形成,从而增强团聚体的稳定性。 相似文献
63.
《Journal of plant nutrition》2013,36(3):379-392
ABSTRACT A greenhouse experiment was conducted to determine the bioavailability of copper (Cu) in clay loam and sandy clay loam soil. Lettuce (Lactuca sativa) and spinach (Spinacia oleracea) were grown in pots for 45 d. When mature, plants were treated for 15 additional days with 0, 100, 250, 500, or 1000 mg Cu kg?1 as CuSO4·5H2O. After harvest, Cu in soils and plant tissues was determined. In soils, applied Cu raised total and EDTA-extractible Cu. Results also revealed that the amounts of Cu extracted from sandy clay loam soil (80%) were higher than those extracted from clay loam soil (70%). In plants, increasing soil Cu concentration increased plant concentration of the metal. Plant species vary in their capacity for Cu accumulation: Lettuce has a relatively higher potential for Cu uptake and translocation than does spinach. Cu accumulation also differs among plant organs. In lettuce, metal accumulation is higher in roots than in shoots, where 60% to 80% of the total Cu of the plant is located in the roots. However, in spinach, there is no significant difference in Cu content between roots and shoots. The transfer of the metal from soil to plant is higher for plants grown on sandy clay loam soil. For a given rate of applied Cu, metal content in plant tissues is higher on sandy clay loam soil due to its higher transfer coefficient (CT) from soil to plant. Nevertheless, all crops studied showed a positive linear relationship between extractible soil Cu and plant Cu. 相似文献
64.
Artur Reinhold 《Archives of Agronomy and Soil Science》2013,59(3):203-216
Two well drained pedons from deeply weathered level terrace of Madhupur Tract were studied. Silt and clay fractions were determined by pipette sampling method and sand fractions by dry sieving. The sand fraction distribution was bimodal. The pedons consisted of three weakly stratified segments. A large amount (78–95 %) of materials of these segments belonged to the suspension population during transportation. The saltation population contained 5–20 % of the sediment, whereas the traction population only 0–0.1 %. The increase of coarser material content against depth in these pedons indicate that the energy level of the transporting medium raised more and more as the phases of deposition proceeded. 相似文献
65.
66.
The soil type is a key factor influencing N(nitrogen) cycling in soil; however, gross N transformations and N_2O emission sources are still poorly understood. In this study, a laboratory ~(15)N tracing experiment was carried out at 60% WHC(water holding capacity) and 25℃ to evaluate the gross N transformation rates and N_2O emission pathways in sandy loam and silt loam soils in a semi-arid region of Heilongjiang Province, China. The results showed that the gross rates of N mineralization, immobilization, and nitrification were 3.60, 1.90, and 5.63 mg N/(kg·d) in silt loam soil, respectively, which were 3.62, 4.26, and 3.13 times those in sandy loam soil, respectively. The ratios of the gross nitrification rate to the ammonium immobilization rate(n/ia) in sandy loam soil and silt loam soil were all higher than 1.00, whereas the n/ia in sandy loam soil(4.36) was significantly higher than that in silt loam soil(3.08). This result indicated that the ability of sandy loam soil to release and conserve the available N was relatively poor in comparison with silt loam soil, and the relatively strong nitrification rate compared to the immobilization rate may lead to N loss through NO_3~– leaching. Under aerobic conditions, both nitrification and denitrification made contributions to N_2O emissions. Nitrification was the dominant pathway leading to N_2O production in soils and was responsible for 82.0% of the total emitted N_2O in sandy loam soil, which was significantly higher than that in silt loam soil(71.7%). However, the average contribution of denitrification to total N_2O production in sandy loam soil was 17.9%, which was significantly lower than that in silt loam soil(28.3%). These results are valuable for developing reasonable fertilization management and proposing effective greenhouse gas mitigation strategies in different soil types in semiarid regions. 相似文献
67.
68.
赣榆县夹谷山坡面侵蚀产沙特征及其影响因素 总被引:1,自引:1,他引:0
选取江苏省连云港夹谷山径流小区作为研究区域,以花岗片麻岩砾质砂壤土作为试验土壤,分析了近20a来6种典型土地利用方式的侵蚀产沙特性,研究了坡面侵蚀产沙特征及其影响因素。结果表明:(1)不同土地利用方式的年侵蚀产沙量均随年降雨量的增大而增大,梯田水保效益显著;(2)不同土地利用方式的年产沙量具有显著差异性,对产沙量的影响大小依次为:顺坡耕作区标准小区经济林区牧草区乔木用材林区梯田小区。在不同土地利用方式下,防止土壤流失最有效的是梯田,与之相反,顺坡耕作区水土流失量最大。(3)在不同土地利用方式下,坡面侵蚀产沙量与降雨侵蚀力均表现为幂函数关系,相关性较强,达到了极显著水平。 相似文献
69.
70.
Dynamic Monitoring of the Mud 总被引:2,自引:0,他引:2
ZHANG Shen-qiang ZHU Shou-jun LIU Yu-lan ZHANG Zhi-hao .College of Resources & Environment Northwest A & F University Yangling 《(《农业科学与技术》)编辑部》2008,(4)
[Objective] The research aimed to provide basic files and theoretical guidance for constructing sluicing-siltation dam using soil with high clay content soil.[Method] The soils of Dagou basin near Xiwu Village of Baishui County,Shaanxi Province were taken as experimental materials.pvc pipes with same height and diameter were used to construct testing model for dynamically determining settlement,shear strength,wet density of grouting bulk under 2 different grouting speeds(15 cm/d and 25 cm/d).[Result] Under different grouting speeds,general change trend was similar during grouting course.The subsidence,deformation,shear strength and wet density increased with the increase of grouting speed.Five or six days after grouting,daily displacement under 25 cm/d grouting speed was fewer than that under 15 cm/d grouting speed.[Conclusion] The increase of grouting speed could shorten the time for reaching the same subsidence,deformation,shear strength and wet density and increased displacement at the initial stage of grouting,however,with the increase of grouting time,lower grouting bulk was bad for displacement at later grouting period because it was near impermeable layer. 相似文献