Acid treatments significantly change the physical and chemical properties of red yellow soil by lowering its pH value and leaching out aluminum(Al) ions that are harmful to the growth of plants. The structure of soil...Acid treatments significantly change the physical and chemical properties of red yellow soil by lowering its pH value and leaching out aluminum(Al) ions that are harmful to the growth of plants. The structure of soil will be damaged, resulting in higher viscosity, higher water retention rate and lower air permeability of the soil. The germination rate of Chinese pine( Pinus tabulacformic Carr. ) seeds sowed in soil treated with sulphuric acid(H 2SO 4) decreased compared to that for untreated soil. The direct cause was the large amount of Al ions leached out because of low pH values(≥3.5). The added acid decreased the soil aggregation and increased the number of micro aggregates(under 250 μm in diameter). Such changes increased the soil's viscosity, which tied the pine needles to the soil after the seeds had germinated and prevented the seedlings from fully developing.展开更多
Mineral constituents and their weathering in yellow-red soils derived from granite in middle and lower reaches of the yangtze River were studied.Light minerals in fractions greater than silt contained over 80% quartz ...Mineral constituents and their weathering in yellow-red soils derived from granite in middle and lower reaches of the yangtze River were studied.Light minerals in fractions greater than silt contained over 80% quartz and feldspar,and heavy ones contained more than 60% various iron minerals and about 30% mica and bornblende.Kaolinite was the main clay mineral,the content of which was about 300-400g/kg.Quartz was weathered very weakly,Ca-feldspar was weathered over 65%,and about 25% of Na-feldspar was weathered.The vermiculitisation of mica was relativly obvious,>50% of mica being eathered to vermiculite.Weatherable minerals were also obviously eathered,the weathering being about 60%.Soil vermiculite was evolved through the process of mica→hydromica→vermiculite-chlorite→vermiculite,which was closely related to leaching situation and oxidic condition.展开更多
Base saturation percentage (BSP) is an important soil chemical index in soil fertility and soil taxonomy. However, it is still unclear what exchangeable cation dominates BSP of soil in south China. Therefore, in this ...Base saturation percentage (BSP) is an important soil chemical index in soil fertility and soil taxonomy. However, it is still unclear what exchangeable cation dominates BSP of soil in south China. Therefore, in this study, the data of BSPs and exchangeable H+, Al3+, Ca2+, Mg2+, K+ and Na+ of 109 and 45 horizon samples of 50 and 28 soil species in red soil and yellow soil groups in the Database of Chinese Soil Species were used to explore further the characteristics of BSPs and exchangeable cations as well as the correlation between BSPs and exchangeable cations. The results showed that the concentrations of exchangeable cations in both red soil and yellow soil groups were in an order of Al3+ (4.55 ± 1.47 and 4.22 ± 1.2 cmol(+)/kg) > Ca2+ (0.32 ± 0.21 and 0.36 ± 0.24 cmol(+)/kg) > H+ (0.23 ± 0.13 and 0.19 ± 0.10 cmol(+)/kg) > K+ (0.16 ± 0.09 and 0.16 ± 0.11 cmol(+)/kg) > Mg2+ (0.13 ± 0.09 and 0.11 ± 0.08 cmol(+)/kg) > Na+ (0.08 ± 0.06 and 0.11 ± 0.06 cmol(+)/kg). For red soil group, Al3+ concentration was significantly higher than those of other exchangeable cations, Ca2+ and H+ concentrations were significantly higher than those of K+, Mg2+ and Na+;while for yellow soil group, Ca2+, H+ and K+ concentrations were significantly higher than those of Mg2+ and K+. BSP of red soil group was codetermined by Ca2+, Al3+, Mg2+ and Na+, with the contributions of 33.81%, 19.82% and 14.49%, respectively;while BSP of yellow soil group was codetermined by Al3+, Ca2+, Mg2+, K+ and Na+, with the contributions of 24.91%, 21.55%, 19.91% and 14.21%, respectively. A higher concentration of exchangeable cation does not mean the higher importance of the cation to soil BSP.展开更多
针对南方红黄壤的理化性质,基于EDEM软件选取Hertz-Mindlin with JKR模型作为红黄壤的接触模型进行参数标定,通过试验获取了红黄壤的本征参数;通过数据库确定了接触参数的取值范围;通过堆积角试验完成了红黄壤物理参数的标定。以实际堆...针对南方红黄壤的理化性质,基于EDEM软件选取Hertz-Mindlin with JKR模型作为红黄壤的接触模型进行参数标定,通过试验获取了红黄壤的本征参数;通过数据库确定了接触参数的取值范围;通过堆积角试验完成了红黄壤物理参数的标定。以实际堆积试验测得的堆积角29.5°为仿真土壤模型堆积角寻优目标,通过寻优得到最优组合参数:JKR表面能0.84 J/m^(2)、恢复系数0.32、静摩擦因数0.63、动摩擦因数0.46,该参数的仿真堆积角与试验测定堆积角误差为1.0%。利用堆积角试验的最优参数作为南方红黄壤-65Mn接触仿真过程的土壤参数,以物理穿刺试验与仿真穿刺试验对比进行红黄壤-65Mn接触参数标定,得到红黄壤-65Mn之间的接触参数:静摩擦因数0.32、滚动摩擦因数0.50、碰撞恢复系数0.20,并通过对比物理试验与仿真试验中力-位移变化曲线的拟合情况分析仿真参数可靠性,结果表明标定得到的相关参数可用于南方红黄壤的离散元仿真。展开更多
文摘Acid treatments significantly change the physical and chemical properties of red yellow soil by lowering its pH value and leaching out aluminum(Al) ions that are harmful to the growth of plants. The structure of soil will be damaged, resulting in higher viscosity, higher water retention rate and lower air permeability of the soil. The germination rate of Chinese pine( Pinus tabulacformic Carr. ) seeds sowed in soil treated with sulphuric acid(H 2SO 4) decreased compared to that for untreated soil. The direct cause was the large amount of Al ions leached out because of low pH values(≥3.5). The added acid decreased the soil aggregation and increased the number of micro aggregates(under 250 μm in diameter). Such changes increased the soil's viscosity, which tied the pine needles to the soil after the seeds had germinated and prevented the seedlings from fully developing.
文摘Mineral constituents and their weathering in yellow-red soils derived from granite in middle and lower reaches of the yangtze River were studied.Light minerals in fractions greater than silt contained over 80% quartz and feldspar,and heavy ones contained more than 60% various iron minerals and about 30% mica and bornblende.Kaolinite was the main clay mineral,the content of which was about 300-400g/kg.Quartz was weathered very weakly,Ca-feldspar was weathered over 65%,and about 25% of Na-feldspar was weathered.The vermiculitisation of mica was relativly obvious,>50% of mica being eathered to vermiculite.Weatherable minerals were also obviously eathered,the weathering being about 60%.Soil vermiculite was evolved through the process of mica→hydromica→vermiculite-chlorite→vermiculite,which was closely related to leaching situation and oxidic condition.
文摘Base saturation percentage (BSP) is an important soil chemical index in soil fertility and soil taxonomy. However, it is still unclear what exchangeable cation dominates BSP of soil in south China. Therefore, in this study, the data of BSPs and exchangeable H+, Al3+, Ca2+, Mg2+, K+ and Na+ of 109 and 45 horizon samples of 50 and 28 soil species in red soil and yellow soil groups in the Database of Chinese Soil Species were used to explore further the characteristics of BSPs and exchangeable cations as well as the correlation between BSPs and exchangeable cations. The results showed that the concentrations of exchangeable cations in both red soil and yellow soil groups were in an order of Al3+ (4.55 ± 1.47 and 4.22 ± 1.2 cmol(+)/kg) > Ca2+ (0.32 ± 0.21 and 0.36 ± 0.24 cmol(+)/kg) > H+ (0.23 ± 0.13 and 0.19 ± 0.10 cmol(+)/kg) > K+ (0.16 ± 0.09 and 0.16 ± 0.11 cmol(+)/kg) > Mg2+ (0.13 ± 0.09 and 0.11 ± 0.08 cmol(+)/kg) > Na+ (0.08 ± 0.06 and 0.11 ± 0.06 cmol(+)/kg). For red soil group, Al3+ concentration was significantly higher than those of other exchangeable cations, Ca2+ and H+ concentrations were significantly higher than those of K+, Mg2+ and Na+;while for yellow soil group, Ca2+, H+ and K+ concentrations were significantly higher than those of Mg2+ and K+. BSP of red soil group was codetermined by Ca2+, Al3+, Mg2+ and Na+, with the contributions of 33.81%, 19.82% and 14.49%, respectively;while BSP of yellow soil group was codetermined by Al3+, Ca2+, Mg2+, K+ and Na+, with the contributions of 24.91%, 21.55%, 19.91% and 14.21%, respectively. A higher concentration of exchangeable cation does not mean the higher importance of the cation to soil BSP.
文摘针对南方红黄壤的理化性质,基于EDEM软件选取Hertz-Mindlin with JKR模型作为红黄壤的接触模型进行参数标定,通过试验获取了红黄壤的本征参数;通过数据库确定了接触参数的取值范围;通过堆积角试验完成了红黄壤物理参数的标定。以实际堆积试验测得的堆积角29.5°为仿真土壤模型堆积角寻优目标,通过寻优得到最优组合参数:JKR表面能0.84 J/m^(2)、恢复系数0.32、静摩擦因数0.63、动摩擦因数0.46,该参数的仿真堆积角与试验测定堆积角误差为1.0%。利用堆积角试验的最优参数作为南方红黄壤-65Mn接触仿真过程的土壤参数,以物理穿刺试验与仿真穿刺试验对比进行红黄壤-65Mn接触参数标定,得到红黄壤-65Mn之间的接触参数:静摩擦因数0.32、滚动摩擦因数0.50、碰撞恢复系数0.20,并通过对比物理试验与仿真试验中力-位移变化曲线的拟合情况分析仿真参数可靠性,结果表明标定得到的相关参数可用于南方红黄壤的离散元仿真。
