东北黑土压缩特性及其影响因素的研究

发布时间：2019-02-19 09:34

【摘要】：随着科学技术的不断进步,农业机械成为农业生产中不可或缺的劳动工具。农业机械对土壤造成的负面影响已经引起国内外学者的广泛关注。本文采用室内单轴压缩试验探讨黑土在不同容重、含水量,黏粒、TOC的初始条件下的压缩特性,并研究了田间机械碾压次数对不同土层土壤物理性状的影响。研究结果如下：(1)土壤初始含水量、容重及其交互作用对黑土的先期固结压力(σp)和压缩指数(Cc)的影响是极显著的(P0.01)。先期固结压力与土壤容重呈正相关关系而与初始含水量呈现负相关关系(P0.01),其中先期固结压力容重1.5 g·cm-3较1.1 g.cm-3增幅达749.7%,含水量25%较15%降幅达36.3%。容重与压缩指数呈负相关关系(P0.05)。土壤对外界的抵抗能力随着容重的增加而增加,而随着含水量的增加而减小,且含水量越高,土壤受到外力后,更容易发生形变。(2)黏粒添加量、TOC及其交互作用对黑土土壤的先期固结压力、压缩指数均会产生显著影响(P＜0.05)；其中黏粒添加量与TOC均与σp呈显著正相关关系。黏粒与TOC含量的增加均会使黑土先期固结压力增大,其中先期固结压力黏粒添加量40%较无黏粒添加量比增幅达73.5%；高有机质含量土壤较低有机质含量土壤比增幅达158.6%；土壤TOC含量与黏粒含量越高,压缩指数越大,土壤被压缩后越容易发生形变。(3)田间机械碾压试验结果表明：对于同一土层,碾压次数与土壤容重、机械阻力成正相关关系(P0.05)；与土壤孔隙度、饱和导水率呈负相关；碾压对上层土壤影响最大,与对照相比,0-10cm土层容重最高增幅达40%,孔隙度最高降幅29.1%,各处理0-20cm土层饱和导水率的降幅均达到99%以上。同一碾压次数下随土层深度的增加,土壤物理性状的改变逐渐减小。碾压次数达到两次及以上时,碾压次数对同一土层间的机械阻力,饱和导水率的影响不明显。综上,初始容重、含水量和有机质、黏粒含量是影响供试土壤农田黑土预固结压力值和压缩指数的重要因素。土壤预固结压力值同初始容重、有机质含量、黏粒含量呈正相关关系,同初始含水量呈负相关关系。土壤压缩指数与初始容重呈负相关、与黏粒含量呈正相关关系、而与含水量关系不密切。田间机械碾压对0-30cm土壤容重、机械阻力和饱和导水率影响较大。建议在农业生产中要注意适耕期,减少农业机械碾压次数。
[Abstract]:With the continuous progress of science and technology, agricultural machinery has become an indispensable labor tool in agricultural production. The negative effects of agricultural machinery on soil have attracted wide attention of scholars at home and abroad. In this paper, the compression characteristics of black soil under the initial conditions of different bulk density, water content, clay and TOC were studied by uniaxial compression test in laboratory, and the effect of field mechanical compaction times on soil physical properties of different soil layers was studied. The results were as follows: (1) the effects of initial soil moisture content, bulk density and their interaction on the preconsolidation pressure (蟽 p) and compression index (Cc) of black soil were significant (P0.01). There was a positive correlation between preconsolidation pressure and soil bulk density and a negative correlation between preconsolidation pressure and initial water content (P0. 01). The preconsolidation pressure bulk density of 1. 5 g cm-3 was 74. 7% higher than that of 1. 1 g.cm-3. The water content of 25% is 36.3% lower than that of 15%. There was a negative correlation between bulk density and compression index (P0.05). The resistance of soil to the outside increases with the increase of bulk density, but decreases with the increase of water content, and the higher the water content is, the more easily the soil is deformed when it is subjected to external force. (2) the amount of clay added, TOC and its interaction had significant effects on the preconsolidation pressure and compression index of black soil (P < 0. 05). There was a significant positive correlation between the addition of clay and TOC and 蟽 p. The increase of clay and TOC content increased the preconsolidation pressure of black soil, and the 40% content of preconsolidation pressure clay increased 73.5% than that of non-clay. The increase of soil ratio of high organic matter content to low organic matter content was 158.6; The higher the content of TOC and clay, the greater the compression index, and the more easily the soil deformed after compression. (3) the results of field mechanical rolling test showed that: for the same soil layer, the compaction times and the bulk density of soil were increased. The mechanical resistance was positively correlated (P0.05); There was a negative correlation between soil porosity and saturated water conductivity. The effect of compaction on the upper soil was the greatest. Compared with the control, the maximum bulk density of 0-10cm soil increased by 40, the highest porosity decreased by 29.1and the saturated water conductivity of each 0-20cm soil layer decreased by more than 99%. With the increase of soil depth, the change of soil physical properties decreased gradually under the same rolling times. When the rolling times reach two or more times, the influence of rolling times on the mechanical resistance and saturated water conductivity of the same soil layer is not obvious. In conclusion, the initial bulk density, water content, organic matter content and clay content are the important factors that affect the preconsolidation pressure and compression index of the black soil. Soil preconsolidation pressure was positively correlated with initial bulk density, organic matter content and clay content, but negatively correlated with initial water content. Soil compression index was negatively correlated with initial bulk density, positively correlated with clay content, but not closely related to water content. Field mechanical compaction has a great effect on 0-30cm soil bulk density, mechanical resistance and saturated water conductivity. It is suggested that we should pay attention to the suitable tillage period and reduce the rolling times of agricultural machinery in agricultural production.
【学位授予单位】：沈阳农业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S152;S220

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