不同筛分方法对土壤干团聚体粒径分布的影响研究

发布时间：2018-01-20 04:44

  本文关键词： 平筛 旋筛 土壤可蚀性 土壤干团聚体指标 土壤风蚀度　出处：《河北师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：土壤风蚀是风对地表土壤的侵蚀、搬运、堆积的过程。土壤风蚀破坏地表,造成土壤营养物质损失,导致土地荒漠化。土壤可蚀性是土壤风蚀研究的重要方面,土壤干团聚体是影响土壤可蚀性的重要参数,其组成结构和基本特性是决定土壤侵蚀、压实、板结等物理过程与作用的关键指标之一,同时也是土壤肥力的基础和评价土壤质量的重要指标。通过对土壤风蚀度(EF)、平均几何直径(GMD)、平均质量直径(MWD)、分形维数D的分析,可以进一步阐明干团聚体特征间接量化土壤可蚀性,而根据平筛和旋筛两种筛分方式对干团聚体指标影响的研究并不多见。因此,本文选取河北坝上康保县境内四种地类(草地、林地、留茬地、翻耕地)74个土壤样品,对土壤样品进行平筛、旋筛筛分和土壤理化性质处理,比较土壤干团聚体粒径分布,从而探究平筛和旋筛对于土壤干团聚体指标以及土壤机械组成的影响,不同土地利用方式间的干团聚体指标差异,进而评价本区域内土壤可蚀性现状等,研究结果表明:(1)通过对平筛、旋筛所得出的土壤粒度组成进行Mann-Whitney U检验的差异性分析发现,平筛和旋筛以0.84mm粒级为分异界限,小粒级(0.84-0.5mm、0.5mm)处差异性不显著,在大粒级(20mm、20-5mm、5-2mm、2-0.84mm)差异性显著,呈现出大粒级的土壤颗粒差异性显著,而小粒级不显著的现象。由于该地区砾石含量较高和平筛的震荡作用中砾石打散较大团聚体,一定程度上影响土壤机械组成,粒径较大的土壤颗粒被破碎后造成可蚀性颗粒有所增多,呈现出随EF值降低差异增大的趋势,使平筛的EF值高于旋筛。同时0.84mm(0.84-0.5mm、0.5mm)粒级差异性不显著也是平筛与旋筛EF差异性不显著的原因。(2)通过对GMD、WMD、D干团聚体指标进行二元相关性分析和Mann-Whitney U检验差异性分析,在平筛、旋筛团聚体指标二元相关性分析中,GMD、WMD、D、EF都呈现极显著正相关;D、EF指标差异性不显著,EF(0.84mm)差异性不显著符合粒度组成分析中的结论,而差异性分析中GMD、WMD指标差异性显著,同时在相关性分析的1:1线图中呈现出平筛GMD、WMD的值普遍高于旋筛,平筛和旋筛的GMD、WMD指标同大粒级(20mm、20-5mm、5-2mm)土壤粒度组成均为极显著正相关,同小粒级(0.5mm)均为极显著负相关,由于砾石可能打散大粒级的土壤颗粒,增加了2-0.84mm粒级不可蚀土壤颗粒,土壤抗蚀性增强,从而使得平筛GMD、WMD指标的值高于旋筛。(3)平筛和旋筛的分形维数D与小粒级(0.5mm)均为极显著正相关,同大粒级(20mm、20-5mm、5-2mm、2-0.84mm)均为极显著负相关,并且平筛和旋筛的D显著正相关但差异性不显著。平筛和旋筛的GMD、WMD之间差异性显著,并呈现平筛大于旋筛的情况;D在不同地类均与砾石含量呈现显著负相关,而GMD与WMD指标只在林地地类中与砾石含量存在显著相关性,D与不同粒级的相关性分析中同样优于GMD、WMD,因此,D在表征不同地类土壤的粒度组成的能力强于GMD、WMD指标,分形维数D对于表征土壤可蚀性和土壤风蚀状况相较于GMD、WMD更为稳定,另外,发现分形维数D对于小粒级描述更为敏感,而GMD、WMD指标对于土壤的大粒级更为敏感。(4)在不同地类的土壤团聚体指标均值分析中,林地在平筛和旋筛均为抗蚀性最强的地类,其GMD、WMD均值最高,D、EF均值最低。留茬地抗蚀性优于翻耕地,留茬地EF低于翻耕地,且GMD、WMD高于翻耕地,D小于留茬地。农田防护林和耕地留茬作为坝上地区的主要防风蚀手段具有明显抗蚀效果,生态效益明显。(5)平筛、旋筛作为筛分土壤粒度组成的先行步骤对于土壤风蚀研究产生基础性影响,其对于土壤粒度组成的影响将会进一步影响土壤干团聚体指标,本文对于平筛的GMD、WMD值高于旋筛,在土壤机械组成的大粒级(20mm、20-5mm、5-2mm、2-0.84mm)差异性显著的情况进行了分析,对于砾石含量较高的风蚀区的土壤使用平筛筛分有可能产生误差;GMD、WMD、D、EF之间的相关性分析中,平筛和旋筛保持了各指标间相关性分析的一致性,但旋筛的相关性系数均高于平筛,旋筛的相关性均优于平筛。因此,旋筛相较于平筛对于土壤筛分和土壤粒度还原具有一定的优越性。(6)通过EF、GMD、WMD、D与土壤理化性质、土壤机械组成的相关性分析中发现,研究区EF、D与砾石含量在各地类均为显著相关,土壤抗蚀性指标更多的受到砾石含量较高的影响。有机质、碳酸钙与EF、GMD、WMD干团聚体指标在林地、留茬地、翻耕地中的相关性较差。草地地类中各团聚体指标与有机质相关性较好,有机质与粘粒有利于草地中土壤团聚体形成。翻耕地和留茬地由于受到耕作制度、农田分散管理的影响、林地由于受到防护力种植株距、走向、树龄、树种等影响,以及长期的风蚀导致有机质含量较低,使土壤GMD、WMD、D、EF与有机质、碳酸钙、粘粒、砂粒指标在林地、留茬地、翻耕地中无相关性。因此,较高的砾石含量会对不同筛分方式的土壤机械组成造成影响,而风蚀区由于长期遭受风蚀,砾石含量普遍较一般土壤高,同时土壤有机质含量较低,会导致土壤干团聚体指标的差异,对表征土壤可蚀性造成影响。
[Abstract]:Soil erosion is the wind erosion on the surface of the soil, handling, stacking process. Soil erosion destroy the surface, resulting in soil nutrient loss, resulting in land desertification. Soil erodibility is an important aspect of soil erosion, soil dry aggregate is the influence of soil erodibility of the important parameters, the structure and basic characteristics is to determine the soil erosion, compaction, compaction index is one of the key physical processes and function, but also the basis of soil fertility and soil quality assessment is an important indicator. The soil erosion degree (EF), geometric mean diameter (GMD), mean weight diameter (MWD), analysis of the fractal dimension D, can further clarify dry aggregate characteristics of indirect quantification of soil erodibility, and based on the flat screen and rotating screen two screening methods on dry aggregate index is rare. Therefore, this paper selects the Hebei dam in Kangbao County land four Class (grassland, woodland, stubble, farmland) of 74 soil samples, soil samples on the flat screen, rotary screen and soil physicochemical properties, soil dry aggregates, so as to probe into the flat screen and rotating screen effects on soil dry aggregate index and soil mechanical composition, aggregate index the difference between the stem of different land use patterns, and to evaluate the regional soil erosion status, the results of the study show that: (1) based on the flat screen, rotary screen the soil particle size composition of Mann-Whitney U test analysis on the difference of the flat screen and rotating screen with 0.84mm size difference line of small size (0.84-0.5mm, 0.5mm). The difference is not significant, in large size (20mm, 20-5mm, 5-2mm, 2-0.84mm) showed significant difference, the difference of soil particle size was large, and the small size is not significant. The phenomenon of gravel content and higher in the area The shock effect of flat screen in scattered gravel aggregates, have a certain effect on the soil mechanical composition, particle size of larger particles were broken by soil erodibility particles increased, decreased with increasing the difference of the EF value, the EF value is higher than the flat screen, rotary screen. At the same time 0.84mm (0.84-0.5mm, 0.5mm) no significant differences in size is also flat screen and rotating screen EF had not significant difference. (2) based on GMD, WMD, D index analysis of dry aggregates two yuan Mann-Whitney correlation analysis and U test the difference, in flat screen, aggregate index of two yuan in correlation analysis, rotating screen GMD, WMD. D, EF showed a highly significant positive correlation; D, EF index had not significant difference, EF (0.84mm) had not significant difference with grain size analysis of the conclusion, and the difference of GMD in WMD, there were significant differences in 1:1 at the same time, correlation analysis of the line graph showing a flat screen GMD. W MD鐨勫，

本文编号：1446899