不同胶结剂的黄绵土团聚作用特征研究

发布时间：2018-09-14 18:05

【摘要】：本研究选用黄土高原典型土壤黄绵土,利用PAM、腐殖酸、壳聚糖、硫酸铝4种不同的土壤胶结剂,对不同胶结剂含量下的不同粒径的黄绵土表土和底土的团聚体进行培养,研究其对黄绵土的结构性、团聚体的孔隙特征以及不同粒径团聚体上有机质分布变化的效果及机理,主要结论如下:(1)4种胶结剂均可提高0.25 mm团聚体的含量,增加土壤团聚体的平均重量直径,且两者呈正相关关系,具有改善土壤结构,提高土壤功能的作用。PAM在浓度0.1%培养2周时,对全土和0.25 mm团聚体的平均重量直径等结构特征的改善效果达到显著水平,但培养时间对结构特征的改善作用不显著;对1~0.25 mm团聚体结构特征的改善效果明显,但对2~1 mm团聚体结构特征的改善在浓度0.2%以上或培养1个月以上效果才显著,培养时间对2~1 mm、1~0.25 mm团聚体的结构特征的改善作用明显。腐殖酸对2~1 mm团聚体结构特征的改善效果,短时间下须在浓度0.4%以上才可达到显著水平,但长期培养时浓度0.1%下即可达到显著的改良效果,改良效果随时间变化不明显;而对全土、1~0.25 mm和0.25 mm团聚体的结构特征的改善中,效果随着培养时间的延长呈显著变化,对1~0.25 mm团聚体而言,浓度0.2%培养2个月以上才能有显著效果。壳聚糖对全土表土的结构特征的改善效果随浓度梯度变化,随培养时间的延长改良效果差异明显。对2~1 mm和1~0.25 mm团聚体而言,结构特征的改善随时间变化显著,0.1%浓度下培养2个月有明显效果,0.2%浓度下只需培养1个月;0.25 mm团聚体的结构特征改善在浓度0.1%培养2周时就达到显著水平。硫酸铝对全土、2~1 mm和1~0.25 mm团聚体的结构特征的改善效果随着时间延长变化明显,对2~1 mm和1~0.25 mm团聚体结构特征的改善,需要培养2个月才能有效果;对0.25 mm团聚体结构特征的改善效果不明显。综上所述,在供试浓度(0.1%~0.4%)条件下,不同胶结剂对土壤团聚体结构特征的作用效果表现为PAM腐殖酸壳聚糖硫酸铝;0.25 mm团聚体施用胶结剂后效果最好,其次是全土,2~1 mm和1~0.25 mm团聚体效果比较差。这是因为这两个粒径的团聚体在培养过程中,小粒径的团聚体在有机质等的作用下互相黏结在一起,形成大团聚体,而大粒径的团聚体也有破碎为小团粒的部分,两者互相作用,总体变化不明显。(2)施用4种胶结剂后,表土各粒径团聚体上有机质的含量均显著高于底层土壤,胶结剂对底土中有机质含量的增加效果更明显,见效更快。施用PAM后,5~2 mm团聚体上的有机质含量随培养时间增加而增加,浓度0.1%培养2周与对照相比即达到显著水平;2~1 mm团聚体培养2周有机质含量的差异在浓度0.2%时才达到显著水平,浓度0.1%培养2个月差异显著;0.25 mm团聚体上的有机质含量在浓度0.2%培养4个月后与对照相比差异显著,达到极值。施用腐殖酸后,5~2 mm团聚体上的有机质含量随培养时间的变化并不显著,浓度0.1%培养2周与对照相比有显著差异;2~1 mm团聚体培养2周时有机质含量的差异在浓度0.2%时才达到显著水平,浓度0.1%培养1个月差异显著;0.25 mm团聚体上的有机质含量在浓度0.1%培养2周与对照相比差异显著。施用壳聚糖后,5~2 mm团聚体上的有机质含量在不同培养时间下的差别并不大,浓度0.2%培养2周时与对照相比达到显著水平,0.1%浓度时培养1个月差异显著;2~1 mm团聚体培养2周有机质含量的差异在浓度0.4%才达到显著水平,浓度0.1%培养1个月差异显著;0.25 mm团聚体上的有机质含量的差异在浓度0.1%培养2周与对照相比即达到显著水平。由以上分析可知,4种胶结剂作用下的不同粒径团聚体上有机质的含量随胶结剂浓度的增大呈增加趋势,适宜的胶结剂浓度为0.2%~0.4%;适宜的培养时间为2个月;壳聚糖的综合效果最好,作用显著,其次为PAM,腐殖酸最差;5~2 mm和2~1 mm团聚体上的有机质含量明显高于0.25 mm团聚体。(3)4种胶结剂均可提高团聚体的总孔隙度,增加通气孔隙和狭长孔隙的孔隙度,具有改善土壤通透性能的作用。PAM对团聚体内部孔隙特征及团聚体的孔径分布有很大影响,腐殖酸和硫酸铝对团聚体孔隙特征及孔径分布的影响有限,壳聚糖降低了规则孔隙和毛管孔隙的孔隙度,效果显著。短时间培养时,PAM、腐殖酸、壳聚糖对团聚体孔隙均能起到良好的改善作用,硫酸铝培养1个月后才有效果。
[Abstract]:In this study, loessial soil samples from the Loess Plateau were cultured with PAM, humic acid, chitosan and aluminium sulfate as soil cements. The structure, pore characteristics and aggregates of loessial soil samples were studied. The main conclusions are as follows: (1) All the four cements can increase the content of 0.25 mm aggregates and the average weight diameter of soil aggregates, and there is a positive correlation between them, which can improve the soil structure and improve the soil function. The improvement of structure characteristics such as average weight and diameter reached a significant level, but the effect of culture time on structure characteristics was not significant; the improvement of structure characteristics of 1-0.25 mm aggregates was obvious, but the improvement of structure characteristics of 2-1 mm aggregates was only significant when the concentration was above 0.2% or the culture time was more than 1 month, and the culture time was 2-1 mm, 1 mm. Humic acid can improve the structural characteristics of 2-1 mm aggregates obviously, and the improvement effect of humic acid on the structural characteristics of 2-1 mm aggregates can only reach a significant level in a short time at the concentration of more than 0.4%, but it can reach a significant improvement effect at the concentration of 0.1% in long-term culture, and the improvement effect is not obvious with time; but for the whole soil, 1-0.25 mm and 0.25 mm. For 1-0.25 mm aggregates, 0.2% chitosan can be cultured for more than 2 months. The improvement effect of Chitosan on the structural characteristics of topsoil varies with the concentration gradient, and the improvement effect varies with the culture time. For the aggregates of 1-0.25 mm and 1-0.25 mm, the improvement of structural characteristics changed significantly with time. The effect was obvious at 0.1% concentration for 2 months, and only one month at 0.2% concentration. The improvement of structural characteristics of 0.25 mm aggregates reached a significant level at 0.1% concentration for 2 weeks. The effect of different cements on the structural characteristics of soil aggregates was not obvious. In summary, the effect of different cements on the structural characteristics of soil aggregates was shown at the concentration of 0.1% ~ 0.4%. PAM humic acid chitosan sulfate aluminum; 0.25 mm agglomerate after the application of cementing agent, the best effect, followed by the soil, 2-1 mm and 1-0.25 mm agglomerate effect is poor. This is because the two size of agglomerates in the culture process, small size of agglomerate under the action of organic matter and so on, together to form a large agglomerate, and large particles. The content of organic matter in surface soil aggregates was significantly higher than that in the bottom soil, and the effect of cementing agent on the content of organic matter in the bottom soil was more obvious and faster. The content of organic matter increased with the increase of incubation time, and reached a significant level after 2 weeks of 0.1% incubation compared with the control; the difference of organic matter content between 2-1 mm aggregates reached a significant level after 2 weeks of 0.2% incubation, and the difference was significant after 2 months of 0.1% incubation; the content of organic matter on 0.25 mm aggregates reached a significant level after 4 months of 0.2% incubation. The content of organic matter in 5-2 mm aggregates did not change significantly with the culture time, and there was a significant difference between the two groups at 0.1% concentration for 2 weeks. The difference of organic matter content in 2-1 mm aggregates reached a significant level only at 0.2% concentration for 2 weeks, but at 0.1% concentration for 1 month. The content of organic matter in 0.25 mm aggregates was significantly different from that of the control at 0.1% concentration for 2 weeks. The difference of organic matter content of 0.25 mm aggregates reached a significant level when the concentration was 0.4% for 2 weeks and 0.1% for 1 month. The difference of organic matter content of 0.25 mm aggregates reached a significant level when the concentration was 0.1% for 2 weeks compared with the control. The content of chitosan was the best, followed by PAM, and humic acid was the worst. The content of organic matter in 5-2 mm and 2-1 mm aggregates was significantly higher than that in 0.25 mm aggregates. The total porosity of aggregates, the porosity of aerated pores and narrow pores are increased, and the permeability of soil is improved. PAM has great influence on the pore characteristics and pore size distribution of aggregates. Humic acid and aluminum sulfate have limited influence on the pore characteristics and pore size distribution of aggregates. Chitosan reduces regular pores and capillaries. PAM, humic acid and chitosan can improve the porosity of aggregates in a short period of time, and aluminum sulfate can only improve the porosity of aggregates after one month.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S152

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