冻融循环和初始土壤含水量对东北黑土区土壤崩解速率的影响

发布时间：2020-09-25 17:26

　　黑龙江省是中国黑土的主要分布区。然而由于剧烈的农业活动以及水蚀、风蚀和冻融作用的影响,导致了该地区的黑土层厚度不断降低。土壤崩解速率是表征土壤团聚体稳定性的重要参数。过去几十年间,有关土壤崩解速率的研究主要集中在黄土高原,但缺乏冻融循环对土壤崩解速率的影响研究,特别是在中国东北黑土区冻融循环在春季融雪过程普遍发生,而有关缺乏冻融循环对黑土区土壤崩解速率的影响研究基本为一空白。为此,本研究通过采集中国黑龙江省典型薄层黑土区宾县(BX)和克山县厚层黑土区(KS)原状土和扰动土样品,设计5个水平冻融循环次数(0、1、3、5和7次)和3个水平前期土壤含水量(16.5%、24.8%和33%)和采用改进的土壤崩解速率测定方法,定量分析了冻融循环和前期土壤含水量对黑土区土壤崩解速率的影响,研究结果可加深对冻融作用影响坡面土壤侵蚀机理的认识。主要研究结论如下:(1)当初始土壤含水量从16.5%增加到24.8%时,土壤崩解速率减少3倍;且在初始土壤含水量为16.5%时,试验土样在6 min内完全崩解。与初始土壤含水量为16.5%的试验土样相比,初始土壤含水量为24.8%和33.0%的试验土样发生崩解的时间缩短5倍。(2)经历1次冻融循环后,KS土壤崩解速率增加3倍;当冻融循环次数从5次增加到7次时,其土壤崩解速率增加2倍。当冻融循环次数从0次增加到7次时,BX土壤崩解速率缓慢增加。同时,经历1次冻融循环后,KS土壤崩解时间减少64%和7次冻融循环后其土壤崩解时间减少95%。而BX土壤崩解时间随着冻融循环次数增加而逐渐增加。当冻融循环次数从3次增加到7次时,KS土壤崩解速率比BX土壤崩解速率增加5倍。当冻融循环次数从0次增加到7次时,KS土壤崩解时间比BX土壤崩解时间减少10倍。(3)当冻融循环次数从3次增加到7次时,KS重塑土与原状土的土壤崩解速率分别增加6和5倍;而BX重塑土与原状土的土壤崩解速率皆随着冻融循环次数增加缓慢增加。(4)BX和KS土壤崩解速率与冻融循环次数的相关系数分别为0.906和0.906,这表明土壤崩解速率与冻融循环次数呈显著正相关(P0.05);而BX和KS土壤崩解速率皆与初始土壤含水量负相关,相关系数分别为-0.764和-0.858。
【学位单位】：西北农林科技大学
【学位级别】：硕士
【学位年份】：2019
【中图分类】：S157.1
【文章目录】：
abstract
摘要
CHAPTER 1 INTRODUCTION
    1.1 Background and Research Importance
        1.1.1 Background
        1.1.2 Research importance
    1.2 Literature Review
        1.2.1 Effects of freeze-thaw cycles and Initial soil water content on soil mechanics
        1.2.2 Soil disintegration rate
        1.2.3 The measurement of soil disintegration rate
    1.3 Current existing scientific issues
CHAPTER 2 RESEARCH CONTENTS AND METHODS
    2.1 Research objectives
    2.2 Research Contents
        2.2.1 Initial soil water content impact on soil disintegration rate
        2.2.2 Effects of freeze-thaw cycles on soil disintegration rate
        2.2.3 Comparison of soil disintegration rate between remolded and undisturbed soils
        2.2.4 Correlation between soil disintegration rate and soil properties
    2.3 Technical routine
    2.4 Research methods
        2.4.1 Study site
        2.4.2 Experimental device
        2.4.3 Experimental Setup
    2.5 Data analysis
CHAPTER 3 INITIAL SOIL WATER CONTENT IMPACTS ON SOIL DISINTEGRATION RATE AND PROCESS
    3.1 Introduction
    3.2 Materials and Methods
    3.3 Results
        3.3.1 Initial soil water content influence on soil disintegration rate
        3.3.2 Initial soil water content influence on soil disintegration process
    3.4 Discussion
    3.5 Conclusion
CHAPTER 4 EFFECTS OF FREEZE-THAW CYCLES ON SOIL DISINTEGRATION RATE AND PROCESS
    4.1 Introduction
    4.2 Materials and Methods
    4.3 Results
        4.3.1 Freeze-thaw cycle influence on soil disintegration rate
        4.3.2 Freeze-thaw cycle influence on soil disintegration process
    4.4 Discussion
    4.5 Conclusion
CHAPTER 5 COMPARISON OF SOIL DISINTEGRATION RATE AND PROCEDURE BETWEEN REMOLDED SOIL AND UNDISTURBED SOIL
    5.1 Introduction
    5.2 Materials and Methods
    5.3 Results
        5.3.1 Comparison of soil disintegration rate between remolded soil and undisturbed soil
        5.3.2 Comparison of soil disintegration processes between remolded soil and undisturbed soil
    5.4 Conclusion
CHAPTER 6 CORRELATION BETWEEN AFFECTING FACTORS AND SOIL DISINTEGRATION RATE
    6.1 Introduction
    6.2 Results
    6.3 Conclusion
CHAPTER 7 CONCLUSIONS AND PERSPECTIVES
    7.1 The Main Conclusions
    7.2 Perspectives
REFERENCES
ACKNOWLEDGEMENTS
BIOGRAPHY

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