甘磊 张俊 郑思文 韦本辉 李健 李帅 邓婉珍

摘要：【目的】探討秸秆覆盖对广西甘蔗地土壤孔隙结构、孔隙数量、连通性等性质的影响，分析土壤孔隙结构特点及水分运移通道特征，为广西地区甘蔗生产中的科学合理种植提供理论依据。【方法】设秸秆覆盖（SM）与无秸秆覆盖对照（CK）2种处理，利用CT扫描成像技术和ImageJ软件获取土壤孔隙结构数据并测定土壤有机质，结合原位监测获得的5、20、40 cm深度的土壤含水量数据，对比分析不同处理的孔隙结构特点及土壤水分运移通道特征。【结果】SM处理0～10 cm土层的有机质含量显著高于CK（P<0.05，下同）;相同深度下SM处理的土壤含水量均高于CK。0～40 cm土层中，SM处理的土壤孔隙面密度显著大于CK，而CK的土壤孔隙复杂度显著高于SM处理。SM处理的孔隙数量（19190个）、直径≥1 mm孔隙数量（952个）、孔隙度（0.07%）及比表面积（1.64 mm-1）均显著大于CK对应值（9415个，690个，0.06%，1.43 mm-1）。土壤孔隙三维结构显示，CK的总孔隙数量少且多分散在0～20 cm土层，空间分布呈明显的分层现象;而SM处理的总土壤孔隙数量多且均匀分布在整个空间，无明显孔隙分布分层现象，且其连通性孔隙发育较完善。【结论】秸秆覆盖处理可有效提高广西甘蔗地的土壤含水量，增加土壤孔隙数量，从而整体提高土壤孔隙连通性，对土壤孔隙结构改善有一定积极影响，有利于促进甘蔗根系的生长发育。

关键词： 秸秆覆盖;土壤孔隙;CT扫描;土壤水分;甘蔗

中图分类号： S152.7                                    文献标志码： A 文章编号：2095-1191（2021）07-1745-08

Effects of straw mulching on the change of soil moisture and structure in sugarcane field in Guangxi

GAN Lei1，2， ZHANG Jun3， ZHENG Si-wen2， WEI Ben-hui4*， LI Jian2，

LI Shuai3， DENG Wan-zhen2

（1Guilin University of Technology/Guangxi Collaborative Innovation Center for Water Pollution Control and Safety

in Karst Area，Guilin， Guangxi  541004， China; 2Guilin University of Technology/Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology， Guilin， Guangxi  541004， China; 3Guilin University of Technology/Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology for Science

and Education Combined with Science and Technology Innovation Base， Guilin， Guangxi  541004， China;

4Institute of Economic Crops，Guangxi Academy of Agricultural Sciences， Nanning  530007， China）

Abstract：【Objective】The effects of straw mulching on the properties of soil pore structure， pore quantity and connectivity of sugarcane field in Guangxi were investigated to analyze the characteristics of soil pore structure and water transport channel， which provided theoretical basis for scientificand rational planting of sugarcane in Guangxi. 【Method】Two treatments including straw mulching （SM） and no straw mulching（CK） were set up to obtain soil pore structure data by CT scanning imaging technology and ImageJ software. Meanwhile the soil organic matter and soil water content at 5， 20 and 40 cm depth in-situ were measured. These data were used to analyze the pore structure characteristics and soil water movement channels in different treatments. 【Result】The organic matter content of 0-10 cm soil layer in SM was significantly greater than that of CK（P<0.05， the same below）. The soil water content under SM treatment was significantly higher than that of CK at the same depth. In 0-40 cm soil layer， the soil pore surface density of SM was significantly greater than that of CK， while the soil pore complexity of CK was significantly higher than that of SM treatment. The quantity of pores （19190） and pores with diameter ≥1 mm（952）， porosity（0.07%） and specific surface area（1.64 mm-1） treated by SM were all significantly higher than those treated by CK（9415， 690， 0.06%， 1.43 mm-1）， respectively. The three-dimensional structure of soil pores showed that the relative few pores were mostly dispersed in the 0-20 cm soil layer within obvious stratification in spatial distribution in CK. However， However， the soil pore number treated with SM were large and evenly distributed throughout the space， the obvious stratification of pore distribution was not observed in SM. The relative more pores were distributed in the whole space which induced the well-developed connectivity. 【Conclusion】Straw mulching can effectively increase soil water content and quantity of soil pores，  results in the better soil pore connectivity， which can improve the soil structure， finally promote the development of root system for sugarcane.

Key words： straw mulching; soil pores; CT scan; soil moisture; sugarcane

Foundation item： National Natural Science Foundation of China（42067002，41761048）; Guangxi Natural Science Foundation（2016GXNSFAA380197， 2019GXNSFDA245013）

0 引言

【研究意义】蔗糖业是广西重要的经济产业，甘蔗作物的生长发育状况对该产业的发展有着重要影响。广西地处岩溶区，复杂而脆弱的岩溶环境及降雨时空分布不均的条件，导致该地区甘蔗种植生产受到干旱等灾害影响，农业用水短缺问题日益严峻。此外，近年不合理的种植及过度开垦也造成土壤质量不断退化（仝金辉等，2017）。土壤结构是农业土壤质量的重要体现，良好的土壤结构具有调节土壤水气平衡的作用（张维俊等，2019），土壤孔隙的几何结构、空间分布特性及连通程度均会对土壤的水分运移与保持产生重要影响（Li et al.，2017），而土壤水分与土壤结构对于作物种植有着重要影响。秸秆覆盖作为一种改善土壤性状、促进作物生长和维持土壤中水分含量稳定的有效措施（Zhang et al.，2015），已在多种作物种植中应用，研究发现，表层覆盖秸秆能明显抑制水分蒸发（张金珠等，2015），改善表层土壤团粒结构，增加保水能力（陈帅等，2016）。……