秸秆还田下土壤孔隙演化及其对溶质穿透特征的影响机理分析  

Soil Pore Evolution and Effect on Solute Transport with Straw Application

作　　者：段正宇 朱成立[1] 车子刚[2] 嵇洪波 王策[1] 陈晓安 DUAN Zhengyu;ZHU Chengli;CHE Zigang;JI Hongbo;WANG Ce;CHEN Xiaoan(College of Agricultural Science and Engineering,Hohai University,Nanjing 211100,China;Department of Radiology,Nanjing Tongren Hospital,School of Medicine,Southeast University,Nanjing 211102,China;Jiangxi Academy of Water Science and Engineering,Nanchang 330029,China)

机构地区：[1]河海大学农业科学与工程学院,南京211100 [2]东南大学医学院附属南京同仁医院医学影像科,南京211102 [3]江西省水利科学院,南昌330029

出　　处：《农业机械学报》2024年第4期312-326,共15页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家自然科学基金项目(52109053);国家科技奖后备培育项目(20212AEI91011);江西省重点研发计划项目(20203BBGL73226);江苏省研究生科研与实践创新计划项目(SJCX22_0191);江苏省自然科学基金项目(BK20200523);江西省水利科学院开放基金项目(2021SKTR03);中国博士后科学基金项目(2021M690874)。

摘　　要：为揭示秸秆粉碎还田后,不同腐解进程下土壤孔隙演化及其对水分和溶质穿透特征的影响机理,设置不同秸秆还田量(0、5、10、15 t/hm^(2))和还田时间(0、30、60 d)处理,采用CT断层扫描技术,视觉量化了土壤孔隙结构特征演变,并基于溶质穿透试验,分析了水分-溶质迁移优先流规律。结果表明,秸秆还田引起土壤孔隙/喉道特征变化,抑制水分-溶质迁移过程,田间持水率和土壤含水率上升,溶质穿透变慢,优先流现象减少,土壤水肥有效持留;随秸秆腐解至60 d,孔隙/喉道特征改变,优先流开始发育,但土壤水肥持留能力增强。秸秆还田5、10、15 t/hm^(2)初期,和CK组相比大孔隙体积占比分别减少7%、14%、50%,连通孔隙减少11%、39%、66%,表层含水率增加1%、3%、6%。腐解60 d后,和0 d相比大孔隙体积占比分别增加331%、200%、357%,连通孔隙增加33%、84%、195%,表层含水率增加6%、5%、5%,完全穿透试样所需溶质减少55%、76%、67%。基于Green-Ampt模型和指数衰减模型估算了不同秸秆初始投入量在不同腐解时间下的导水特征,发现饱和导水率在秸秆还田后减小,且随秸秆腐解增大。研究可为控制大孔隙流和无效灌溉提供依据,进一步为秸秆科学还田提供实践指导。The evolution of pore structure and the mechanism of its influence on both soil moisture and solute breakthrough during the straw decomposition process were experimentally investigated.Treatments with straw application rates of 0 t/hm^(2),5 t/hm^(2),10 t/hm^(2),and 15 t/hm^(2) and decomposition time points of 0 d,30 d,and 60 d were set up for the CT tomography and breakthrough experiment.CT tomography was employed to visually quantify the evolution of soil pore structure,and the breakthrough experiment was employed to analyze the evolution of moisture-solute transport preferential flow pattern.The results showed that at the early stage of straw decomposition,features of soil pore/throat pathways were modified,which inhibited the moisture-solute transport.Field capacity and soil moisture content were increased,solute breakthrough was slowed down,and the preferential flow pattern was restrained with straw incorporation.Soil moisture and fertilizer can be effectively retained,consequently.As straw was decomposed to 60 d,the pore/throat pathways were changed,and the preferential flow began to develop,but the soil moisture and fertilizer retention capacity were increased.At the initial stage of straw application of 5 t/hm^(2),10 t/hm^(2),and 15 t/hm^(2),compared with the CK group,the proportion of macropore volume was decreased by 7%,14%,and 50%,the connected pore was decreased by 11%,39%,and 66%,the surface moisture content was increased by 1%,3%,and 6%.After 60 d of decomposition,compared with group 0 d,the proportion of macropore volume was increased by 331%,200%,and 357%,the connected pores was increased by 33%,84%,and 195%,the surface moisture content was increased by 6%,5%,and 5%,and the solute collected was decreased by 55%,76%,and 67% when completed breakthrough,respectively.Based on the Green-Ampt model and the exponential decay model,models for the estimation of saturated hydraulic conductivity were proposed with different straw application rates at different decomposition time points.It indicated that the s

关 键 词：秸秆腐解 孔隙结构 三维特征 大孔隙优先流 计算机断层扫描 穿透曲线 

分 类 号：S271[农业科学—农业水土工程] S278[农业科学—农业工程]