引用本文:李胜龙,易 军,刘目兴,张 君,杨 燕,张海林.稻田—田埂过渡区土壤优先流特征研究[J].土壤学报,2018,55(5):1131-1142.
LI Shenglong,YI Jun,LIU Muxing,ZHANG Jun,YANG Yan,ZHANG Hailin.Characteristics of Preferential Flow in the Intermediate Zone between Paddy Field and Ridge[J].Acta Pedologica Sinica,2018,55(5):1131-1142
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稻田—田埂过渡区土壤优先流特征研究
李胜龙,易 军,刘目兴,张 君,杨 燕,张海林
地理过程分析与模拟湖北省重点实验室,华中师范大学城市与环境科学学院,地理过程分析与模拟湖北省重点实验室,华中师范大学城市与环境科学学院,地理过程分析与模拟湖北省重点实验室,华中师范大学城市与环境科学学院,地理过程分析与模拟湖北省重点实验室,华中师范大学城市与环境科学学院,地理过程分析与模拟湖北省重点实验室,华中师范大学城市与环境科学学院,地理过程分析与模拟湖北省重点实验室,华中师范大学城市与环境科学学院
摘要:
为揭示田埂对稻田—田埂过渡区土壤水分渗漏的影响,对比不同位点(田内、过渡带和田埂)优先流特征差异,采用室外亮蓝染色示踪方法,对江汉平原典型稻田—田埂过渡区进行研究。结果表明:过渡区土壤染色面积比(SAR)随深度的增加呈波动下降,其中0~20 cm土层SAR较高,占剖面总SAR的53.85%~88.55%。不同位点土壤SAR差异明显,0~20 cm土层平均SAR由大到小依次为田内、过渡带、田埂,20 cm以下各位点SAR均较低,但田埂平均SAR高于田内。各位点水平剖面染色结果与垂直染色结果能较好对应,且随着深度增加,土壤染色区域急剧减少。各位点染色路径数(SPN)与SAR显著相关,田埂中、下层土壤SPN均高于田内。染色路径宽度(SPW)结果显示,0~20 cm田内以10~80 mm和大于80 mm SPW为主,过渡带和田埂大于80 mm SPW较少,均以小于10 mm和10~80 mm为主。各位点SPW的差异反映在水流类型上,田内为非均质指流—高相互作用大孔隙流,过渡区和田埂以混合作用大孔隙流—高相互作用大孔隙流为主。水分渗漏路径结果显示,田内水分由过渡带和田埂的垂直和侧向渗漏较强,且田沟田埂侧向流较田间田埂明显。田埂是稻田水分快速流失的主要区域,加剧了稻田水肥流失和水环境污染风险。本研究可为稻田水分保持和制定合理施肥、灌溉等措施提供依据。
关键词:  优先流  染色示踪  染色面积比  染色路径宽度  侧向流  稻田—田埂过渡区
DOI:10.11766/trxb201712070530
分类号:
基金项目:国家自然科学基金项目(41601215)和中央高校基本科研业务费(CCNU16A05015, CCNU17TS0001)资助
Characteristics of Preferential Flow in the Intermediate Zone between Paddy Field and Ridge
LI Shenglong,YI Jun,LIU Muxing,ZHANG Jun,YANG Yan and ZHANG Hailin
Key Laboratory for Geographical Process Analysis & Simulation, Hubei Province, College of Urban and Environmental Sciences, Central China Normal University,Key Laboratory for Geographical Process Analysis & Simulation, Hubei Province, College of Urban and Environmental Sciences, Central China Normal University,Key Laboratory for Geographical Process Analysis & Simulation, Hubei Province, College of Urban and Environmental Sciences, Central China Normal University,Key Laboratory for Geographical Process Analysis & Simulation, Hubei Province, College of Urban and Environmental Sciences, Central China Normal University,Key Laboratory for Geographical Process Analysis & Simulation, Hubei Province, College of Urban and Environmental Sciences, Central China Normal University,Key Laboratory for Geographical Process Analysis & Simulation, Hubei Province, College of Urban and Environmental Sciences, Central China Normal University
Abstract:
【Objective】Studies available in the literature have shown that the ridges around the paddy fields are likely to lead to low water use efficiency and pollution of shallow groundwater. Preferential flow is a physical process of water and solutes moving along certain pathways, like pores and fissures in the soil, while bypassing the part of soil matrix and is ubiquitous in the paddy field under continuous flooding. Therefore, to study the status of preferential flow in paddy soil and its influencing factors may help quantify characteristics of water leakage in paddy fields and improve water and fertilizer utilization efficiency, and hence reduce the risk of pollution of shallow groundwater by agricultural chemicals in paddy regions. In order to elucidate effects of the ridges on soil water leakage in the intermediate zone between fields and ridges, comparison was made of different monitoring points in the field, transition zone and ridges for differences in characteristics of preferential flow.【Method】Field bright blue dye tracer experiments were conducted of the soils in the two typical intermediate zones (i.e., the intermediate between field and ridge and the intermediate between ridge and ditch ) of > 100 years old paddy field in the Jianghan Plain, Hubei Province.【Result】Results show that stained soil area ratio (SAR) fluctuated downwards with depth of the soil profile and a peak was observed in the 0~20 cm soil layer, accounting for 53.85%~88.55% of the total SAR of the soil profile; that the field was the highest in SAR in this soil layer, and followed by the transition zone, and the ridge; that although SAR was quite low in soil below 20 cm in depth at all the monitoring sites, the ridge was still 3.15 times as high as the field in mean SAR; that staining of the soil appeared quite consistent horizontally and vertically, that with increasing soil depth, the area of staining at horizontal levels gradually decreased from a plane to a dot. The ridge, impact in soil texture, was higher than the field in staining path number (SPN) that in the 0~29 cm soil layer. staining path width (SPW) varied in the range 10~80 mm and beyond, while in the soil layers down below, only a few paths <10 mm were observed; that the water flow in the field was mainly of the type of heterogeneous finger flow – highly-interacted macropore flow, while in the transition zone and ridge, it was mainly of the type of mixing macropore flow- highly-interacted macropore flow, for the SPW therein varied in the range of 10~80 mm and below. When water flowed from the field into the transition zone, it lost through seepage vertically and laterally, the two typical pathways, (i) via earthworm pores, root pores and fissures, which were more plentiful in the ridge, facilitating vertical and horizontal seepage of the water, while the plough pan in the field made it hard for the water to leach downwards, thus forcing the water to flow into the ridge and then percolate rapidly into deep soil layers; and (ii) further into ditches through the intermediate between ridge and ditch, of which the two were relatively different in elevation, so the water infiltrating into the ridge continued flowing vertically through the ridge and eventually into the ditch, besides percolating downwards.【Conclusion】Affected by the distribution of macropores in the field, transition zone and ridge, only a small amount of water in the field infiltrated through the plough pan and a large one lost through seeping laterally into the ridge and then percolating quickly and vertically into deep soil layers through macropores, thus leading to low water use efficiency and nitrogen pollution of water bodies. It is, therefore, essential to pay high attention to the influence of water flow in the ridges on leakage of soil moisture and solutes from paddy fields.
Key words:  Preferential flow  Dye tracer  Stained area ratio  Stained path width  Lateral water flow  Paddy field-ridge intermediate