title: [Characteristics of soil water movement using stable isotopes in red soil hilly region of northwest Hunan].
abstract: Stable isotope techniques provide a new approach to study soil water movement. The process of water movement in soils under two kinds of plant types (oil tea and corn) were studied based on the observed values of hydrogen and oxygen isotopes of precipitation and soil water at different depths in red-soil sloping land. The results showed that stable isotopes of precipitation in this area had obvious seasonal effect and rainfall effect. The stable isotopes at 0-50 cm depth in oil tea forestland and at 0-40 cm depth in corn cropland increased with the increase in depth, respectively, but they had the opposite tendency after rainfall in arid time. The stable isotopes decreased with the increase in depth below 50 cm depth in oil tea forestland and below 40 cm depth in corn cropland where evaporation influence was weak. The infiltrate rate of soil in oil tea land was affected by precipitation obviously, and it was about 50-100 mm/d after 2-3 days in heavy rain, slowed sharply later, and soil water at 50 cm depth often became a barrier layer. The permeability of soil in corn land was poor and the infiltration rate was lower. The change of stable isotopes in soil water in red soil hilly region was mainly affected by the mixing water which was formed by the antecedent precipitation, and evaporation effect took the second place. The evaporation intensity in oil tea land was lower than that in corn land, but the evaporation depth was higher.
authors.affiliation: Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China. tianrichang1981@163.com
authors.forename: Ri-Chang
authors.initials: RC
authors.lastname: Tian
authors.forename: Hong-Song
authors.initials: HS
authors.lastname: Chen
authors.forename: Xian-Fang
authors.initials: XF
authors.lastname: Song
authors.forename: Ke-Lin
authors.initials: KL
authors.lastname: Wang
authors.forename: Qing-Qing
authors.initials: QQ
authors.lastname: Yang
authors.forename: Wei
authors.initials: W
authors.lastname: Meng
mesh_terms: D002681:China; D007553:Isotope Labeling; D011891:Rain; D012987:Soil / Q000032:analysis*; D013662:Tea / Q000254:growth & development; D014867:Water / Q000032:analysis; D014872:Water Movements; D003313:Zea mays / Q000235:genetics
chemical_list: D012987:Soil; D013662:Tea; D014867:Water