upper soil layer meaning in English

土壤表层

The estimate of fine root biomass in upper soil layer of larix olgensis plantation by geostatistics method
采用地统计学方法对落叶松人工纯林表层细根生物量的估计
3 . soil n2o discharge flux of mulch was higher than that of no mulch treatment , and with the depth of 5 , 10 , 20cm the soil n2o discharge flux and the net adding flux increased in the order of depth in the upper soil layers
3地膜覆盖使5 ， 10 ， 20cm土层处n _ 2o的排放通量较未覆膜处理显著增加，且随着土层的加深，排放量依次增大，增加幅度也表现为下层大于上层。
In the zinc deficient cumulic cinnamon soil of northern china often encountered by dry climate , although the storing water in lower soil depth could not promote early maize plant to take up more zn from soils , our research gave a clear point that soil water in upper soil layer was important to enhance the influence of zn application in topsoil on early maize growth
表层土壤水分对苗期玉米植株锌吸收总量有显著影响，干旱条件下，玉米植株锌吸收总量下降；底层土壤水分供应状况对玉米锌浓度影响不大，但植株中锌向地上部运转增加。