表土的腐殖质含量 humus content of topsoils
土地的表层 layer of soil
混凝土表面的浮浆层 laitancecoating
代表性土样的确定方法 method for representative soil sample determination
土表的铵态氮也呈波动变化，随着烤田时间的增加铵态氮含量降低。
The concentrate of ammonium-N fluctuated in soil surfaceand decrease as the delay of soil drying.
土表的硝态氮浓度不断增加，烤田增大了复水后硝态氮向地下水淋溶的趋势。
The concentration of nitrate-N increased continuously in soil surface, which resulted in nitrate leaching to groundwater after rewetting.
实验表明：净风对土表的风蚀作用微弱，即使在遭到大风吹刮时，土表的结壳仍不易受到破坏。
The experiment indicates that wind itself is of weak effect on ground surface erosion, so that the soil crust may not be destroyed even under great wind velocity.
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