土壤耕作层 meaning in English

plough horizon

( 2 ) after a rainfall , the soil moisture in the plot iii was the highest , it was 21 . 33 % , and that of in the plot ii was the lowest ; meanwhile the conservation ability of the soil in the plot iii was the highest , that of in the plot ii was the lowest
第1 、 2小区产生的泥沙量也大于其余两个小区。 ( 2 )在一次降雨后的湿润条件下，第3区的土壤耕作层含水量最高，为21 . 33 ；第4区次之，第2区最低。