soil horizon meaning in English

土层位
土壤层位

Denitrification and nitrogen fixation in 10 cm 20 cm horizon are higher than those in other soil horizons , in which the partial pressure of oxygen is lower than that in surface horizon , and the number of microorganisms is more than that in below horizon
高寒草甸土壤中未发现有好气性自生固氮菌，但嫌气性自生固氮菌的数量众多。在高寒草甸严酷的自然条件下，嫌气性自生固氮菌为大气氮素固定的主要承担者。