b-horizon的翻译，读音

B 层 (B céng)

Explanation:

• B horizon is a term in soil science that refers to the layer below the topsoil (A horizon).
• B层 is the direct Chinese translation for "B horizon", where 层 (céng) means "layer".

Example usage:

• 土壤的 B 层通常富含粘土和铁氧化物。 (Tǔrǎng de B céng tóngcháng fùhán nián tǔ hé tiě yǎnghuàwù.)
• The B horizon of soil is usually rich in clay and iron oxides.