我们讨论的是对土壤的间接改良，但还有直接的作用。

What we have been discussing are the indirect improvements of soils. But there are direct results, too.

youdao

我们讨论的是对土壤的间接改良，但还有直接的作用。

What we have been discussing are the indirect improvements of soils. But there are direct results, too.

youdao