The conclusion is: It's a variation in space, not in time.

结论是：它是空间的变化，而非时间的。

youdao

However, there exists an amount of space on the study of soil surface variation.

而在土壤表层水盐变化规律这方面，仍存在研究空间。

youdao

However, there exists an amount of space on the study of soil surface variation.

而在土壤表层水盐变化规律这方面，仍存在研究空间。

youdao