Class Registration Dilemma

So I'm a double STEM major. Which is a lot of work. But I've also been taking Mandarin for the past year and a half. Which is also a lot of work.

I was originally planning on taking 4 total semesters of Mandarin (I'm currently in my 3rd)... but, my schedule for next semester is very packed, without much wiggle room in terms of the other 3 classes I'm taking. If I were to drop Mandarin, I could take a statistics class, which would be very useful, or I could take a class on soil, which if I'm being honest is one of my biggest passions and also one of the main reasons I'm an environmental science major (seriously, I LOVE soil).

My Mandarin class is extremely stressful for me, but at the same time it's very useful, and also I have friends who are native speakers who I would love to be able to speak with in their first language (and it would be nice to speak with their families as well). On the other hand, the professor I've had the whole time is going on leave next semester, and the transition to a different one would add even more stress. I'm not really sure what to do.