Q.improving bad section
We have nice zoysia jamur in front and back. In the front, a full half section does not grow lush and green as the section next to it. There is a line that divides the low growing grass from the tall grass. It is on an incline and may be a bit more packed. Should I aerate the bad part? My backyard is fully lush. I am going to put a small garden in the grass (6 ft. diameter). Can I lift the existing sod, cut into small pieces and somehow plug sections of the bad growing section of the front? I imagine I might then have plugs stuck in still low growing grass. I could send a photo or would like to speak to someone. The front yard is so beautiful except for this one section that is immediately next to a good section. There is no physical divider. The good lush immediately changes to the no/slow growing section.
I would start with determining if you have a build up of thatch.
Here is a few links with more information.
It may be that you have a issue with Brown Patch.
https://www.gardeningknowhow.com/lawn-care/specific/zoysia/zoysia-diseases-tips-for-dealing-with-zoysia-grass-problems.htm
https://www.gardeningknowhow.com/lawn-care/specific/zoysia/facts-about-zoysia-grass-zoysia-grass-problems.htm