Yes salad can make you poop.
The salad which contains lettuce has fiber in the lettuce and when you eat that lettuce that contains fiber your bowels can begin moving.
Lettuce in salads are healthy for you though but some people have issues digesting lettuce so they may also experience bloating, stomach pain and diarrhea.
But if you're just getting a bowel movement and needing to poop soon after you eat the salad then it's very normal to need to poop after eating salad.
All foods do make us poop eventually but some people need to poop sooner than other people after eating the salad or other certain foods.