Choosing the right soil is paramount to producing a good crop. And each vegetable and fruit requires something a little different from you. For example, a potato requires very loose soil so that it had plenty of room for the roots to travel down and feed off of the nutrients around it and begin its growing process. By not having loose soil you are restricting the growth of the vegetables, which will result in a poor crop when you come to harvest your food.
Also making sure you have healthy soil, with balanced pH levels based on what you plan to grow is just as important. Some vegetables can grow in harsh soil while others are more delicate a require you to be pickier with your soil.