Root vegetables develop easily in deep, consistent and well-drained earth. To avoid the foliage developing too quickly to the detriment of the underground part, farmers need to make sure that the soil is not too nitrogen-rich. Certain root vegetables exhaust the soil. This is the case for turnips, kohlrabi or Jerusalem artichokes. Adding a fertiliser after growing them is recommended. In the same way, Allium crops (garlic, onion, shallot) develop a lot of toxins. This is why it is not recommended to grow them 2 years in a row in the same location.