Crop rotation is the systematic planting of different crops in a particular order over several years in the same growing space. This process helps maintain nutrients in the soil, reduce soil erosion, and prevents plant diseases and pests. When a single crop is grown in one field for many years in a row, the crop will cause the depletion of particular nutrients from the soil. This depletion of nutrients leads to poor plant health and lower crop yield. With crop rotation, particular nutrients are replenished depending on the crops that are planted. For example, a simple rotation between a heavy nitrogen using plant (e.g., corn) and a nitrogen depositing plant (e.g., soybeans) can help maintain a healthy balance of nutrients in the soil. Crop rotation also prevents plant diseases and pests by exchanging crops that may be susceptible to a particular disease or pest with a crop that is not susceptible. For example, although corn is affected by corn root worms, soybeans are not. The soybeans help suppress the pest so that the corn planted the following year will not be as adversely affected by it. Fields may also be used as animal pastures or allowed to lay fallow until the following year. For organic farms and gardens, crop rotation is essential as it helps limit the amount of fertilizers and pesticides normally required .