Rice straw is the dried leaves and stems of the rice plant that remains after the rice grain is removed. After rice crops have been harvested in the fall, this rice straw is used as a mulch in the agricultural field. Rice straw is lightweight, biodegradable, neutral in pH and rarely contains weed seeds. It can also be used as a base layer for another mulch. Rice straw mulching has a significant effect on conserving initial soil moisture and reducing weed growth. In the spring the rice straw is tilled into the soil to add nutrients for the new crop of rice plants. It is also used in vegetable gardens, and as a winter covering.