Straw bale construction uses baled straw from wheat, oats, barley, rye, rice and others in walls covered by stucco. Straw bale are traditionally a waste product which farmers do not till under the soil, but do sell as animal bedding or landscape supply due to their durable nature. In many areas of the country, it is also burned, causing severe air quality problems. It is important to recognize that straw is the dry plant material or stalk left in the field after a plant has matured, been harvested for seed, and is no longer alive. Hay bales are made from short species of livestock feed grass that is green/alive and are not suitable for this application. Hay is also typically twice the price of straw.