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Chaff (tʃæf; UKtʃɑːf) is the dry, scaly protective casing of the seeds of cereal grains or similar fine, dry, scaly plant material (such as scaly parts of flowers or finely chopped straw). Chaff is indigestible by humans, but some livestock can eat it. In agriculture, it is used as livestock fodder, or is a waste material ploughed into the soil or burned. "Chaff" comes from Middle English chaf, from Old English ceaf, related to Old High German cheva, "husk". In grasses (including cereals such as rice, barley, oats, and wheat), the ripe seed is surrounded by thin, dry, scaly bracts (called glumes, lemmas, and paleas), forming a dry husk (or hull) around the grain. Once it is removed, it is often referred to as chaff. In wild cereals and in the primitive domesticated einkorn, emmer and spelt wheats, the husks enclose each seed tightly. Before the grain can be used, the husks must be removed. The process of loosening the chaff from the grain so as to remove it is called "threshing" – traditionally done by milling or pounding. Separating remaining loose chaff from the grain is called "winnowing" – traditionally done by repeatedly tossing the grain up into a light wind, which gradually blows the lighter chaff away. This method typically uses a broad, plate-shaped basket or similar receptacle to hold and collect the winnowed grain as it falls back down. Domesticated grains such as durum and common wheat have been bred to have chaff that is easily removed. These varieties are known as "free-threshing" or "naked". Chaff should not be confused with bran, which is a finer, scaly material that is part of the grain itself. Chaff is also made by chopping straw (or sometimes coarse hay) into very short lengths, using a machine called a chaff cutter. Like grain chaff, it is used as animal feed, and is a way of turning coarse fodder into a form more palatable to livestock. In botany, chaff refers to the thin receptacular bracts of many species in the sunflower family Asteraceae and related families.

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Related concepts (15)

Threshing

Threshing, or thrashing, is the process of loosening the edible part of grain (or other crop) from the straw to which it is attached. It is the step in grain preparation after reaping. Threshing does not remove the bran from the grain. Through much of the history of agriculture, threshing was time-consuming and usually laborious, with a bushel of wheat taking about an hour. In the late 18th century, before threshing was mechanized, about one-quarter of agricultural labor was devoted to it.

Barley

Barley (Hordeum vulgare), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley production is used as animal fodder, while 30% as a source of fermentable material for beer and certain distilled beverages, and as a component of various foods. It is used in soups and stews, and in barley bread of various cultures.

Chaff