Chaff (; ) 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 Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number ...

). Chaff is indigestible by humans, but livestock can eat it. In agriculture it is used as livestock

fodder Fodder (), also called provender (), is any agriculture, agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, domestic rabbit, rabbits, sheep, horses, chickens and pigs. "Fodder" refers particularly to food g ...

, or is a waste material

plough A plough or plow ( US; both ) is a farm tool for loosening or turning the soil before sowing seed or planting. Ploughs were traditionally drawn by oxen and horses, but in modern farms are drawn by tractors. A plough may have a wooden, iron or ...

ed into the soil or burned.

Etymology

"Chaff" comes from Middle English ''chaf'', from

Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlement of Britain, Anglo ...

, related to Old High German ''cheva'', "husk".

Grain chaff

In grasses (including

cereal A cereal is any Poaceae, grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, Cereal germ, germ, and bran. Cereal Grain, grain crops are grown in greater quantit ...

s such as rice, barley, oats, and wheat), the ripe seed is surrounded by thin, dry, scaly bracts (called

glume In botany, a glume is a bract (leaf-like structure) below a spikelet in the inflorescence (flower cluster) of grasses (Poaceae) or the flowers of sedges (Cyperaceae). There are two other types of bracts in the spikelets of grasses: the lemma and ...

lemma Lemma may refer to: Language and linguistics * Lemma (morphology), the canonical, dictionary or citation form of a word * Lemma (psycholinguistics), a mental abstraction of a word about to be uttered Science and mathematics * Lemma (botany), a ...

s and paleas), forming a dry

husk Husk (or hull) in botany is the outer shell or coating of a seed. In the United States, the term husk often refers to the leafy outer covering of an ear of maize (corn) as it grows on the plant. Literally, a husk or hull includes the protective ...

(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,Potts, D. T. (1996) ''Mesopotamia Civilization: The Material Foundations'' Cornell University Press. p. 62. . emmer and

spelt Spelt (''Triticum spelta''), also known as dinkel wheat or hulled wheat, is a species of wheat that has been cultivated since approximately 5000 BC. Spelt was an important staple food in parts of Europe from the Bronze Age to medieval times. No ...

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 utilizes 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 wheat Durum wheat (), also called pasta wheat or macaroni wheat (''Triticum durum'' or ''Triticum turgidum'' subsp. ''durum''), is a Polyploid, tetraploid species of wheat. It is the second most cultivated species of wheat after common wheat, although ...

and

common wheat Common wheat (''Triticum aestivum''), also known as bread wheat, is a cultivated wheat species. About 95% of wheat produced worldwide is common wheat; it is the most widely grown of all crops and the cereal with the highest monetary yield. Ta ...

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 finer scaly material that is part of the grain itself.

Straw chaff

Chaff is also made by chopping

(or sometimes coarse hay) into very short lengths, using a machine called a

chaff cutter A chaff cutter is a mechanical device for cutting straw or hay into small pieces before being mixed together with other forage and fed to horses and cattle. This aids the animal's digestion and prevents animals from rejecting any part of their ...

. Like grain chaff this is used as animal feed, and is a way of turning coarse fodder into a form more palatable to livestock.

Botany

In botany, chaff refers to the thin receptacular bracts of many species in the sunflower family Asteraceae and related families. They are modified scale-like

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

surrounding single florets in the flower-head.

Metaphor

Chaff as a waste product from grain processing leads to a metaphorical use of the term, to refer to something seen as worthless. Like in Job 15:25, Isaiah 33:11, Psalm 83:13-15, among other things.

Use

Hungarian engineer László Schremmer has discovered that by the use of chaff-based filters it is possible to reduce the arsenic content of water to 3 microgram/litre. This is especially important in areas where the potable water is provided by filtering the water extracted from an underground aquifer.Newspaper article
(in Hungarian) published by Magyar Nemzet on April 15, 2012.

References

{{reflist Plant morphology Fodder Waste ca:Espícula#Glumel·les