Chaff (; ) is dry, scale-like plant material such as the protective seed casings of

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

s, the scale-like 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 numbe ...

. Chaff cannot be digested by humans, but it may be fed to livestock,

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 soil, or burned.

Etymology

"Chaff" comes from

Middle English Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English ...

''chaf'', from Old English , related to

Old High German Old High German (OHG; german: Althochdeutsch (Ahd.)) is the earliest stage of the German language, conventionally covering the period from around 750 to 1050. There is no standardised or supra-regional form of German at this period, and Old High ...

''cheva'', "husk".

Grain chaff

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in law ...

es (including

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

such as

rice Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly '' Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and ''Porteresia'', both wild and domestica ...

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 ...

oats The oat (''Avena sativa''), sometimes called the common oat, is a species of cereal grain grown for its seed, which is known by the same name (usually in the plural, unlike other cereals and pseudocereals). While oats are suitable for human co ...

, and

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeolog ...

), the ripe seed is surrounded by thin, dry, scaly

bracts In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or o ...

(called

glumes 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 an ...

lemmas 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 ...

, 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 Einkorn wheat (from German ''Einkorn'', literally "single grain") can refer either to a wild species of wheat (''Triticum'') or to its domesticated form. The wild form is '' T. boeoticum'' (syn. ''T. m.'' ssp. ''boeoticum''), the domesticated ...

,Potts, D. T. (1996) ''Mesopotamia Civilization: The Material Foundations''

Cornell University Press The Cornell University Press is the university press of Cornell University; currently housed in Sage House, the former residence of Henry William Sage. It was first established in 1869, making it the first university publishing enterprise in ...

. p. 62. .

emmer Emmer wheat or hulled wheat is a type of awned wheat. Emmer is a tetraploid (4''n'' = 4''x'' = 28 chromosomes). The domesticated types are ''Triticum turgidum'' subsp. ''dicoccum'' and ''Triticum turgidum ''conv.'' durum''. The wild plant is ...

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. ...

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 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. History ...

" – traditionally done by milling or pounding. Separating remaining loose chaff from the grain is called "

winnowing Winnowing is a process by which chaff is separated from grain. It can also be used to remove pests from stored grain. Winnowing usually follows threshing in grain preparation. In its simplest form, it involves throwing the mixture into th ...

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

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 Bran, also known as miller's bran, is the hard outer layers of cereal grain. It consists of the combined aleurone and pericarp. Corn (maize) bran also includes the pedicel (tip cap). Along with germ, it is an integral part of whole grains ...

, which is a finer, scaly material that is part of the grain itself.

Straw chaff

Chaff is also made by chopping

(or sometimes coarse

hay Hay is grass, legumes, or other herbaceous plants that have been cut and dried to be stored for use as animal fodder, either for large grazing animals raised as livestock, such as cattle, horses, goats, and sheep, or for smaller domesticate ...

) 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, it is used as animal feed, and is a way of turning coarse fodder into a form more palatable to livestock.

Botany

botany Botany, also called plant science (or plant sciences), plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "bot ...

, chaff refers to the thin receptacular

of many species in the sunflower family

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae ...

and related families. They are modified scale-like leaves surrounding single

floret This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary ...

s in the flower-head.

Metaphor

Chaff as a waste product from grain processing leads to a

metaphor A metaphor is a figure of speech that, for rhetorical effect, directly refers to one thing by mentioning another. It may provide (or obscure) clarity or identify hidden similarities between two different ideas. Metaphors are often compared wit ...

ical use of the term, to refer to something seen as worthless. In the

Bible The Bible (from Koine Greek , , 'the books') is a collection of religious texts or scriptures that are held to be sacred in Christianity, Judaism, Samaritanism, and many other religions. The Bible is an anthologya compilation of texts o ...

, such use is found in Job 13:25, Isaiah 33:11, Psalm 83:13-15, and other places. Chaff also lends its name to a radar countermeasure, composed of small particles dropped from an aircraft.

Use

Hungarian engineer László Schremmer has discovered that the use of chaff-based filters can reduce the

arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, bu ...

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 An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials ( gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characteri ...

.Newspaper article
(in Hungarian) published by

Magyar Nemzet ''Magyar Nemzet'' ('' en, Hungarian Nation'') is a major Hungarian newspaper published in Hungary, and in 2021 styled itself as "close to the current Hungarian government led by Viktor Orbán." History and profile ''Magyar Nemzet'', a moderate ...

on April 15, 2012.

References

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