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
glumes,
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
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 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 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 finer scaly material that is part of the grain itself.
Straw chaff
Chaff is also made by chopping
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 ...
(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
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 bracts 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
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.
See also
* Awn (botany)
* Bran
*Biomass
Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...
*Combine harvester
The modern combine harvester, or simply combine, is a versatile machine designed to efficiently harvest a variety of grain crops. The name derives from its combining four separate harvesting operations—reaping, threshing, gathering, and winnow ...
* Rice hulls
* Rice huller
References
{{reflist
Plant morphology
Fodder
Waste
ca:Espícula#Glumel·les