Chaff Word Study

Chaff Subject Study

What Is Chaff.

The Threshing Process in Brief: How They Get Chaff.

My Misconceptions About Chaff.

Summary of “Crop Residue” Article and Chaff Density Calculations.

The Human Aspect of Relating to Chaff.

For Further Study:



Why A Study on Chaff?

Chaff can be quite interesting as the threshing process was an important part of life in biblical times. Just “a failure to appreciate the effects of crop-processing can lead to major misinterpretations”[1] for the archaeologist. Our lack of knowledge can lead to incorrect conclusions or an under appreciation of the text. Yet, Chaff seems so nominal to many people that they barely mention chaff. They tend to leap into the metaphorical uses of chaff without first building a foundational understanding of the role chaff played in the lives of ancient people. Bible encyclopedias and commentaries leave us thinking we know everything we need to know about chaff even though they have given chaff but a cursory touch. A person must understand the metaphors if they want to understand the Bible. Understanding the agriculture behind agricultural metaphors is essential to interpreting them and fully appreciating them.

Chaff was an important part of life in the ancient world. Everyone knew what it was. They had seen it flying in the wind. They had played in it as children. A study of chaff helps us to understand the life of the ancient people better. It can help us understand why the metaphorical use of chaff was so effective. The better understanding of chaff in the life of the ancient world brings out the vividness of the metaphorical use of chaff they had in their day into our world today to allow us to fully appreciate the metaphors.

Chaff Word Study

NASB[2] uses chaff 17 times while NET[3] uses it 18 times.

Two of these occurrences are in the New Testament.

The Old Testament Words (Hebrew)

NASB95 renders 4 different Hebrew words as chaff.

  • qash קַשׁ is translated as chaff (5), straw (1), but most often stubble (10 of 16)
    • Stubble: Exodus 5:12; Job 41:28, 41:29; Isaiah 5:24, 33:11, 40:24, 47:14; Joel 2:5; Obadiah 18; Nahum 1:10
    • Straw Jeremiah 13:24
    • Chaff: Exodus 15:7; Job 13:25; Psalm 83:13; Isaiah 41:2; Malachi 4:1
  • mots מֹּץ (8 of 8) is always translated as chaff.
  • Chaff: Job 21:18; Psalm 1:4, 35:5; Isaiah 17:13, 29:5, 41:15; Hosea 13:3; Zephaniah 2:2
    • hashash חֲשַׁשׁ is translated once as chaff and once as grass.
    • Chaff: Isaiah 33:11
    • Grass: Isaiah 5:24
  • ur עוּר only occurs once and is translated as chaff.
    • Chaff: Daniel 2:35

The lexiconical entry in HALOT[4] for מֹץ gives the Arabic word mauṣ with the Arabic word meaning of “straw.”  It continues with “chaff” and a supporting references.[5]  TDOT [6] says,

It occurs 8 times in the OT, always metaphorically in poetical texts. The LXX usually translates it with chnoús, although occasionally with ánthos and koniortós (dust).

TDOT gives thirty-one words to discuss threshing, but nothing about chaff or what part of the plant it is before diving into the metaphorical use of chaff in the Old Testament. There is little else to do but a word search for the above Hebrew words and examine the verses where the words appear. I encourage the reader to examine the verses provided above to understand their meanings farther.

The lexicons cover chaff as used in scripture, as do Bible encyclopedias.
Though I expected more from the encyclopedias about the stuff of chaff: what it is, its properties, how it acts in various conditions, how the people think of chaff and interact with it in their life activities. These are the kinds of questions that often lead to surprising insights into scripture and are well worth the added effort.

Chaff Subject Study

What Is Chaff:

If a person asks themselves, “What exactly is chaff?” They might find themselves reading specialized papers using large technical terms that are difficult to sort out to find the answer. This is further complicated when the modern miller considers chaff as one part of the plant while the agriculturist considers it another part of the plant. Wikipedia offers this relatively simple modern explanation.

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 removed, it is often referred to as chaff. [7]

Unfortunately, this is the wrong approach for this study because the people of the Bible were not looking at their wheat and barley through microscopes as we do today. For them straw was the stalk of the plant. The chaff was any of the rest of the plant that blew further[8] than the grain and straw during the winnowing of the grain.

Chaff could include small bits of straw, or possibly lots of straw, but most likely was composed of the loose leaves and head parts of the plant other than the grain itself that blew the furthest in the wind when winnowed. With this understanding of chaff, it is no longer a single small part of the plant we are examining. Instead, it is all the various head parts and perhaps some loose leaves and possibly small pieces of chopped straw.

We have lost much of our ability to learn about ancient threshing and winnowing because archaeologists were not interested in threshing floors, sledges, or other tools of the threshing process since threshing was still done much the same way in their own day. More recently, farmers were still using threshing practices similar to those of ancient times but quickly modernized when threshing machines emerged on the farming scene in the 1950’s. Almost everyone who knew the old way of threshing have already passed away. Their knowledge and stories of threshing the old way are largely lost to us now.

Ethnobotanist John C. Whittaker, whose primary research interests are in early technology, especially stone tools, talked with a sixty-six-year-old flintknapper in 1995. He was able to share what he learned about threshing sledges with flintstone threshing blades in the bottom of the threshing sled that cut the straw into small segments.[9] These cutting blades would explain why the Hebrew language has a word like קַשׁ (qash) that is translated as “chaff,” “stubble,” and “straw.” For today’s farmers, stubble is the part of the stalks that remain attached to the ground after they cut the stalks. This meaning of stubble is appropriate for some instances of the word קַשׁ (qash): such as when the Israelites had to use it for straw to make bricks when Pharaoh refused to provide straw for them (Ex 5:12). A careful reading of the context of the text often dictates if it is stubble, straw, chaff, or both straw and chaff. We may not always know the intended meaning with confidence. Sometimes the Bible leaves an ambiguity when we do not need to know for sure or God wants to allow several possible understandings.

The Threshing Process in Brief: How They Get Chaff [10]

Many people come together and help each other thresh and winnow their grain. This could include extended family, neighbors and hired labor as well as children doing what they can. The harvesting was an intense race in the hot sun to finish before the rains come. Keeping the grain dry was vital to their survival because mildew ruined the grain. The children worked, played, or slept nearby.

  1. They harvested wheat and barley with a cycle.
  2. The cut crop is bound into sheaves and carried to the threshing floor.
  3. They placed the sheaves on the threshing floor. They probably untied the sheaves and spread it out on the threshing floor.
  4. Thresh the grain.
    • Threshing methods:
      • Beat small bunches with a stick to knock the grain from the head of the stalk.
      • Drag a threshing sledge over it to rub the grain free of the head of the stalk and cut the straw into short pieces.
      • Roll a wheel-thresher over it to press and rub the grain free of the head of the stalk.
  5. Winnowing
    • Once the wind picked up in the evening, they would toss the threshed material into the air with a winnowing fork. The winnowing fork is a fork like shovel used for winnowing grain.[11] The material would float in the wind according to weight/volume-density as it fell. The material with the highest wind resistance to weight ratio would travel the farthest in the wind. The grain fell on the threshing floor while straw fell downwind, and chaff fell farther downwind.
  6. They sifted the grain through two types of sieves, kĕbārâ and nāpâ to separate it. They separated out the chaff and straw by winnowing before sifting the grain to avoid clogging the sieves.
  7. They placed clean grain in clay jars, pits, or storage houses.
  8. There were also uses for straw and chaff.
    • Farmers can feed straw and chaff to mature cattle as roughage but not as a complete diet.[12]
    • One could burn chaff as fuel to heat water in ancient times. [13]
    • Ancient people used chaff as an insulator to protect imported snow from the summer heat.[14] The snow was placed in a deep pit and covered with chaff so they could have chilled water during the hot season. Proverbs 25:13 may relate to such snow in summer.
My Misconceptions About Chaff
  1. FALSE: Surely it would take much grain threshing to produce enough chaff to gather and burn.
  • The chaff piles are much larger than the grain piles. We will learn this when calculating the density of chaff.
  • The barley chaff pile was 2 - 4 times the size of the grain pile.
  • The wheat chaff pile was 8-10 times the size of the grain pile.
  1. FALSE: I would think it would burn hot and fast since it is so light and seemingly airy.
  • A youtube video[15] shows a large pile of chaff burning very slowly.
  • Another youtube video[16] on burning chaff dumps.
  • A chaff dump (a modern wagon load of chaff) can take 10 hours to burn.
  • The people of ancient times burned chaff to warm water for baths.[17]
  • However, chaff can burn very rapidly when it is in the form of dust, but it is not in this state outside. But only in modern mills.
  • Today’s agricultural industry must take care to avoid explosions in modern grain mills. They must control the air to minimize the amount of dust in the air.
  • Chaff burns faster when it can get enough oxygen to its surface areas the same way saw dust does when sprinkled into a fire.
  1. FALSE: There is but a small amount of chaff separated from the grain during threshing.
  • As this study will show below, the chaff is about half the weight but many times the volume of the grain harvested.
Summary of “Crop Residue”[18] Article and Chaff Density Calculations.

This data is from crops grown with modern farming methods in rich soils. The chaff production is independent of soil richness although straw production increases with soil quality. This is true across wheat, barley, oats, canola, and peas. [19]

One should note that modern farmers harvest only the tops parts of grass crops using a combine to catch minimal straw without missing the heads of the crop to minimize the crop-residue. The standing straw is harvested later by mowing with a cycle mower and bailing for easy transporting where it is used as fodder and bedding for livestock.

Parts of Crop Produced for A Bushel of Grain.

  Grain (lbs.)
1 bushel
Straw (lbs.)Chaff (lbs.)Bushels of straw & chaff
1 Bushel





1 Bushel





The volume of straw produced is 3-4 times that of chaff. The density of wheat straw is 29 kg/m3 and 47 kg/m3 for barley straw.[20]

  • For every bushel (48 U.S. pounds) of grain, you get 60-45 U.S. pounds (15-17 bushels) of straw and chaff.

Chaff is 10-20% the weight of the harvest. Straw and chaff (crop residue) of barley is 15-17 times the size of the grain harvest.

  • For every bushel (60 lbs.) of grain, you get 45 lbs. of straw and 20-25 U.S. pounds of chaff. This is 33-35 bushels of straw and chaff together.
  • Chaff is 33-42% the weight of the harvest.
  • The crop residue pile(s) are much larger than the grain piles.
  • The wheat crop residue is 33-35 times the size of the grain harvest.

Modern farming uses chaff as:

  • A fertilizer that provides a very slow release of minerals,
  • A soil conditioner to hold moisture content in the soil.
    • A Livestock food-mix ingredient to add economical roughage.

There are still several things that could affect the kernel size and the chaff ratios. The kernels may have been smaller than modern wheat if their soil was not prepared or cultivated as well as in modern times. “Wheat varieties introduced since 1950” have contributed to increased chaff production.[21] Modern kernels are likely larger because of engineering the plants. Either way, these calculations would be the minimum ratios for Chaff. 1:3 for Barley and 1:10 for Wheat. The piles of straw are as large as the pile of chaff piles. That is 2.5 to 5 times for barley and 2.9 to 3.6 for wheat. The economic value of chaff depends on how one would use it.

Calculating the Density of Straw and Chaff for the Data Presented Above.

One issue to consider with this density calculation is “what is called chaff” in the context of the modern combine harvester is different that the chaff we have been discussing. The “Chaff” or “crop residue” exiting the combine includes all plant parts that are not grain. It includes chaff, some straw, leaves, and non-grain head parts. It is the average density of all plant residue. I have not found the required information to determine the density of chaff alone for this caluclation. This calculation determines the density of chaff with some straw and other plant parts mixed together, all of which would fly in the wind during the ancient winnowing process. This mixture is called “crop residue” in this article to avoid confusion with the term “chaff.”

Bushel weights from:



  • “If the wagon is filled, the piles are approximately four to five feet high, seven feet wide and 10 to 12 feet long, and weighs about 800 lb.”[22]
  • 5’ x 7’ x 11’ wagon load of residue = 385 cubic feet (665280 cubic inches) of chaff weighs 800 pounds
  • American bushel = 2150.42 cubic inches[23]
  • 1 wagon load = 665280/2150.42 = 309 bushels.
  • 800 pounds /309 bushels= 2.59 pounds per bushel
The Human Aspect of Relating to Chaff

Harvest time was arduous work in the heat of the day. The magnitude of the task found neighbor helping neighbor. The whole clan would turn out to get the job done before the rains came and ruined the crops. Threshing and winnowing was intense work. However, people threshed their grain in the cool of the evening once the breeze picked up. “A good breeze was crucial for winnowing.”[24]

Our limited knowledge of how people used chaff in Biblical times restricts what one may say about its uses; However, the volume of chaff produced makes it an important and dramatic part of the winnowing process. Chaff sometimes served as fuel for a fire. Perhaps, chaff also served as supplemental feed for the livestock. The chaff, possibly illuminated by fire light at night, would create a cloud from the threshing floor to the chaff pile. The chaff pile would grow sizable unless hauled away to storage as the winnowing continued.

Whittaker[25] also tells stories of children during threshing time. “Schools dismissed classes early in the afternoon so the children could help with the harvest, and they would run to ride on the dhoukanes [threshing sledge] and “accidentally” tumble off into the soft chaff.”[26] One lady told Whittaker, “I rode the voukani [threshing sledge] all day. Around and around and around went the voukani, and around and around went my head! I used to pray to God,” she gestured dramatically, “ ‘Please let me off this voukani, don’t make me do this all my life.”[27]

“Children would ride donkeys loaded with chaff back and forth from … the storage”[28]  It is hard to imagine the children being able to resist putting themselves in the path of wind-blown chaff even if the straw pelts them a bit any more than today’s children in the deserts resisting the temptation to run into whirlwinds, as dirt filled as it might be. Good or bad, these are the memories that make childhood an experience to remember. Bringing images of threshing to mind recalls these associated memories and ties the message to those earlier memories making the metaphor more relevant as well as making the message they heard much more vivid.

For Further Study:

If one knew the size of field people used as well as the likely crop yield compared to modern times, one could calculate the amount of chaff a person might have after the threshing and winnowing. I have found no evidence that the fields of Israel had set sizes for fields. However other cultures did. See wiki: Ancient Mesopotamian units of measurement but there seems to me some discrepancy exists.


The biggest discovery of this study is that there is so much chaff by volume compared to the grain. It is possible the Bible’s chaff included all crop residue as there is no distinction between the various parts of the plant when winnowing. Compared to the grain pile, the crop residue pile is up to 17 times the size for barley and up to 35 times the size for wheat. It is not by chance Jesus used wheat instead of the more common barley since wheat produces much more straw and chaff than barley does. This gives us a dependable idea of just how much material blew across in the wind as they winnowed the grain.

It is the vast volume of material blowing in the wind during the winnowing process that makes for a particularly good metaphor for separating the worthless from the valuable. The small basket of grain compared to the nearby much larger pile of chaff also illustrates Jesus’ saying, “the gate is wide … to destruction … “ Mt 7:13-14  It is this vast volume that is missed when discussing the metaphor separating the wheat from the chaff. This voluminous cloud of chaff illustrates the worthless “many” separated out from the relative few who serve God.

Though this information comes from areas near Israel, yet outside of it, it well known that technology spread from one area to another. They likely adopted it if there was benefit in it such as making it easier for livestock to eat the straw and chaff, easier to store, or to winnow. We see evidence of Israelite knowledge of this technology in Isaiah 41:15 .

“Behold, I have made you a new,
sharp threshing sledge with double edges;
You will thresh the mountains and pulverize them,
And will make the hills like chaff.
Isaiah 41:15 NASB95

The presence of flintstone blades would indicate the straw was shorter pieces rather than long pieces. Based on an estimate from a photograph,[29] the dhoukani referred to earlier had about 350 flintstone threshing blades attached to its bottom. This number of blades would cut the straw into very short lengths.

Another interesting discovery is the human side. Though the work was long and hard the people would enjoy seeing those they did not see often. We also learned of children working and playing during the harvest processes. This reveals that memories are associated with chaff that personalizes its metaphoric use.

Without a study like this we miss how dramatic winnowing can be by not realizing the sheer volume of material that separated from the grain and how little grain there is in comparison. There can be up to combined 50 bushels of straw up to 10 bushels of chaff for each bushel of wheat grain harvested. We can now think of short stalk lengths of straw due to the flintstone blades attached to the bottom of the threshing sledge. We can also think of the fellowship the workers have as they thresh the grain as well as the memories children form during these events in their lives that makes separating chaff such a good metaphor for separating the valued righteous from the worthless wicked in a way that is not only relevant to them because of the intimate knowledge and interaction with chaff but it is also close to their hearts because of the childhood memories formed with their family and friends which allows vivid recall and association of these memories with the metaphors upon hearing them.


The application comes in trying to get people to visualize the cloud of straw and chaff blowing in the wind by fire light with family and friends working nearby and relating this image to similar settings when memories in their own lives were formed. One can use personal experiences or scenes from popular moves, perhaps a barn raising scene[30], a ball game, sledding with friends down the neighborhood hill, a church camp, or a festive wedding. Draw parallels between their own memories and the memories the people of the Bible may have had relating to winnowing. Then relate the many particles in the cloud separated away from the righteous who serve the Lord as well as from God Himself, becoming separated forever from his presence. One could also involve threshing as the preparation for the winnowing process and separation of the chaff from the Wheat.


[1] Nesbitt, M. (2001). Plants and People in Ancient Anatolia. Biblical Archaeologist: Volume 58 1-4, (electronic ed.), 71.

[2] New American Standard Bible: 1995 update. (1995). La Habra, CA: The Lockman Foundation.

[3] Biblical Studies Press. (2005). The NET Bible First Edition; Bible. English. NET Bible.; The NET Bible. Biblical Studies Press.

[4] Koehler, L., Baumgartner, W., Richardson, M. E. J., & Stamm, J. J. (1994–2000). The Hebrew and Aramaic lexicon of the Old Testament (electronic ed., p. 619). Leiden: E.J. Brill.

[5] Ibid.

[6] Ringgren, H. (1997). מַעֲלָל, מַעֲשֶׂה and מֹץ. G. J. Botterweck & H.-J. Fabry (Eds.), D. W. Stott (Trans.), Theological Dictionary of the Old Testament (Revised Edition, Vol. 8, p. 464). Grand Rapids, MI; Cambridge, U.K.: William B. Eerdmans Publishing Company.


[8] It is an assumption that the chaff blew further than the straw. It is possible there was only one pile of crop residue or likely that the two piles blended into an oblong elliptical shaped pile.

[9] Whittaker, J. C. (2000). Alonia and Dhoukanes: The Ethnoarchaeology of Threshing in Cyprus. Near Eastern Archaeology, 63(1–4), 65.

[10] Much of this comes from Borowski, O. (1992). Agriculture. In D. N. Freedman (Ed.), The Anchor Yale Bible Dictionary (Vol. 1, p. 97). New York: Doubleday.

[11] Arndt, W., Danker, F. W., Bauer, W., & Gingrich, F. W. (2000). A Greek-English lexicon of the New Testament and other early Christian literature (3rd ed., p. 895). Chicago: University of Chicago Press.

[12] (This resource is no longer online.)

[13] Arndt, W., Danker, F. W., Bauer, W., & Gingrich, F. W. (2000). A Greek-English lexicon of the New Testament and other early Christian literature (3rd ed., p. 161). Chicago: University of Chicago Press

[14] Knight, ed. (n.d.). Knight’s Mechanical Encyclopedia (p. 1163). Perseus Digital Library.



[17] Arndt, W., Danker, F. W., Bauer, W., & Gingrich, F. W. (2000). A Greek-English lexicon of the New Testament and other early Christian literature (3rd ed., p. 161). Chicago: University of Chicago Press.


[19] This resource is no longer available online: Crop Residue Collection for Field Grazing factsheet, Farm business Management, Sasskatchewan Ministry of Agriculture.

[20] Bouasker, M. (2014) Physical Characterization of Natural Straw Fibers as

Aggregates for Construction Materials Applications: Materials 7, 3034-3048; doi:10.3390/ma7043034


Hanson, Donna Guske, and Carlson, John E., (2004) Alternatives to Agricultural Burning: Agricultural Practices to Help Eliminate or Reduce The Need to Burn/Definitions.,( p. 9), The State of Washington, Department of Ecology.

  • [22]This resource is no longer available online: Crop Residue Collection for Field Grazing factsheet, Farm business Management, Sasskatchewan Ministry of Agriculture.


[24] Whittaker, 64.

[25] ibid

[26] Ibid., 69.

[27] Ibid., 69.

[28] Ibid., 64.

[29] Whittaker, J. C. (2000). Alonia and Dhoukanes: The Ethnoarchaeology of Threshing in Cyprus. Near Eastern Archaeology, 63(1–4), 65.

[30] Seven Brides for Seven Brothers