What is chaff worth?

5 November 2023 by
Seed Terminator, Kelly Ingram

About $1000/t.

Well first you’ve got to cut the crop, then bind it then stook it, and feed it into an ancient, noisy bit of gear that literally runs like a chaff cutter, then bag it and sell it to people who really really love their horse. I get itchy just thinking about it, and if petrol is the cheapest thing you put in a car, then chaff is the cheapest thing you’ll put in a horse!


If you’re just counting the value of the nutrients in the chaff that is coming out of the back of the header, it’s worth about Thirty bucks a tonne.

It used to be worth twenty bucks, but you know the drill.

Fertiliser has gone up in price in recent years, and thankfully we are starting to see some relief. What has this got to do with the value of chaff? Well crop residue contains nutrients, and when we return these residues to the soil those nutrients have value. Some harvest weed seed control tools involve removing some of the residue from the paddock, or redistributing it into narrow lines, and this comes at a cost.

A Seed Terminator, on the other hand, returns all of the residue to the paddock, and it does a pretty good job of distributing it evenly.

The main nutrients in cereal chaff, in order, are Potassium (K), Nitrogen (N), and it’s a dead heat between Phosphorus (P) and Sulphur (S).  

In dollar terms, in a tonne of cereal chaff there’s about $20 of K, $8 of N, $2 of P and $0.50 of S at current fertiliser prices. That all adds up to about $30 of nutrients per tonne of chaff.

As you can see, two thirds of the nutrient value is K, and some soil types have luxury levels of K. Farmers with these soils don’t need to apply K fertiliser, and probably won’t need to for a long time. If you’re one of these farmers, you could say that there’s $10 worth of nutrients in a tonne of chaff, because you don’t value the K.

What does this mean in dollars per hectare?

If you’re crazy enough to measure the different residue fractions that come out of the back of the harvester, you’ll find about 15% of the wheat residue is chaff off the sieves. This is the fraction that goes into a Seed Terminator, or a chaff cart, or a chaff line / deck.

If you have a 3t/ha wheat crop, then you have 450kg/ha of chaff, which is worth $13.50/ha. This is the amount of money that could be lost if using one of the tools that remove or re-distribute the chaff fraction. These are still good tools, it’s just that we must be aware of this nutrient cost.

Canola is similar to cereal, but there’s a bit more N and a bit more S in the chaff, amounting to about an extra $4/tonne.  The other thing that we know about canola is that you get a lot more chaff per tonne of grain harvested. The harvester tends to smash canola into little pieces. 

Given that canola generally yields less than wheat, but we get more chaff per tonne, the nutrient cost per hectare for canola and wheat are pretty similar in any given year.

Legumes – you guessed it, more N, twice as much in fact, so now our chaff is worth $40/tonne. Once again, legumes often produce more chaff per tonne, and usually yield less than wheat, so the ballpark nutrient value of chaff per hectare is pretty similar to wheat.

Rule of thumb

What does this all boil down to. In simple terms, for every tonne of grain harvested, there’s about $4.50 worth of nutrients exiting the harvester in the chaff fraction. It used to be $3 in the good old days (2020!), but now it’s $4.50. If you don’t value the K because you’ve already got loads of it, then call it $1.50 per tonne of grain harvested.

If you’re doing sums on different harvest weed seed control tools, and you want to put a value on the chaff, this is it. Call it $5 if you want to round it off. Multiply this by your average wheat yield, and bingo.

If you ever think that running a Seed Terminator is expensive, then get yourself a couple of horses! And if you’re anything like me, you’re think of a business opportunity to turn $30 worth of nutrients into $1000.

The Terminator Agronomist
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Please note this advice is general in nature and not based on your specific circumstances.

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