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Eddie says a grain spear is sometimes used to take a sample of grain. Usually, however, samples are taken automatically by machine in the feed mill at the weighbridge.
The spear is sequential in that the slots open at the bottom first.
Eddie says having a sequential opening spear is important because if all the slots opened at the same time the grain entering the top slot would more than likely fall to the bottom of the spear, reducing the chances of getting a representative sample.
Taking a sample
To take a sample, he climbed up on the heap of grain. Making sure the slots in the spear were closed, he drove the pointed end down vertically into the heap.
He then opened the slots and listened for the sound of grain entering the spear. When the spear was full, he closed the slots and lifted it back up out of the heap.
He placed a sample bag on top of the spear and tipped it upside down, releasing the contents into the bag.
Firstly, Eddie tested the moisture content of the sample. To do this, he used an electronic moisture analyser that uses infra-red technology.
This system works by sending a light-wave frequency through the grain sample.
The interaction of the waves with the water enables the equipment to determine the moisture content of the sample. An oven-based test is also regularly carried out to ensure the accuracy of the reading.
This is done by grinding down a sample of grain to flour, weighing the sample, placing it in a specific oven at a set temperature and length of time, and then re-weighing the sample once it comes out again.
Specific weight or hectolitre weight is a measure of grain for a specific unit of volume. To get the specific weight, Eddie used a condrometer, which is made up of three parts.
To carry out the test, he filled the first container with grain. He then placed a funnel on top, inverted the tube and placed it on top of the auxiliary chamber.
The funnel regulates the speed of grain flow into the auxiliary chamber.
A special brass plunger sits on top of the guillotine and this controls the speed of fall of the grain into the bottom chamber once the guillotine is pulled out.
The guillotine was then inserted again and any excess grain left above it was removed. Eddie then placed the chamber full of grain on a calibrated scales adjusted to allow for the weight of the steel condrometer and the result is expressed in kilogrammes per hectolitre (kph).
Screenings
Some buyers of feed grain also do a screenings test to measure the percentage of split, small, shrivelled grains, as well foreign material such as chaff.
A screenings test is particularly important for milling wheat, but also useful for feed.
To do this test, Eddie uses an automatic machine to shake and sieve. A 100g sample of grain is poured onto the top sieve and the machine can have a number of sieves fitted.
Once turned on, the screening machine shakes the tray for two minutes. Any material that passes down through the 2.25mm slots in the sieve represent the screenings.
This is then weighed to give the percentage screenings in the sample.
Grain quality testing
Eddie Young works in Charles R Wynne Ltd, a grain and agricultural merchant based in Kildare and Carlow.
Eddie says when assessing grain quality the first port of call should always be to judge the grain by eye – take a fistful of grain and assess the colour and how well filled the grain is.
Shrivelled and poorly filled grain may affect energy and feed values.
Simply smelling the grain and running it through your fingers will indicate how well filled it is and the moisture content – mould growth and clumping would indicate high moisture content.
Quality grain needs to be well filled, showing predominantly plump grains which contain the starch to provide the energy for livestock.
Good grain should not contain lots of weed or other seeds and neither should it contain other organic sources, such as rodent faeces or ergot.
The main tests we went through here are:
Moisture content
Eddie says dried grain is traded at 15% moisture. The closer a farmer can get to 15% the better. Moisture content has a significant bearing on quality, storage and sale weight.
According to Eddie, the moisture content in grain is very important because it is the basis on which a farmer gets paid.
For example, in Wynnes, if the moisture content is below 20%, the farmer would get a bonus but if the moisture content is above 20% a penalty will ensue.
Specific weight
This is the weight of a given volume of grain and gives a measure of the grain density. By using a condrometer you can measure how the grain fills a chamber without being packed in.
If the grain had a high moisture content, it would not pack as well into the condrometer and would have a lower kph than a drier sample.
Screenings
The size of the grain provides some measure of the level of its starch or energy content. The screenings test measures grain size or plumpness, or lack of it.
Narrow, poorly filled grains fall through the different sieves used in the test. Generally, for a good quality grain sample, there will be less than 2% screenings.
Values of over 6% indicate small poorly-filled grains.
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