Sampling Basics
Selecting a representative sample is vital to accurate results. We help you by giving you advice for selecting a seed and grain sample and the quantity needed.
*Some certificates require samples to be taken by an accredited sampler. Find out how to become an ISTA accredited sampler.
Taking a Representative Sample
In seed and grain laboratory testing, small samples are analysed as representing the entire lot from which they were taken; "Representative" being the key word. Most seed and grain sheds have staff who are properly trained to take representative samples. However, if you don’t have staff trained in taking samples, we offer an accredited training course.
It is worth highlighting some of the important aspects of selecting a sample. Seed and grain lots are dynamically variable – they vary over space and time. Samples drawn from the bottom of a stack or the hot side of a silo may be quite different from samples drawn from elsewhere. Likewise, a sample that is left in a hot car may bear little resemblance to the product in the silo from which it was drawn. Equally, a test result on a sample from a year ago will not be the same as a fresh result.
To learn more about selecting a representative sample, you and your team can take our Accredited Sampler course - please contact us to make a booking.
The ISTA Sampling Calculator is a great tool to help verify sample size, lot size and more.
How to take a representative sample
To ensure a representative sample:
- Take lots of sub-samples randomly from all parts of the seed or grain lot and combine them to make up the sample that you send to the laboratory.
- Be sure to give the the sample an identification that will link it to the seed lot that you need tested.
- Complete the Request for Analysis form.
- Package the sample carefully with the Request for Analysis form and deliver or post it to the AgEtal Laboratory.
Sample Quantity Requirements
Sample Quantity Requirements
When drawing a sample: Refer to the Sample Quantities table below to see how much is required for testing. If the kind of seed is not listed, either send a minimum of 1 Kg or contact the laboratory.
Another great tool is the ISTA Sampling Calculator, found here.
Purity and Weed Seed Searches
The standard quantity required for most seed tests, including Weed Seed Searches apart from Tasmania, is the minimum quantity for a purity test. Please note that these are examples. The laboratory can be contacted for further information.
Western Australian Weed Seed Searches must be sampled by an accredited sampler.
- Maize - 1000g
- Chickpeas - 1000g
- Soybeans - 1000g
- Sorghum - 1000g
- Sunflower - 1000g
- Mungbeans - 1000g
- Wheat - 1000g
- Barley - 1000g
- Oats - 1000g
- White French Millet - 150g
- Japanese Millet - 80g
- Panicum - 90g
- Signal Grass - 100g
- Canola - 100g
- Lucerne - 50g
- Ryegrass - 60g
- Buffel - 60g
- Rhodes Grass - 10g
- Panic - 20g
- Carrot - 30g
- Pumpkin - 1000g
- Onion - 80g
Germination, Vigour and Tetrazolium tests
Germination, Vigour and Tetrazolium tests on their own require one tenth of the minimum purity weight.
- Tasmanian Weed Seed Search - 2 Kg (all species)
- GTA tests - 1 Kg
- Mungbean Appearance, Oversoak and Charcoal Rot - 200g
- Popcorn Expansion 500g
