Collecting Soil Samples

To be effective, a soil test needs only one thing above all else – consistency! In the beginning, choose the area(s) of the property to sample and keep going back to them with every round of testing. And follow the same path across your chosen area and use the same sample depth each time.

The objective is to look for a ‘Representative average’ for a particular area. Observe where soil varies in colour/texture, cropped or fertilised differently. Look for distinct changes in Land use, such as pasture on hills, cropping or flats. Most importantly you need to use the right implement and sample to the right depth.

How Many Samples?

One sample can cover up to 100 acres, but remember that soil is extremely variable, so you are looking for a good average over a particular area. Choose the area and number of samples by looking at soil colour and soil texture, topography and management history.

If you have mainly one type of soil and the same topography across the whole property, then one sample covering the whole property may be enough.

However, even if the soil is fairly consistent, there could be a distinct change such as pasture on hills and cropping on flats. Alternatively, there could be distinct changes in the soil. In cases like these, you will need a sample from each distinct ‘section’ of the property. But follow a set path when you collect the soil so you can come back and re-test every one or two years (at the same time of year). In this way you will be better able to track any changes that occur over time.

Collecting the Sample

Remember, you are looking for results that give a reasonable picture of the soil within the root zone of the plants. So the depth you sample should match the depth of the feeder roots.

For pasture this is 0-10cm, for field crops and vegetables – 0-15cm, for tree and vine crops – 0-25cm. 

If you are taking samples of the profile greater than 25cm you should separate them into two or more sections - say 0-15, then 15-25 and 25-40cm (as the case may be). 

It is especially important to divide samples into separate profile sections if there is a clear change from topsoil to subsoil. In cases like this, the surface layer should be tested using the standard analysis and taken with a stainless steel core sampler.

The second layer can be tested with the Gypsum & Lime analysis and cores taken from the bottom of holes dug to the level at which the colour/texture change occurs.

Whatever depth you use, make sure it is clearly marked on the information sheet sent in with the sample.

In all cases, the best tool to use is a stainless steel core sampler. You need to collect soil from 20 – 30 spots across the paddock or area to be tested. Mix the soil VERY thoroughly in a clean plastic bucket and retain about 250g for testing. In place of a purpose built core sampler, many people find a simple 'apple corer' is adequate for the occasional sample.

NB. Only use stainless steel samplers. Other metals can produce distorted results for Iron, Copper or Zinc, etc.

When choosing the spot to take each soil core, avoid areas near fences, gates, troughs, livestock camps and tracks. Also avoid dung & urine patches and areas where hay has been fed out – anywhere that may distort your result.
 
Research shows that a zigzag path gives the most reliable result, but choose your path carefully, so you can easily go the same way again next time.

Lastly, don’t forget to complete the information sheet with important sample and site details. These include:

• Land use (up to 3 per sample, eg. Carrots, Cabbage and Leeks)
• Area sampled (hectares or acres)
• Sample depth (cm)
• Topography/ Drainage/ Rainfall/ Irrigation
• Application History – Date & Quantity of: Lime, Dolomite, Gypsum (tonnes/ha) & Trace Elements: Cu, Zn, Fe, Mn, Co, Mo, B (Kg/ha)

Wet Samples

It is no good to take the soil sample if the soil is saturated, (that is, if water is dripping out when you hold a handful of soil in your hand).

If the soil is just damp, but not saturated, it can be put on a plate or in a paper bag, and let dry either in the sun or in the oven over night with the absolute maximum temperature between 45° and 60° Celsius.

Sending a Soil Sample to SWEP

We can send you a sampling kit, but if you already have your sample, you can follow these instructions (links will open a new window):

1. Follow the instructions above to collect the sample.
2. Put your sample (250g to 300g only) into a strong, sealed plastic bag (such as a ‘Ziploc’ bag) and write the sample ID name on the outside with a felt-tip pen.
3. Go to our Forms page and print the relevant Sample Information form for your sample type (soil, plant tissue or water), fill in the details and enclose it with the sample.
4. Pay for the tests you want either by writing your credit card details on the sample information form you just printed (step 3), or by using our Online ordering page.
5. If you are not in Australia, please read the information about Sending samples from Outside Australia and write the address and Quarantine permit details clearly on your package.
6. Send the sample to us by mail or (if you are outside Australia) via International Airmail (do not use a courier service)

If you have any difficulties or need more information, please feel free to Contact us.

We accept either Cheque, Credit Card or Online Payment - Do Not send Cash in the Mail!

Your local Post Office is probably the best to advise on how to pack and label the sample.

For customers within Australia, the address to send samples is :

SWEP Analytical Laboratories
PO Box 583, Noble Park, VIC 3174
Australia.

For customers Oustide Australia : You need to use our Street Address (Not the one above) and also include additional details on the package (For Quarantine purposes) if you are sending samples from Outside Australia.