Sample each soil type/management unit separately, according to these simple rules.

1. Identify a 5 x 5 square metre area and ensure you can locate it each year using GPS or fenceline markers. Make sure that the area is reasonably representative of the typical pasture growth for that soil type. Avoid sheep camps, areas near water points and waterlogged areas.

2. For each soil type take 25–30 soil cores to a depth of 10cm (7.5 cm in Tasmania) from within the 5 x 5 square metre area. The depth is critical as the interpretation of the soil test results is based on a sample of this depth.

3. Air-dry the samples and send them to an accredited laboratory straightaway.

4. Sampling. You may need to wait until at least 10mm of rain has fallen if sampling through normally dry periods. However, avoid sampling immediately following the break of a drought as available nutrients spike to abnormally high levels.

5. Avoid wet conditions when sampling.

6. When comparing soil test results over time, sample at about the same time each year. Soil tests should be taken regularly over time to track results. Use the same lab each time to ensure consistent results.

7. Test before fertiliser is applied or at least 6-9 months after the last application. Adjust application rates accordingly (see procedure 7.1 in Grow More Pasture).

Soil testing

Sample each soil type/management unit separately. Having information on every paddock would be ideal, but if several paddocks are on a similar soil type and have been managed in a similar way, a test from one paddock can be used as a guide for the other paddocks. Take separate samples from within the same paddock if there are vastly different soil types in a paddock or one area of the paddock has noticeably poorer pasture growth.

Send the samples to an Australian Soil and Plant Analysis Council (ASPAC) accredited laboratory as soon as they are taken. Check the ASPAC website for a list of laboratories: www.aspac-australasia.com. To find a lab, go to the section on the ASPAC website titled Certified ASPAC Labs. Make sure the tests being conducted on your soil samples are ASPAC accredited.

Sub-soils can also be sampled to monitor pH and aluminium if problems are suspected. This is important in order to determine if sub-soil acidity will affect survival of sensitive species such as lucerne or phalaris. For each soil type/paddock, take six soil samples from a depth of 30–40 cm or the top of B horizon in duplex soils. Use a shovel to dig down to this depth and take a handful of soil to test.

Many fertiliser companies and rural merchandisers can make soil sampling easier for you, and help interpret the results of the analyses.