The instructions below instructions are a very brief snapshot to encourage samples to be taken with the best chance of representing the paddock avoiding contamination.
Sampling practice is the single most important component to getting value from soil testing, and should be taken very seriously. Accurate analysis, interpretation and precise nutrient management can only occur with a quality representative sample.
1. Review your required tests. If guidance is required consult your local advisor/agronomist.
2. Determine an appropriate sampling plan.
3. Ensuring a representative sample is obtained.
a) Avoid unusual areas listed above.
b) Ensure all your equipment is clean.
4. Remove debris and plant material from the soil surface.
5. Take the required number of cores, aim for at least 25 cores per site, in an appropriate pattern (see below).
6. As a general rule, 8-10 inch rows and 1-inch corer, 1 in every 8 cores should be taken on a recent seeding row furrow and the remainder between the seeding rows.
7. Pool your cores in a clean plastic bucket, breaking the soil into small crumbs.
8. Mix the sample thoroughly in the bucket.
9. Place your representative sample into soil test bags and fill to the required line.
10. Ensure your equipment and bucket is clean before moving onto your next sample.
11. Shovels are not ideal, but if using a shovel ensure the sample is consistent down to the required depth (e.g. take a slice down the side not a V shaped “hole” sample).
12. If excess sample is collected ensure the sample is well mixed before sub-sampling into the bag, try to reduce the sample to around 250-300 grams to avoid excessive postage charges.
d) Uniform grid
Stable in the soil as it is a cation, but converts to Nitrate readily.
As pH declines (becomes more acidic) Aluminium levels can increase in some soil types. High Aluminium levels will affect root growth reducing their ability to explore large volumes of soil and therefore their access to nutrients and soil moisture. (Read the article on soil pH here)
PBI is a function of soil type. Generally as a soil contains more iron, clay and organic matter, the higher the PBI. (See article)