Your soil is an asset. Discovering what makes your soils tick is the first step in creating a fertiliser plan that is practical, sustainable and most importantly economical.
Fertiliser is a major driver of farm productivity and profitability, however if managed incorrectly can be costly. This is precisely why soil testing is so valuable. It allows you as a farmer to identify what inputs are needed to drive production and then invest in those inputs.
How should you test your soils?
To ensure maximum value from soil testing it needs to be done correctly.
CSBP research has proven that a pogo stick or 20-30mm wide drill is ideal for carrying out soil testing.
CSBP recommends testing in 10 cm deep increments with a 9:1 ratio of inter-row to in-row cores, taking at least 20 cores from each site. For example 18 cores will be taken from the inter-row and two will be taken from in-row. Taking this number of cores per sample will reduce site variation and provide robust, reliable and consistent information.
Using an incorrect sampling method can return results which are inaccurate and potentially costly.
Figure 1 shows a comparison of three different soil sampling procedures; a standard shovel a standard soil pogo and an air operated drill. All three samples were sampled at the same location on the same day.
As can be seen from the above potassium (K) results the sampling method can play a huge part in the results returned. In this situation incorrect sampling methods such as using the shovel have returned incorrect results which have the potential to negatively impact crop yield and profitability.
Subsoil sampling is highly recommended
As a result of recent research, CSBP is discovering that testing to a depth of at least 30 cm is providing us with the best information to make the most accurate recommendation’s possible. This is why we are encouraging farmers to look deeper into their soils to discover more critical information.
Why test to depth?
While testing 0-10 cm has been standard practice and can tell us a lot about your soil. It simply doesn’t tell the entire story. Nutrients like Nitrogen (N), Potassium (K) and Phosphorus (P) can accumulate deep in the soil and can alter a fertiliser recommendation. Likewise testing deeper for soil constraints is as valuable. Limitations like low p.H, High Aluminium, salinity (EC), sodicity can be identified by subsoil sampling. All these factors impact on our decision making when creating an appropriate fertiliser recommendation. Information that is impossible to capture in just a 0-10 cm soil sample.
Planning your soil testing program
If management decisions are going to be made based off this information, it needs to be accurate. That is why it is worthwhile taking the time to create a soil testing plan designed to add value to your business. If you are looking for assistance in creating a soil testing plan your best bet is to contact your local CSBP area manager. They will assist you through the entire process from creating an appropriate soil testing program right through to interpretation of results, nutrient recommendations and follow up support.
Take home messages
• Contact your local CSBP Area Manager for assistance.
• Get sampling!
• Sample to depth.
• Use a consistent and correct soil testing process.