Soil testing and observation is an important part of a production system. It is used for predicting nutrient requirements, plant selection, management techniques and for investigating areas of a paddock that are not performing well or where plant growth appears to be hindered.
Soil sampling needs to be undertaken in a calculated fashion to ensure that most representative results are obtained. The most important aspects of soil sampling that needs to be managed are timing, location and depth.
Timing - if you are sampling for nutrient availability the best time is just before you plant the crop as an indicative measure of this space in time.
Location - the location of the soil tests should be representative of the whole field in the case of the nutrition test or be site specific for trying to assess a specific soil issue or constraint . For example, in a poor patch or a good patch in the paddock, where plants are showing a point of difference.
You should avoid tracks/roads, watering points, trees, headlands and wheel tracks.
Depth - the soil sampling depth is important as the top 30cm is where the greatest proportion of nutrients are concentrated and where root density is at its greatest. However soil roots are able to penetrate to a depth of 2m and beyond and it may be necessary to sample to this depth if you are trying to identify a particular soil constraint impacting on production in your paddock.
You can sample a paddock in two main ways. Firstly, using a spade or surface sampler and secondly using a deep corer or soil auger.
Central West Local Land Services Neroli Brennan shows you how to do a simple in-field spade inspection.
