Here is a simple guide to taking soil samples.
In the image to the right is a paddock that we've highlight the areas to avoid such as the fences, gate, underneath the power lines, under the trees and around the trough. In the aerial photo you can also see dark green areas where animals have deposited manure or urine. These areas should also be avoided.
We've picked fence posts that we use as markers for walking the transects along which we take the soil samples.
This paddock is small at around 0.75 hectares. It has a uniform soil type, aspect, slope and has historically had the same management practices applied. As such the soil sampling can cover the entire paddock.
To sample the soil we use a soil corer.
These can be purchased from agricultural suppliers and make obtaining regular samples easy and accurate.
To collect your soil samples walk the transect stopping at intervals to take a sample.
Measure where 10 cm is to determine where to cut
Cut out the top 10 cm of the soil
Add the sample to a bucket
Collect at least 15 samples
Bag the entire sample in a ziplock bag
Squeeze air out of the bag and seal it
Ensure the ziplock bag is properly sealed and is airtight.
Removing air from the bag helps reduce microbial decomposition of organic matter which would otherwise increase nutrient availability of the sample and give a falsely higher result.
Label the bag with:
Post your sample to the soil testing laboratory. The sample should be taken and sent to the laboratory as soon as possible. If you are unable to send the sample for a day or two, then store it in the fridge until it can be posted. Try to send the sample early in the week to avoid it sitting in the post over the weekend. Removing air from the bag and cool storing reduces microbial decomposition of organic matter which would otherwise increase nutrient availability of the sample and give a falsely higher result.