NU-test Sampling Technique
The general rule when sampling for nutrient uptake (sap) analysis is to take actively growing parts from randomly selected plants from a representative area of the crop, or from plants that are representative of the crop (eg. tree crops). For NU-test results to be meaningful, a consistent sampling technique is important.
Procedure
Collect samples at a consistent time of day, preferably early in the morning.
Samples must be collected from the same area and at approximately the same time for all subsequent samples. It helps to mark out the sampling area.
Ensure a representative section of the crop is selected (e.g. 1-2 hectare).
For random sampling follow a zig-zag (W or Z) pattern through the selected area.
If the crop covers large areas with distinctly different soil properties that can be fertilised independently, and the crop appears different in these areas, they should be sampled independently.
Avoid areas that do not represent the majority of the crop. These include:
- fence lines or tree lines
- high or low points within the paddock
- culverts and irrigators
- fertiliser dumps or burn off sites
- variations in soil type (more than one sample may be necessary)
- anything that is not indicative of the overall paddock
- Irrigation overlaps
- variation in growth stage
For information on which plant part to sample, refer to specific sampling instructions for individual crops provided below.
Sample Preparation, Transport and Care
- Prepare the sample as per the specific sampling instructions.
- Place the sample in a clean, dry plastic bag for transportation. Do not use paper, as dehydration will occur. The sample must be refrigerated until mailing or delivery to the laboratory. An esky should be used for transportation from the paddock, a fridge for short term storage. Do not freeze the sample or put it directly on ice bricks.
- Label each sample carefully and use the labels provided through the link at the top right hand side of this page. When sending more than one sample, make sure that the numbers on the bag correspond with the numbers recorded on the label in the same row as the sample details. Contact the laboratory if you would like a sample label book that provides a carbon copy of the label for you.
- When mailing samples, we advise to wrap the plastic bags containing the sample(s) in newspaper for insulation.
Mail samples in an express post bag to:
Serve-Ag Analytical Services, P O Box 690, Devonport Tas 7310
For more information on NU-test sampling email Serve-Ag at sas@serve-ag.com.au or call 03 64 986 800
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