Soil testing
Which laboratory?
Soil test packages
- Basic
- Grazing
- Cropping
- Horticulture
Specialist tests
- Pesticide residues
- Heavy metal contamination
Customer service units
Contact the customer service unit at Wollongbar for assistance. The soil sampling kit is available from any customer service unit.
Feedback
- Wollongbar: wollongbar.csu@dpi.nsw.gov.au
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Soil is the most important resource in agriculture. Understanding and maintaining the health of your soils will provide you with a foundation for sustainable agriculture and increased productivity. Diagnostic and Analytical Services provided by NSW Department of Primary Industries (NSW DPI) can assist you in maintaining the health of your soil.
Our laboratories are NATA-accredited and independent, giving you consistent, reliable results. Our laboratory staff are backed by NSW DPI’s extensive advisory service, providing the complete 'farm health' package for your enterprise.
Why should I have my soil tested?
There are two reasons why you should have your soil tested:
- to get a snapshot of the chemical properties of the soil in a paddock - this is usually done prior to the sowing of a crop or pasture.
- to monitor changes in soil properties.
Tests available
Our soil testing laboratories can undertake a range of soil analyses to assist you in determining the nutrient and trace element requirements of your soil. In addition, the laboratories can undertake specialist testing for pesticide residues and heavy metal contamination.
Choosing the appropriate soil test package
NSW DPI offers four soil test packages (basic, grazing, cropping and horticulture). If you have not previously had soil tested we suggest you talk to your advisor, district agronomist, district horticulturist or phone our customer service unit on 02 6938 1957 to determine the most appropriate package for your needs. In addition to our soil test packages, over 50 types of soil tests are available on request. Please contact our customer service unit for current prices.
Soil test packages available
|
Basic |
Grazing |
Cropping |
Horticulture |
|---|---|---|---|
| pH (CaCl2) | pH (CaCl2) | pH (CaCl2) | pH (CaCl2) |
| pH (water) | pH (water) | ||
| EC (water) | EC (water) | EC (water) | |
| Available phosphorus (Colwell) | Available phosphorus (Colwell) | Available phosphorus (Colwell) | Available phosphorus (Colwell) |
| Phosphorus buffer index | Phosphorus buffer index | ||
| Available sulfur (KCI40 |
Available sulfur (KCI40) |
Available sulfur (KCI40) |
Available sulfur (KCI40) |
| Exchangeable cations (Gillman & Sumpter) | Exchangeable cations (Gillman & Sumpter) | Exchangeable cations (Gillman & Sumpter) | |
| Walkley & Black organic carbon | Walkley & Black organic carbon | ||
| Chloride | |||
| Total Nitrogen | Total Nitrogen | ||
| Extractable Boron | |||
| DTPA extractable Copper, Iron, Maganese & Zinc |
The Grazing package provides general information and is usually quite sufficient in most grazing applications, however, if you know from previous testing that you only need to monitor phosphorus and sulfur levels then a Basic package may be adequate.
The Cropping package would be a better choice for cropping and horticulture circumstances and also where more detail is required than in a grazing situation.
The Horticulture package contains all the features in the Cropping package, plus testing for the trace elements boron, zinc, chloride, copper and manganese. This package will be of most use to horticulturalists. If other trace elements are needed leaf/tissue analysis may be more appropriate than soil tests.
In cropping areas a deep nitrogen test may be required. This test requires special sampling and packaging for transportation to the laboratory. Please talk to your advisor or our Customer Service Unit before sending samples for deep nitrogen testing.
Preparing and submitting samples
The soil sampling kit
The soil sampling kit provides all you need to submit your samples to our laboratory. The sampling kits are supplied free of charge. They are available at NSW DPI district offices or through our customer service units.
The kits are easy to use:
- Collect your soil sample and place in the container provided (see the detailed instructions below).
- Fill in the sample submission form (included with the kit) and tick the box for the tests that you require.
- Place the soil sample and the completed form in the reply paid mailing cylinder and post to the laboratory at Wollongbar.
- The results will be sent to you on the completion of testing, along with an invoice for the laboratory charges.
Tools required for sampling
- Soil corer or spade
- Buckets
- New plastic bag or sample container (located in soil kit)
- Labels if more than one sample is collected
- Record sheet to record sample site and sample.
Remember a soil test is only as good as the care taken in sampling. Tools and equipment should be clean prior to sampling.
Taking a soil sample
Look at the soils in the area you intend to sample. Submit a separate soil sample from each soil type (eg clay, loam or sand) and from paddocks that have been managed differently, because these factors affect fertiliser needs.
For each sample, thoroughly mix a minimum of 20 soil cores (see following paragraph) in one bucket (the more cores taken the more reliable the sample). Fill the container supplied in the kit with the sample from the bucket. If you have collected multiple samples you can submit your samples in 500 gram bags to the laboratory. Make sure samples are clearly labelled.
Soil cores should be collected at 0-10 cm depth. Avoid collecting the surface material such as leaf or organic matter. Deeper cores may need to be taken for the investigation of subsurface acidity and salinity or for larger horticultural crops (please contact your advisor for this advice).
Once the samples have been collected they should be sent as soon as possible to the laboratory for analysis.
Soil core collection methods
A map and written plan of the soil sampling area is essential for interpreting results and any subsequent testing. It is recommended that soil cores be collected along a fixed transect (e.g. 1 and 2). This method allows for re-testing and better monitoring of changes in fertility than random sampling. In areas where tree crops are planted samples should be collected along rows.
To obtain representative samples, do not sample from unusual sites such as:
- stock camps
- manure patches
- gateways
- dams or water troughs
- feedout areas
- old fertiliser stockpiles
- paddocks that have had fertiliser applied in the last 3 months
Interpretation
Interpretation of soil test reports requires specialised knowledge of local conditions and crops. Our laboratory reports therefore do not include an interpretation. We strongly recommend that you consult one of NSW DPI District Agronomists or Horticulturalists or another advisor to interpret the results. See general information on soil test interpretation.
The kit complements NSW DPI’s SOILpak series of soil management manuals. These manuals are designed to provide a range of best soil management practices to optimise crop and pasture yields. Talk to your District Agronomist to find out which SOILpak manual suits your enterprise.
|
Test |
Application |
|---|---|
| Soil pH | pH is a measure of acidity and alkalinity. Soil pH can affect nutrient uptake. |
| Electrical conductivity | Electrical conductivity is an indirect measure of salinity. Many plants are affected by high soil salinity. |
| Available phosphorus | This test is useful in assessing the need to fertilise crops and pastures with phosphorus. |
| Phosphorus buffering index (PBI) | This test is a measure of the soil's ability to tie up phosphorus. It can assist in determining fertiliser requirements. |
| KCI extractable sulfate sulfur | Test used to determine sulfate availability in soils. |
| Exchangeable cations and Cation Exchange Capacity (CEC) | The major exchangeable cations are calcium, magnesium, potassium, sodium and aluminium. CEC is a major factor affecting soil structure, nutrient availability, soil pH and also the soil's response to fertiliser. |
| Organic carbon | Organic carbon is a measure of the organic matter level of a soil. This in turn is very important for soil structure and plant nutrient intake. |
| Chloride | Chloride is the most commonly occurring soluble anion in Australian soils. the importance of this anion in land-use assessment is due to its possible accumulation in soil profiles to levels that are detrimental to plant growth. |
| Total nitrogen | Total soil nitrogen provides an indication to the soil's long term nitrogen supplying capacity. |
| Boron, hot CaCl2 extractable | Test used to obtain an index of soil boron status for plant growth. |
| DTPA micronutrients (Fe, Mn, Zn, Cu) | Measures plant-available forms of these elements. |
Other tests that may be required include:
| Pesticide residues (Organochlorines, organophophates, synthetic pyrethroids) | Useful if pesticide build-up is suspected, and for dip site remediation. Used by organic growers seeking certification. |
| Total carbon | Carbon is the organic material in soil which improves moisture holding capacity, increases soil structural stability and protects soil from erosion. Carbon:Nitrogen ratio is used when making compost from organic material. |
| Full ICP scan (AL, Ca, B, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, Zn, As, Cd, P, Na, S, Co, Mo, V) | This test will assist in identifying any nutrient/metal deficiencies or toxicities in your soil or organic fertiliser. It is important to check for metals in organic fertilisers, particularly those sourced from human and animal waste. |
| Nutrient ICO scan (B, Ca, Cu, Fe, K, Mg, Mn, Na, P, S, Zn) | A nutrient scan will assist in solving nutrient deficiency or toxicity problems that you may have with your soil or organic fertiliser. |
| Mineral nitrogen | Nitrogen requirements before planting a crop. |
Checklist
Plan your soil testing with your local District Agronomist, Horticulturist or advisor.
Collect samples with clean equipment.
Send samples to the laboratory as soon as possible after collection.
Discuss your results with your advisor or local District Agronomist or Horticulturist.
Which laboratories conduct the soil tests?
Soil testing is conducted at our laboratories at Wollongbar Primary Industries Institute - see contact details.
Customer service units
Contact the customer service unit at Wollongbar for assistance. Note that the soil sampling kits are available from any customer service unit.
Feedback
Your feedback is always welcome. Our laboratories operate to ISO 17025 standard, and we will respond to all comments or criticisms of our service.