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Plant & Soil Testing

To produce a quality crop, make sure you get a regular scientific assessment of the nutritional status of your soil, plant tissue and water quality.

PGG Wrightson works with New Zealand’s largest privately-owned testing laboratory, Hill Laboratories to offer a range of soil, leaf and water testing services. We can provide you with Hill Laboratories’ detailed guidelines on how to take the soil, leaf or water samples. And we can help you interpret the results to prepare a crop specific fertiliser programme.

Simply contact your local PGG Wrightson representative for details about this service.

Soil Testing

Soil tests measure only a fraction of the total pool of nutrients available to plants (immediate and long term). Standard NZ methods of sampling and analysis are used, so results are meaningful and relative to plant growth in our conditions.

A single soil test is of limited value as it is essentially a snapshot in time of a dynamic environment. Trends in soil test values over time will give a better indication of how well your fertiliser programme has worked. Even when nutrient status is at optimum levels, other factors can influence the plant’s rate of nutrient uptake. In order to obtain a more complete picture of nutrient status, soil testing should be complemented by plant testing.

When taking a soil sample, reduce the likelihood of variable test results by:
  • Dividing the land into areas of the same soil type, topography and management practice
  • Avoiding areas of abnormal fertility such as dung patches, gateways or water troughs
  • Waiting until at least three months after the last fertiliser or lime application
  • Sampling at the same time and from the same area each year
  • Sampling to the standard depth
  • Monitoring soil test trends over time
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Leaf & Plant Testing

Plant analysis, or leaf testing, is a very useful in complementing a soil analysis. A soil test shows what is available to the growing crop, while a leaf test shows what has actually been taken up by the crop, providing a more reliable assessment of crop nutrient status.

Leaf tests can be used in two ways:
  1. To routinely monitor nutrients to help sustain optimum levels and thus avoid nutritional disorders
  2. Identify nutrient deficiencies, toxicities or imbalances. Low plant nutrients are often due to low soil nutrient levels, but this is not always the case. 

The results will need to be interpreted according to plant species, part of plant sampled and growth stage of the plant. Your local representative can assist you with this interpretation.

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Water Testing

Water can be analysed for its suitability for domestic, stock or irrigation purposes. Your local representative can arrange for a series of tests to ensure water meets the New Zealand drinking standards and/or EUREP GAP protocols for irrigation water for fresh fruit and vegetables.

 Water quality tests available include:
  • A comprehensive chemical and microbiological water testing kit
  • Testing kits for just chemical testing, faecal coliform testing and E. Coli testing
  • Testing for metals such as fluoride, arsenic, chromium, cadmium, lead, or mercury
  • Testing for pesticide residues
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Identifiying Pests & Diseases

If you’re struggling to identify a specific pest or disease, your local representative should be able to help you with the correct classification. However, in unusual circumstances, for example with a fungal rot that could have one of many sources of origin; we can enlist the assistance of a specialised service such as AsureQuality.

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Need Help?

It is very important to take testing samples correctly; please ask your local representative for sampling instructions specific to your growing situation. 

These instructions, a full list of the available tests and fees are also available online at www.hill-labs.co.nz.

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