Pasture Tissue Testing for Nutrients

Thursday, August 06, 2020

Tissue testing of pastures can be a useful way of determining whether a plant has adequate levels of nutrients, particularly trace elements. This test will determine the plants ability to access nutrients at the time of sampling. It is not possible to rely on visual symptoms for nutrient deficiencies alone as these can often be confused with disease or other stresses. Once the deficiency is severe enough to show as physical symptoms there can already be up to a 50% reduction in growth. Therefore plant tissue testing in late winter/early spring should be used as a regular means of monitoring opportunities for improved pasture growth and performance.

If a deficiency is identified it may however already be too late to get any significant benefit this season, however nutrients could be applied early next season to maximise the benefits.

The most important elements that can be monitored using plant tissue analysis include copper, zinc, manganese, sulphur and phosphorus. Some other elements can also be deficient in some districts and soil types, such as molybdenum.

Remember to properly wash your hands before sampling. Use disposable gloves to avoid possible contamination, particularly if your hands have come in contact with fertilisers, copper or galvanised surfaces.

  • Grasses should be sampled before early jointing and legumes before flowering.
  • Collect samples early in the week, so that the laboratory analysing your samples can receive and process them within the week. Consider using a courier to speed up delivery of samples.
  • Avoid sampling if the pasture is stressed, including waiting 14 days after herbicides have been applied.
  • For grasses, sample the youngest fully emerged leaf blade. Collect at least 100.
  • For legumes, sample the youngest open leaves. These are generally very small, so 200 may be required to get sufficient material for testing.
  • Collect samples in a paper bag NOT a plastic bag.

There are a number of laboratories that can analyse samples, including Australian Precision Ag Laboratory in S.A.