Making More from Sheep Australian Wool Innovation Limited Meat & Livestock Australia
MODULE 6 : Healthy Soils
Procedure 6.3
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Background
information

Standard soil fertility tests can provide a lot of information about your soils and differences between paddocks, no matter what your attitudes and preferences about using fertilisers. Soil nutrient deficiencies and imbalances can have a compounding impact — these soils are likely to have poor plant and root growth, low groundcover and litter levels and, therefore, a lower level of soil organic matter supporting fewer soil organisms such as bacteria, fungi and earthworms. Healthy biodiversity in soil organisms is also important to suppressing pathogenes which cause root disease.

This procedure deals with the issues of taking a soil test, interpreting the results, and identifying soil health problems such as soil acidity or sodicity. Fertiliser decisions, which are essentially about pasture growth and maximising profit, are dealt with in procedure 7.1 in Grow More Pasture.

 

At a Glance
Use soil tests to help monitor nutrient levels and soil health on different areas of your property
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Key decisions, critical actions and benchmarks

Even without a laboratory test, the number of earthworms present, and/or the ‘look, smell and feel’ test can give an indication about soil health. Tool 6.3 explains how to do these tests.

Take soil samples for testing

Tool 6.4 provides the directions for taking a soil sample for analysis at an accredited laboratory.

Standard soil tests provide an analysis of:

  • Texture, colour, pH (usually in water and in calcium chloride (CaC2)) and electrical conductivity (EC)
  • Phosphorus (P), Phosphorus Buffer Index (PBI), potassium (K), sulphur (S) Calcium (Ca), magnesium (Mg), aluminium (Al) and sodium (Na)
  • Calculations of cation exchange capacity (and Na percent of cations), Ca/ Mg ratio and Al saturation.

Sub-soils can also be sampled to monitor pH and aluminium. This is important to determine if sub-soil acidity will affect survival of sensitive species like lucerne or phalaris seedlings. For each soil type/ paddock, take six subsoil samples from a depth of 30–40 cm or the top of the B horizon in duplex soils.

Interpreting soil tests

Interpreting soil tests as part of developing a fertiliser strategy is discussed in tool 7.3 in Grow More Pasture which considers the use of phosphorus, potassium, sulphur and nitrogen.

Tool 6.5 is provided to help interpret soil tests for any soil health problems (acidity, sodicity, salinity and trace elements) on your farm.

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Read

Soil Analysis, an Interpretation Manual: edited by K.J. Peverill, L.A. Sparrow and D.J. Reuter (CSIRO Publishing: Collingwood).
view: www.publish.csiro.au/pid/1998.htm

Towards Sustainable Grazing – the Professional Producer’s Guide, Chapter 3, Soil Health and Nutrients: a collation of proven best practices for modern grazing enterprises in southern Australia. Order your copy from MLA by:

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Making Better Fertiliser Decisions for Grazed Pastures in Australia: This product comes in two parts: an informative booklet and a CD for developing fertiliser maps. Use the Farm Nutrient Loss Index tool (on CD) to create a farm map and assess the likelihood of fertiliser applications being lost from the site. Get your free copy of the booklet and software tool by:

Five easy steps to ensure you are making money from super phosphate. This booklet is relevant for the management of temperate legume-based pastures grazed by sheep and beef cattle on acid soils in southern Australia. Click here to download (1.4MB)

Soil Acidity: a wide range of fact sheets covering soil health issues (not just acid soils). Visit the NSW DPI website: www.agric.nsw.gov.au/ and search for acid soils.

Soil Acidity - A Guide for WA farmers and consultants (published by DAFWA) can be downloaded at: http://researchlibrary.agric.wa.gov.au/bulletins/31/

Dispersive soils and their management can be downloaded at: http://dpipwe.tas.gov.au/Documents/DPIW_DSM_Manual_April2009.pdf

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