Maintaining Soil Quality of Grazed Pastures

Year of study:

1997-8

Lead Organisation & collaborators:

Department of Natural Resources and Environment

Contact:

Anne Crawford

DNRE

Project details

Objectives:

A suite of indicators were assessed for use in monitoring short and long term changes in soil quality under grazed pastures.

Hypotheses:

Key soil chemistry, physical and biological properties contribute to soil fertility and would provide a sound basis to assess the health of pastoral soils.

Basis of trial:

Use of soil property indicators to monitor short and long term changes.

Best available science assessment:

Overall score: 28

Overall rating: High

Objectives

Conceptual model

Study design

Soil analysis

Production & financial

Method reporting

Data analysis

Results reporting

Publication

4

3

4

3

1

4

3

3

3

Trial site details:

July 1997

Dry conditions

Site Rainfall Soil type
Ellinbank Warragul (BoM) 1026.8mm/a Krasnozem
Ellinbank Warragul (BoM) 1026.8mm/a Krasnozem
Ellinbank Warragul (BoM) 1026.8mm/a Krasnozem
Ellinbank Warragul (BoM) 1026.8mm/a Krasnozem
Strzelecki Korumburra (BoM) 1207.7mm/a Sedimentary
Loch Nyora (BoM) 1008.5mm/a Sedimentary
Nyora Nyora (BoM) 1008.5mm/a Sandy Loam
Mardan Mirboo North (BoM) 1020.3mm/a Sedimentary
Koonwarra Koonwarra (BoM) 951.8mm/a Sandy Loam
Tarwin Lower Tarwin Lower (BoM) 940.0mm/a Sandy Loam

Pre-trial management:

Site Type Management inputs
Ellinbank Dairy Medium
Ellinbank Dairy Low
Ellinbank Dairy High
Ellinbank Beef Low/medium
Strzelecki Dairy Medium/high
Loch Beef Low
Nyora Dairy High
Mardan Beef/sheep Low/medium
Koonwarra Beef/sheep Low
Tarwin Lower Beef Medium/high

Summary of key findings of trial:

These transects provided a snapshot of soil quality beneath grazed pastures. Soils were generally of good to high fertility, moderately acidic and reasonable CEC and organic carbon content.

Soil pH and carbon generally decreased with soil depth across this assessment.

Trend indicators, such as pH were appropriate for measuring short term change in soil fertility, as a result of farm management practices such as the application of lime.

Soil Sampling Method:

Initial sample July 1997. (Single bulked samples)

Transect lengths between 50-250m were taken at the sites. Soils were sampled at 0-2.5, 2.5-5 and 5-10cm at 30 points along the transect.

Duplicate 0-10 and 10-20cm samples were taken from 30 points each.

Sampled over two years 4-6 weeks after the autumn break (July 1997 and May 1998), and mid spring (November 1997 and 1998).

15 cores, 50mm diameter were taken at 0.6m depth on the transect. The cores were sub-sampled for chemical analyses at 02.-0.3, 0.3-0.4 and 0.4-0.6.

Stored at 2-4 degrees for no more than 4 weeks. Slaking and dispersion tests- 8 to 10 aggregates were selected and dried at 40 degrees.

The 0-10cm and 10-20cm samples were dried at 40 degrees and passed through a 2mm sieve.

Tested for:

  • pH (water and calcium chloride)
  • Electrical conductivity
  • Olsen and Colwell P
  • Colwell K
  • Available sulphur
  • Exchangeable Al
  • Oxidisable organic carbon
  • Total carbon
  • Total Nitrogen
  • Exchangeable cations

Ellinbank, Rutherglen and State Chemistry Laboratory

 

Reportage:

How results have been reported:

Technical report, Anne Crawford DNRE

How a copy of any relevant reports can be obtained:

Maintaining soil quality of grazed pastures: final report, Crawford, Anne. DPI library.

Level of review of results:

Internal peer review

Results:

Variation in soil C with time and management influence:

There was a general decrease of oxidisable organic carbon levels with depth in the soils measured. Pasture soils had a higher organic carbon level than cropping soils.

Site Trend over time (from July 97-Nov 98)
0-2.5cm 2.5-5cm 5-10cm 10-20cm
Ellinbank + None
Ellinbank + None
Ellinbank None + + None
Ellinbank
Strzelecki None None None
Loch None + None None
Nyora + None None
Mardan
Koonwarra None +
Tarwin Lower + +

Further detail provided in the report

Variation in soil pH with time and management influence:

In general, the soil pH decreased with depth. Soil pH responds to farm management and should be monitored on a regular basis to understand the influence of management practice.

Sampling detected a marked decline in pH with depth in ferrosols, whereas pH was more uniform in dermosols.

Site Trend over time (from July 97-Nov 98)
0-2.5cm 2.5-5cm 5-10cm 10-20cm
Ellinbank + + None
Ellinbank + + +
Ellinbank None + + +
Ellinbank +
Strzelecki + + +
Loch + None None None
Nyora None +
Mardan +
Koonwarra + + +
Tarwin Lower + + + +

Further detail provided in the report

Next steps

Soil indicators are a useful tool for land managers to monitor soil fertility over time. It is important that the indicators chosen are “fit for use” to be able to interpret according to the land use of the property.