The effect of land management on the structure of intensively cropped soils in West Gippsland

Year of study

1987-89

Project ownership

Lead organisation & collaborators

Department of Agriculture National Soil Conservation Program

Contact:

Kathleen Hirst, Mark Imhof and Bruce Weston Environmental Sciences Unit State Chemistry Laboratory Department of Agriculture

Project details

Objectives

To investigate the impact of land management on intensively cropped krasnozem soils in West Gippsland.

The effects of wheel traffic, deep ripping and green manure crops on soil structure and soil hydrology were assessed.

Hypotheses/conceptual models

Variations in aggregate stability are related to organic carbon

Basis of trial

Traffic management and stability in soil is related to organic carbon.

Management practices tested

Green manuring, crop rotation.

Best available science assessment

Overall Score: 31

Overall rating: High

report-2-1

Interpretation

Summary of key messages/findings of trial

Aggregate stability of the soil varied within a paddock and was influenced by previous management – generally related to organic matter levels in the soil. On a continuously cropped paddock, green manure crops (alone) had no measureable effect on soil cloddiness, aggregate stability or organic matter levels.

What recommendations were made about soil/land management and soil health?

It is recommended that:

  • Wheel traffic be minimised
  • Wheel tracks and other compacted areas be ripped to decrease surface compaction, promote infiltration and minimise the potential for runoff and soil erosion
  • Organic matter should be maintained through the use of pasture rotations and green manure crops to sustain aggregate stability.

These options will decrease the potential for soil erosion and soil structural decline on West Gippsland’s high value cropping land.

Challenges/opportunities to apply trial results/findings

Not specified

Location and site details

Trial site details

1992
High rainfall (1100 – 1200mm)
Krasnozem soils. Undulating terrain, dissected by steep – sided valleys. Slope lengths typically 100 – 500m, angles in the range of 5 – 40%

Management history

Pre-trial management

Trial management

Not specified

Experimental design

Treatments

From post green manure crop 1987 to pre potato harvest 1989 aggregate stability and organic carbon levels were monitored for soils under oats, peas, tetilla ryegrass and the control.

Sampling strategy varied by site and land use status (i.e. what period of the crop rotation the land was in)

Trial design/layout

N/A

Soil sampling method

Soil sampling

Aggregate stability of individual clods was obtained from dry sieving and was assessed after green manure crops had been worked into the ground.

Production measurements

Plant and/or animal production measurements

Not specified

Cost and value of production

Not specified

Treatment results

Variation in soil C with time and management influence

Aggregate stability was found to be generally related to organic matter levels.

During the monitoring period both aggregate stability and organic carbon were fairly constant and there was little difference between the crops.

Variation in soil pH with time and management influence

Not specified

Other soil treatments

Untrafficked furrow treatments were found to have greater aggregate stability than other treatments.

Soil strength is significantly compacted by wheel traffic at the start of a season, but declines over the course of the growing season.

Variation in productivity/ profitability with time & management influence

N/A

Other measures of treatment response (e.g. water quality )

N/A

Reporting

How results have been reported (e.g. leaflet, technical report, journal article)

Technical Report Hirst, K. M. (Kathleen) (1992): The effect of land management on the structure of intensively cropped soils in West Gippsland , Department of Agriculture

How can a copy of any relevant reports be obtained?

DPI

Level of review of results

Internal Review

Miscellaneous

Intellectual property ownership

DPI

Approval to publish project summary in trial directory

Not required, report released publicly