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
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