Addressing Salt, Sodium and pH

Contact:

Malmo Street Maffra

PO Box 727

Maffra – Vic – 3860

ABN: 88 065 838 078

Phone: 1300 094 262

E: maffralandcareoffice@gmail.com

Web: www.landcarevic.net.au

Context:

In 2010, the West Gippsland Catchment Management Authority commenced a project titled; Healthy Soils Sustainable Farms – building carbon and managing pH in West Gippsland. The project has been supported by the three years of funding from the Australian Government‘s Caring for our Country program with the five Landcare Network’s that operate within the West Gippsland region engaged to deliver soil health information to their respective communities. As part of the project delivery approach, the Maffra and District Landcare Network instigated a series of farmer workshops focussed around the basics of soil health management and production related issues. Based on a group learning model, the establishment of paddock demonstration sites was identified as being a critical learning component to assist farmers in following up on their theory based workshop learning. More importantly, it was recognised that conducting on farm demonstrations would provide the most effective way of positioning those farmers involved in the project with the best information to make realistic on farm management decisions and to adopt new soil management techniques relevant to their own farm enterprises. This case study provides some background to the property ‘Rathlyn’ one of the three properties in the Maffra and District Landcare area where a paddock focussed demonstration site has been established. The case study outlines the soil and pasture constraints identified within the focus paddock on ‘Rathlyn’ and provides a summary of the remedial techniques that are now being tested and trialled. Consideration of the treatments undertaken during the first year of the demonstration and the related observations are also provided. It is envisaged that this on farm demonstration site story will be updated as the various treatments and their results continue

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Project details

Objectives:

Based on the paddocks identified constraints, the purpose of the demonstration site at ‘Rathlyn’ and the various treatments chosen have been undertaken to test, observe and make considerations to the on farm managementactions that should;

  • Improve soil conditions by reducing soil acidity,
    sodicity and reduce the level of total soluble salts.
  • Break up soil crusting
  • Encourage preferred perennial grass species
    establishment and growth
  •  Reduce the % of saline related species in the pasture
  •  Encourage more vigorous and deeper plant root
    growth
  • Increase soil carbon levels

Location details

‘Rathlyn’ is located at the confluence of the Latrobe and Thomson rivers near the township of Sale. The current custodians of ‘Rathlyn’ are the 3rd generation of the same family to manage the 900 acre property.

Originally purchased by the family in the mid 1930’s, the property is comprised of 400 acres of improved pastures with a further 500 acres of low lying wetland morass used for opportunistic grazing when seasonal conditions allow.

‘Rathlyn’ is operated as a beef breeding property based on a Poll Hereford female herd. Herd numbers fluctuate based on seasonal conditions with 250 females being about the average carrying capacity of the breeding herd.

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The standard grazing regime followed on ‘Rathlyn’ is based on a 2 day grazing duration with a 3 – 4 week rest period (seasonal conditions being taken into consideration).

Beefcheque grazing principles are followed.

Grazing pressure is managed through the properties 30 odd rotationally based paddocks by 2-3 grouped mobs.

Rainfall at ‘Rathlyn’ nominally averages 550mm per annum but consistent with East Gippsland’s rainfall pattern, the predictability of rainfall is inconsistent.

The soil characteristics of ‘Rathlyn’ and in particular the 5ha demonstration paddock can be described as being heavy clay loam with acid, salt, sodic and sulphate characteristics.

Paddock history:

The demonstration paddock was cultivated and sown down to improved pastures in the 1960’s and in more recent years direct drilling has also occurred. The most recent pasture renovation taking place around 3 years ago. The paddock was split up into 4 smaller paddocks around 12 years ago and has been grazed under the properties standard rotation since this time.

The paddock has been known to be acidic and lime has been applied historically. The most recent applications of lime has been in the last few years with two applications of 2t/ha.

Pasture species recorded within the paddock at commencement of the demonstration included Cocksfoot, Ryegrass, Phalaris, Sub Clovers, Couch and a high percentage of Bucks Horn

Management considerations:

  • The strategic use of a higher application of lime should improve soil chemistry to create a more desirable growing environment for plants.
  • Extending the duration between grazing rotations should encourage preferred perennial grass populations to recover from grazing stress and aid more vigorous & deeper plant root growth.
  • Pasture cropping should assist to break up soil capping and crusting and help to open up the soil profile.
  • Increasing the grazing intensity should encourage less selective grazing whilst increasing the “herd effect” to provide more desirable growing conditions for preferred perennial plant species to survive and thrive.
  • The combination of above actions would collectively help to improve soil chemistry, improve pasture quality and vigour and increase pH and soil carbon levels

Year 1– observations and results

The character of ground cover for both the control and
treatment area changed significantly over the 10 month period
largely attributed to the well below average rainfall
experienced.
Looking at the control results first, winter grass species
dropped significantly from 23.8 % to 16.9%, while summer
grass species dropped from 8.8% to 5.3% with legumes
effectively disappearing.
A substantial decrease in broadleaf plants from 55.6% to
33.5% was also noted. These changes were offset by the
increases in bare ground (from 2.5% to 19.4%) and the
substantial increase in mulch from 5% to 25% explained in
part by green foliage converting to mulch due to the drought
like conditions and consistent grazing.

Looking at the control results first, winter grass species
dropped significantly from 23.8 % to 16.9%, while summer
grass species dropped from 8.8% to 5.3% with legumes
effectively disappearing. A substantial decrease in
broadleaf plants from 55.6% to 33.5% was also noted.
These changes were offset by the increases in bare ground
(from 2.5% to 19.4%) and the substantial increase in mulch
from 5% to 25% explained in part by green foliage
converting to mulch due to the dry conditions experienced
and consistent grazing.
The results of the treatment area also shows a decline in
winter grasses (41.9% to 21.8%) and summer grasses
(24.5% to 19.9%). Legumes declined from 6.3% to 0%.
Unlike the control, the level of broadleaf plants increased
from 21.1% to 37.4%. This means the treatment area
retained more active plant material (79.1%) compared to
the controls 55.7%.
The % of bare ground only increased by 2.4% which is
substantially better than the control demonstrating that
improvements in the treatment area were supported by the
assessments.
The initial 4.5 month rest period that the treatment area
experienced prior to being grazed did result in significant
dry matter differences in comparison to the control and
anecdotally, the recovery of the treatment area was also
substantially more vigorous than the control. (Considered to
be as a result of plant root reserves becoming better
established during the extended rest period).

Summary

At this stage the results of the demonstration overall provide
no real concrete support for the demonstration objectives
but ground cover improvements in the treatment area is
noteworthy particularly in regards to bare ground % and
active plant cover.
The lime application has not had a clear effect on calcium
levels at this stage but no negative consequences to
pasture performance has been noted

Soil and production constraints

As part of the healthy soils project, each participating farm identified what they considered to be their ‘worst’ paddock in terms of soil health and production constraints. A 5.0ha paddock situated adjacent to the Thomson river was selected on ‘Rathlyn’ as a result of the following attributes:

  •  Slightly acidic
  • Saline with high levels of total soluble salts
  • Sodic due to high levels of sodium
  • High in sulphate
  • Poor plant vigour and shallow root growth
  • Soil surface capping
  • High % of salt indicator species
  • Minimal organic matter

Applied treatments and management actions:

Demonstration plots were established on ‘Rathlyn’ within the selected 5ha paddock on the 22th May 2012.

To develop baseline evidence, transect quadrat assessments were recorded and soil samples taken for independently laboratory testing.

On the 10th July 2012, Lime (Buchan Ag Lime) was broadcast on the treatment area at a rate of 6t/ha.

On the 11th October 2012, the treatment area was heavily grazed with 150 cows and 150 calves. The grazing duration was 2 days.

The remainder of the paddock including the control area continues to be grazed according to the properties standard practice which was at the time involved exposing a pasture to grazing for a 2 day period followed by and average rest period of 3-4 weeks.

This continued until mid December 2012 when all stock were removed from the area. Therefore, control and treatment areas were left to recover.

On the 18th March 2013, transect quadrate assessments were recorded and soil samples were again collected for comparison.