Salinity Management ‘Warrigal Creek’ SaltCAP site

Introduction

Year of study: 2005 to 2016

Location: Warrigal Creek, Darriman

Farm size: 1,400 ha

Farm type: grazing, cropping, beef and sheep

Soil type: Mainly texture contrast soils (chromosols) and sodosols in discharge areas

Average annual rainfall: 580mm

Elevation: 0-26 meters

SaltCAP is focused on first understanding the principals that govern saline land capability, to then make the best decisions for which plants will work in the saline landscape for greatest production and financial gain.

The objectives are to effectively manage the SaltCAP site to:

  • maintain soil and nutrients on-site and reduce the opportunity for loss of fertility and decline in soil structure
  • maintain or increase productivity throughout grazing area.

Project details

The Warrigal Creek SaltCAP site was first set up in 2005 with support from the Yarram Salinity Group in order to demonstrate the use and assess the viability of a range of potential pasture species on saline land. Sustainable Grazing on Saline Lands (SGSL), trial plots were sown using tall fescue and tall wheatgrass.

The SGSL program aimed to support sheep producers (meat and wool) to profitably manage dryland salinity on their farms. SGSL was a national program initiated and funded by Australian Wool Innovation, Meat and Livestock Australia and the Federal Government’s Land Water and Wool agency. The project was co-funded, administered and delivered in Victoria by the Department of Primary Industry in conjunction with the CRC Salinity and CSIRO.

The site was originally planted with a range of recommended salt-tolerant species. From 2005 to 2011 measurements were taken on a regular basis of the following:
• DSE grazing days
• Kg Dry matter consumed
• Plant counts per individual species per plot.

Results

The results from the SGSL site monitoring were fairly inconclusive with no site treatment being recognised as being statistically significant in terms of extra growth.

In 2009, following a formal weed risk assessment carried out by the Future Farm Industries CRC and DPI, it was decided to remove tall wheatgrass from the trial area and to identify a less invasive pasture species suitable for the site.

A groundwater observation bore located approximately 650m from the SaltCAP site has been monitored on an intermittent basis over the last 15 years. Over the past few years the depth to groundwater has fluctuated from 3.5 to less than 0.8metres. The EC of the groundwater has been recorded in the range of 1000 to 9300 micro-seimens /cm (sea water is approx. 50,000).

A further piezometer is located within the SaltCAP site itself, recent sampling have indicated depth to ground water levels of around 0.6 to 1.0 metre with ECs around 4000.

Discussing options for future management on the Warrigal Creek site
Aerial photo of Warrgial Creek SaltCAP site

Figure 1: Warrigal Creek, location of the SaltCAP sites

This site is in close proximity to Jack Smith Lake, a State Game Reserve managed by Parks Victoria.

Plot picture Warrigul Creek
Sowing rates

Hydrograph and EC graphs of groundwater monitoring bore located in the vicinity of the site.

Hydrograph of groundwater monitoring bore

Graph showing fluctuations in groundwater over a 12 year period.

SaltCAP site informaton

In 2015 Nick Dudley (DEDJTR) and Sam Monks (Yarram Yarram Landcare Network) pulled together historical information and some new data to prepare this report.

Site area: 0.65 hectares, Slope: 0%-2%, Discharge area: 30-40 hectares

Present groundcover: Soil tolerant species. Pasture grasses interspersed with improved pasture species including Tall Fescue Ryegrass on elevated parts, trial site sown down to Puccinellia.

Estuarine wetland – Native Vegetation Cover: 3% (coastal saltmarsh)

Puccinellia Sown 2012

Typical vegetative cover on SaltCAP site

Typical vegetative cover on SaltCAP site – Nov 2014

Remnant Tall Wheat Grass

Typical vegetative cover on SaltCAP site – June 2015

Remnant Tall Wheat Grass growing in shelterbelt following extensive eradication program.

Remnant Tall Wheat Grass growing in shelterbelt following extensive eradication program

Percentage ground cover: 60-85% varies seasonally. Soil type: Sodosol (texture contrast soil with high level of sodium).

Structure: Moderately pedal easily fragmented. Texture: Sandy loam to sandy clay loam overlying heavy clay.

One metre soil core

One metre soil core taken at site showing highly layered profile (Nov 2014)

Compaction: Moderate despite the easily compactible nature of the soil, controlled grazing on site has prevented loss of groundcover and subsequent soil structure impacts.

Comparing pH in the soil

Soil Classification: Salinity Class 3 to 4

Highly saline, very few pasture species will grow, salt tolerant species only susceptible to sheet erosion and compaction when grazed under a set stocking regime. Crash grazing, or exclusion from grazing normally recommended.

In 2013, Lisa Warn from the McKinnon Project, University of Melbourne conducted soil tests in the trial paddock and a control paddock located 150 metre to the north.

The results confirm the saline nature of the soil with the EC being significantly higher than recommended.

Soil test recommendations:

Comments: Copper and zinc are high and not required in either paddock.

Usually need to apply molybdenum every 6-7 years – check when moly was last applied.

Note: Applying lime will make moly more available. Don’t apply molybdenum if applying high rates of lime to a paddock.

Note: Maintenance fertiliser rate will depend on stocking rate – eg: if stocking rate is 12 DSE/ha, you need 7kg/ha phosphorus per year (equivalent to 80 kg/ha single superphosphate).

SaltCAP Trial:

  • Salinity level (EC) and sodium % are both very high. Requires gypsum prior to pasture establishment to reduce sodium levels
  • Phosphorus and sulphur levels are very high – most likely due to poor drainage/high water-table
  • Potash is not required
  • You have the option to use high analysis P fertilisers (eg: double super, DAP) with low S contents as the soil sulphur level is so high
  • Autumn 2013: Apply gypsum at 2.5 t/ha prior to pasture establishment. Ay sowing: drill seed with 50 kg/ha DAP.

SaltCAP Control:

  • Salinity level (EC) and sodium % are both very high. Requires gypsum prior to pasture establishment to reduce sodium levels. However, as part of the SaltCAP project this paddock is being left as it is and is not planned to be renovated
  • Phosphorus is around the target level. You only require maintenance P fertiliser if there are responsive species present
  • Potassium and sulphur levels are very high – most likely due to poor drainage/high water table
  • Potash is not required
  • Option to use high analysis P fertilisers (eg: double super, DAP) with low S contents as the soil sulphur level is so high.
Botanical Composition 2015

Recommendations:

Puccinellia appears to be the best productive pasture-based option for the site. Given this, it is recommended that we investigate the options for encouraging the growth of Puccinellia including determining best grazing options (timing, seasonal approach, leaf stage and length of time in paddock) and fertiliser application. Whilst this is being considered we believe the best option is not to continue with current practice of applying the normal fertiliser regime of 3:1 annually at the rate of 150kg/ha. Lisa Warn (pers. comm.) has suggested that this is not appropriate for this saline area. The K & S levels are very high (because of high water table/poor drainage) so they shouldn’t be applying more K (in potash) & S (in the single super).

From the soil test taken before the site was sown, the agronomist recommended double or triple super (has P & not much S) as maintenance fertiliser and alternatively DAP (P & N, not much S) could be applied.

SaltCAP monitoring sheet
Local EVCs
SEMP plan

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The Healthy Soils Sustainable Farms project is supported by the West Gippsland Catchment Management Authority through funding from the Australian Government’s National Landcare Programme.

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