Where to start with addressing salty land

Best-practice management of salinity on your farm will improve productivity and prevent further degradation of the land. This article dives into the latest practical tips for best-practice saline land management, salinity risk identification and the latest decision-support tools to help with managing saline land in your enterprise.

Naturally occurring, salty areas on farms support native, salt-tolerant plants. These areas are classed as primary saline wetlands and should be encouraged. However, salty areas that develop due to rising groundwater tables are known as secondary saline sites and these require management to reduce impacts on land health and plant production. A 2002 survey by the Australian Bureau of Statistics showed that 51% of farms in Western Australia had areas with signs of salinity, representing over 1.2 million hectares.

Dryland salinity in Australia has mainly been caused by replacing deep-rooted, native perennial vegetation with shallow-rooted, annual crops and pastures that use less water. A 1,000-hectare farm receiving 500 mm of rainfall has 5,000 megalitres of water to manage yearly.

Excess water not used by plants and moving downwards past the root zone is called leakage. Leakage that drains below the root zone and reaches the saturated zone is called recharge and causes the water table to rise. This may cause saline groundwater to be brought up towards and eventually into the root zone somewhere ‘down-slope’, often called discharge. Discharge occurs as seepage, springs and base flow to streams, allowing evaporation or evapotranspiration of groundwater. Sufficient salt in the root zone can restrict or stop plant growth. Having mainly annual plants means that less water is used and there is potentially more deep drainage which contributes to rising groundwater tables. However, some deep drainage is needed to supply water to streams and wetlands.

Source: NSW Department of Primary Industries (original source Slinger & Tenison (2007))

Best-practice management of salinity aims to reduce recharge and then manage the saline areas to improve productivity and prevent further degradation of the environment. An integrated approach to managing water in your given landscape is required because the amount of leakage to the groundwater system and the manifestation of salinity depends on several factors related to the groundwater processes in the region, soils, geology, vegetation and climate.

What is your risk?

Early detection of saline areas makes rehabilitation much easier.

Assessing perennial species in your pastures and the rate of salinity can help assess the risk of salinity to your enterprise.

The establishment and persistence of perennial species in your pastures can be assessed by counting the number of perennial grasses per square metre.

To measure plants/m², make up a quadrat (metal square) with the dimensions of 25 cm x 25 cm
Throw the quadrat 20 times across the paddock and record the number of perennial plants inside the quadrat
Work out the average number of plants recorded inside the quadrat
Multiply the results by 16 to convert to plants/m²

Pastures will recover with careful grazing management if you have 5-8 perennial plants/m². Tool 7.5 on the Making More From Sheep website will help you choose the most appropriate grazing management strategy for your pasture.

Rate the level of salinity across your paddocks using tool 5.1, in combination with the use of tool 5.11 to identify indicator species.

You can also rate the level of salinity by testing your soil. Soil salinity is measured using electrical conductivity. You can assess this yourself if you have an electrical conductivity meter or an electromagnetic induction meter. Find more information about these methods here. Alternatively, you can have your soil salinity tested by a laboratory.

Management options

Best-practice for saline land includes:

Identifying the extent of the problem:

Saline areas are often not identified, especially in their early stages when more severe symptoms (i.e. bare scalds with white crystals on the surface) have not yet appeared
Key indicators of saline sites include:

They tend to be wetter than the rest of the paddock
Salt-tolerant plant species will become more common, such as sea barley grass
Soil colour often changes, usually getting darker
The areas will be preferentially grazed by sheep

Grazing management and fencing of saline areas:

Plants growing in saline soils may face the combined challenge of high salt levels, waterlogging that exacerbates the salinity impact and extreme grazing pressure, because sheep have a strong preference for grazing salty areas. This makes them vulnerable to overgrazing and erosion. Fencing and careful management of affected areas are required to maintain pasture cover

Establishing salt-tolerant species for grazing, depending on the productive capability of the saline area and economic return:

Identifying the salt-tolerant species that have colonised the saline site is a critical component of determining the productive capability, along with measuring the salinity of the soil. Options for salt-tolerant species that suit your enterprise can be identified using the Saltland Genie Web App. These webpages also provide some options for salt-tolerant plants: EverGraze, DPIRD - pasture legumes and grasses, saltbushes, trees and shrubs and perennial pastures. These options are not exhaustive

Establishing salt-tolerant trees and shrubs in saline areas that are not suitable for grazing or are too small to warrant the establishment of salt-tolerant species for grazing: Non-grazing options can be the best option in any situation and these areas contribute to the farm’s vegetation, biodiversity and visual appeal.

Seeking local advice from your neighbours, regional National Resource Management Authority, agronomist or the Department of Primary Industries and Regional Development is recommended because the signs of salinity and best management options vary depending on your region. This is particularly important if you plan to establish salt-tolerant species in your salty area/s as there is a higher risk of failure of plant establishment in saline areas compared to non-saline paddocks.

The Saltland Genie Web App, developed by Gillamii Centre with support from DPIRD, provides decision-support tools and resources for managing saline land in your enterprise.

DPIRD have provided an extensive list of case studies of Western Australian farmers and land managers that demonstrate their experience and learnings from managing dryland salinity. The case studies can be found here.

DPIRD have also produced an interactive map for the south-western agricultural region to share groundwater information collected over the past 30 years. Data available from the map can be used to inform your land management decisions. Find it here.

Where to find more information: