NGN Managing and mitigating dry saline soils (magnesia patches) in South Australia

Dry saline soils affect large areas of South Australia’s cropping land. Previous data indicates that 6.5 million hectares of cropping land are affected by transient salinity or dry saline land. This is salinity not associated with a rising water table bringing salts to the surface. Rather, dry saline land is caused by evaporation and ‘wicking’ or capillary rise of water through the soil profile bringing salt to the surface (Department of Environment, Water and Natural Resources, 2016). The concentration of salts in the topsoil can also affect germination of sensitive crop types. The poor crop growth and cover of the soil as a result can see further evaporation and more salt drawn to the surface.

Anecdotally, there are concerns that these areas are increasing across the landscape and affecting crop establishment and growth. This is particularly through the Upper Eyre Peninsula, Mid and Upper North and parts of the Mallee. Seasonal changes in the amount of rainfall received and evaporation, as well as reduced groundcover coming out of drought conditions can make these areas worse in a paddock and take an extended amount of time to ameliorate.

A survey on the amount of dry saline land was conducted by Insight Extension for Agriculture and collected responses from growers across the Eyre Peninsula and Mallee in South Australia. This survey found that dry saline land is an increasing source of concern in these regions and across all respondents was responsible for an estimated $5 million in losses a year over the last 10 years. Growers responding to the survey also identified a lack of knowledge on where to find information to manage dry saline soils and what will work best for their landscapes (McDonough & Scholz, 2021).

To address these challenges, GRDC is investing in demonstration and extension of identification, management and amelioration of dry saline land. GRDC is seeking a service provider to deliver a program of work to address the challenges of dry saline land and support growers in identifying, managing and ameliorating these soils. This investment will achieve this through:

1. Codesigned trials of current known management and amelioration strategies to manage dry saline soils, including short term management (salinity tolerant crop types, opportunistic sowing activities or on-row sowing) or longer-term amelioration (mineral mulches, straw or organic matter spreading or gypsum applications)

2. Extension and communication activities to support adoption of the strategies identified, including supporting growers in the identification of the saline challenge on their properties. Extension will also leverage existing sources of extension materials and support their use and circulation.

This investment is designed to facilitate peer-to-peer learning groups in the identification of dry saline soils on their properties, and to inform decision-making regarding appropriate management or mitigation strategies through the utilisation of an established Field Diagnosis Workflow. These peer-to-peer groups will be based on the Upper Eyre Peninsula (Wirrulla, Kimba) and Mid and Upper North of South Australia (Eudunda, Warnertown, Balaklava/Owen) and will have different focuses depending on what has been previously demonstrated.