Selecting and managing salt-tolerant grasses

• Build on previous screening work undertaken by the department (project TU02005) and identify salt-tolerance in a wide range of turf grass species and cultivars.
• Trial the best performing cultivars in amenity areas to establish tolerance to wear and shade.
• Define best management practices for the sustainable growth of turf grass in salt-affected soil, in the areas of salinity monitoring, establishment, decompaction of soil and soil fertility.
• Demonstrate the validity of this study by working with a local municipality in selecting appropriate cultivars and cultural practices to establish and maintain healthy grass cover in a salt-affected amenity area.

• Turf cultivars are being grown hydroponically at six different salinities and shoot production is measured fortnightly along with final shoot and root mass, to ascertain growth response, as a representation of salinity tolerance. Each hydroponically grown cultivar is rated for leaf firing for each salinity level.
• Root mass fluctuations over time are determined for salt-tolerant grasses in replicated trials in coastal parkland, by taking core samples to a depth of 100 mm, in order to establish the effects of salinity, drought, wear, compaction and shade. Varying types of media are also being evaluated in this research.
• Two different soil cultivators, used at four working depths, have been used in a replicated and randomised study at salt-affected parkland, to investigate methods of decompaction in sodic soil. Assessment of this trial takes place by measuring soil hardness (using a Clegg hammer), penetration resistance (using a penetrometer), infiltration (using an infiltrometer), soil bulk density and gravimetric moisture (using core samples).
• Experiments to study the technology available to measure soil salinity and turf grass establishment methods (sod, plugs, seeding and sprigging) will be initiated in the near future.
• Verification of salt-tolerant grass selection and maintenance protocols will be actioned through saline demonstration sites, in conjunction with the Gold Coast and Redland City Councils. The sustainability of outcomes will be measured by regular rating of demonstration sites for several aspects of turf grass quality.

This project built on the successful outcomes of project TU02005 by adding to the database of salt tolerance among warm season turf grass cultivars, through further hydroponic screening trials. Hydroponic screening trials focussed on new cultivars or cultivars that were not possible to cover in the time available under the previous project, including: 11 new cultivars of Paspalum vaginatum; 13 cultivars of Cynodon dactylon; 6 cultivars of Stenotaphrum secundatum; 1 accession of Cynodon transvaalensis; 12 Cynodon dactylon x transvaalensis hybrids; 2 cultivars of Sporobolus virginicus; 5 cultivars of Zoysia japonica; 1 cultivar of Z. macrantha, 1 common form of Z. tenuifolia and 1 Z. japonica x tenuifolia hybrid.

The relative salinity tolerance of different turf grasses is quantified in terms of their growth response to increasing levels of salinity, often defined by the salt level that equates to a 50% reduction in shoot yield, or alternatively the threshold salinity.

The most salt tolerant species in these trials were Sporobolus virginicus and Paspalum vaginatum, consistent with earlier findings (TU02005: Loch, Poulter et al. 2006). Cynodon dactylon showed the largest range in threshold values with some cultivars highly sensitive to salt, while others were tolerant to levels approaching that of the more halophytic grasses. Coupled with the observational and anecdotal evidence of high drought tolerance, this species and other intermediately tolerant species provide options for site specific situations in which soil salinity is coupled with additional challenges such as shade and high traffic conditions.

See results of field testing.

• Dr Rachel Poulter, Research Scientist
• Bartley Bauer, Research Scientist

• Horticulture Australia Ltd

• the department
• Gold Coast City Council
• Redland City Council

• Redlands Research Station
• Beachfront parkland, Surfers Paradise
• Foreshore parkland, Birkdale

• Poulter R and Bauer B 2011, Establishment and Management of Salt-Tolerant Amenity Grasses to Reduce Urban Salinity Effects, Project Report TU 06006, Horticulture Australia Limited
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