Tactics to minimise frost damage on the Eyre Peninsula

Aiming to identify and demonstrate the most valuable and relevant frost mitigation tactics on the Eyre Peninsula, a GRDC-funded project was conducted during the 2022 and 2023 growing seasons. To address regional knowledge gaps and assist in disseminating information, a steering committee was formed, comprising advisors working with growers in frost-affected areas and local researchers.

Field trials were conducted from 2022 to 2023, encompassing strategies that were either commonly used in the area, showed promise in frost research from other regions, or were of interest to growers despite limited supporting literature. A summary of the frost tactics demonstrated to growers is provided below.

Varietal Phenology: This trial showcased various sowing time and variety combinations available to growers to avoid frost exposure. Extending this work over two contrasting growing seasons highlighted the complexity of making these decisions without reliable frost and rainfall forecasts. Multiple frost events, both early and late in the season, made it challenging to consistently choose a wheat variety and sowing time strategy that reduced frost risk without the benefit of hindsight. Barley consistently achieved higher yields across several phenology and sowing time combinations than wheat in frosty environments.

Crop Type: In 2022, a trial of different crop types demonstrated the varied reactions of crops like canola, beans, lentils, and vetch to frosty environments. Growers and advisors sought to understand the relative frost damage risk across a range of break crops, especially given the growing importance of these crops in the farming system and the decline in livestock production. The recent expansion of lentil cultivation across central and upper Eyre Peninsula necessitated more knowledge about frost impacts on lentils and the suitability of alternative break crops such as faba beans. The work conducted in 2022 found that lentils experienced more frost damage than faba beans.

Nutritional Amendments and Ice-Nucleating Bacteria Control Products: This trial aimed to assess the value of various products purported to improve crop resilience to frost damage. Claimed mechanisms included foliar transpiration inhibition, nutrition-based sugar enhancement, plant health enhancement, floret sterility reduction, and antibacterial properties. Over two years in high frost incidence environments, none of the products demonstrated a yield benefit beyond correcting well-documented nutritional deficiencies, such as low potassium levels in sandy soils.

Zoning: Frost damage consistently affects certain landscape areas due to topography and air movement. Consequently, some paddock areas incur significant frost damage, while nearby areas remain unaffected. With advancements in precision farming equipment, growers can now manage high frost risk areas differently. To evaluate the benefits of such management, phenology, crop type, and nutritional amendment trials were mirrored in both high and moderate frost risk zones within the same paddock. Data showed that high-risk zones experienced more severe frost damage, and strategies like sowing longer-season wheat varieties (winter varieties) and various barley varieties had higher value in high-risk zones. This demonstrated the value of managing zones differently. Collecting data over additional seasons will be crucial for modelling yields and frost damage accurately, aiding growers and advisors in making informed management decisions based on frost risk.

Soil Amelioration: Anecdotal evidence from growers and previous research in Western Australia suggested a potential relationship between soil amelioration on sandy soils and frost mitigation. Data and observations from eight sites over 2022 and 2023 allowed direct comparisons between ameliorated and original soil compositions. Six of the eight site comparisons found that soil amelioration occasionally reduced daily canopy temperature fluctuations, with temperature differences increasing as conditions became more extreme. Some events were up to a few degrees warmer during the coldest overnight periods. Instances where amelioration did not result in warmer temperatures were found on heavier textured soils. Understanding the underlying mechanisms may help quantify the soil-temperature interaction level needed to reduce frost damage.

Frost tactics final report June 2024