The work to optimise crop nutrition for drought resilience in Yorke Peninsula’s calcareous soils has encompassed two projects:
- Optimising nutrient input into low nutrient availability calcareous sands of southern YP: 2024-2025. Project lead: Northern Sustainable Soils. Project participant: Trengove Consulting
- Refining crop nutrition strategies for building drought resilience in highly calcareous soils in southern YP: 2026-2026. Project lead: Trengove Consulting
Optimising nutrient input into low nutrient availability calcareous sands of southern YP (2024-2025):
This project is part of the GRDC Riskwi$e program.
This project aims to determine best practice nutrient management strategies on low nutrient availability soils of SYP. These strategies will optimise financial returns and consider the risks and rewards, where soils with low inherent nutrient availability can require high fertiliser inputs and high costs. This project will enable growers to make better informed in season decisions and give them the tools to build drought resilience, and will build on the activities of the Central RiskWise project theme 2, expanding its reach to Southern Yorke Peninsula (SYP), which to date has had limited involvement with the RiskWise project. Outcomes from this project will be shared across the 5 farming systems groups involved with the Central ARG RiskWise project.
Refining crop nutrition strategies for building drought resilience in highly calcareous soils in southern YP (2026-2026):
Highly calcareous sandy soils across southern Yorke Peninsula present significant nutrient management challenges, with low phosphorus availability, poor nitrogen cycling and trace element deficiencies limiting crop productivity and increasing financial risk. Building on previous research, this project investigated practical nutrient management strategies to improve fertiliser efficiency, crop performance and profitability while strengthening drought resilience on these challenging soils.
Three replicated barley trials at Marion Bay evaluated phosphorus and manganese management, nutrient interactions and the performance of chicken litter compared with equivalent synthetic fertiliser programs. The findings provide growers and advisers with practical guidance on where nutrient inputs improve productivity and economic returns, and where additional fertiliser applications are unlikely to deliver value.
Project description:
Optimising nutrient input into low nutrient availability calcareous sands of southern YP (2024-2025):
This project was delivered near Marion Bay on the southern Yorke Peninsula, targeting a highly calcareous sandy loam with inherently low nutrient availability. A series of barley trials were established to evaluate best-practice nutrient management strategies aimed at improving crop production and supporting drought resilience in these challenging soil environments. Primary nutrient constraints investigated included phosphorus (P), manganese (Mn) and potassium (K), alongside the broader nutrient package of nitrogen (N), sulphur (S), zinc (Zn) and copper (Cu). The trials also assessed organic amendments and carbon coated minerals that have shown promise on comparable soil types elsewhere, helping to determine their suitability for local farming systems. The trials formed the foundation for extension activities, including a spring field site visit where treatment responses were observed and discussed with growers and advisers. Findings were compiled into a trial report and shared through industry channels, including Online Farm Trials, supporting knowledge transfer and informed nutrient management decisions across the region.
Refining crop nutrition strategies for building drought resilience in highly calcareous soils in southern YP (2026-2026):
Building on earlier SA Drought Hub and SAGIT research, this project further investigated nutrient constraints affecting highly calcareous sandy soils on southern Yorke Peninsula. Three replicated field trials at Marion Bay evaluated phosphorus and manganese fertiliser strategies, nutrient interactions and the performance of chicken litter compared with matched synthetic fertiliser programs.
Crop performance was monitored throughout the season using NDVI, tissue testing, biomass production, grain yield and grain quality assessments. The project also extended findings to growers and advisers through technical publications and local extension activities, supporting more informed fertiliser decisions that improve productivity while reducing unnecessary input costs and financial risk.
Key achievements and results:
Optimising nutrient input into low nutrient availability calcareous sands of southern YP (2024-2025):
Field trials conducted in 2024 investigated nutrient management strategies to improve crop production on highly calcareous sandy soils at Marion Bay. These soils are strongly alkaline, contain high levels of free lime and often present multiple constraints including poor nutrient availability and low biological activity. Four barley nutrition trials evaluated manganese, potassium and phosphorus fertiliser strategies, along with alternative nutrient sources such as chicken litter and biosolids. Crop assessments measured nutrient uptake, grain yield and quality, with economic analysis included where relevant to support practical decision-making.
Results demonstrated several opportunities to optimise fertiliser inputs. Large yield responses were observed from phosphorus applications (particularly liquid P), while no yield benefits were recorded from manganese or potassium treatments, indicating potential to reduce unnecessary inputs. Chicken litter outperformed synthetic fertilisers, delivering a 15% yield increase, whereas biochar and biosolids produced lower yields. While further seasons are required to confirm responses, the trials highlighted clear pathways for improving nutrient efficiency, adopting alternative fertiliser forms and strengthening drought-resilient cropping systems on calcareous soils.
Read the project technical report below.
Refining crop nutrition strategies for building drought resilience in highly calcareous soils in southern YP (2025-2026)- project update:
Building on previous research undertaken in 2024, this project refined nutrient management strategies for highly calcareous sandy soils on southern Yorke Peninsula. The trials improved understanding of phosphorus and manganese management, nutrient interactions and the role of chicken litter in crop production, providing growers with practical information to improve fertiliser efficiency while reducing unnecessary input costs and financial risk.
The project confirmed that nutrient responses on these challenging soils are highly specific, reinforcing the importance of matching fertiliser inputs to crop requirements and seasonal conditions rather than applying additional nutrients without clear evidence of benefit. The findings provide practical guidance for growers managing highly calcareous soils across southern Yorke Peninsula and other regions with similar soil constraints.
Key findings included:
- Moderate phosphorus application rates consistently improved early crop vigour and barley grain yield, while higher application rates provided little additional production benefit.
- Across two consecutive seasons of research, foliar manganese applications did not improve crop growth, biomass or grain yield, indicating manganese fertiliser applications are unlikely to provide an economic return under similar highly calcareous soil conditions.
- The previously observed interaction between phosphorus and manganese was not consistently expressed in 2025, suggesting this relationship is influenced by seasonal conditions and requires further investigation before broad management recommendations can be made.
- Chicken litter improved early crop vigour, however matched synthetic fertiliser programs supplying equivalent nitrogen, phosphorus, potassium and sulphur achieved similar biomass production, nutrient uptake and grain yield by the end of the season, demonstrating that nutrient supply rather than additional biological effects drove the response.
- Technical reports and trial summaries were produced to support grower and adviser decision-making, helping improve fertiliser efficiency and profitability on highly calcareous soils.
Read the project report below.
Further information:
Project Images
