Sandy soils cover a significant portion of Australia's cropping regions. These soils often have multiple constraints that limit their yield potential. Soil amelioration tillage practices have become widely adopted to address this, particularly in South Australia. Such practices aim to either alleviate physical constraints, including compaction or water repellence or, elevate clay from the subsoil to improve the fertility of sandy topsoils. These approaches have been rapidly adopted by growers due to the often-demonstrated yield increases and subsequent economic advantages of amelioration. Unfortunately, this is not a risk-free process, with significant soil testing and operator understanding required to correctly execute the amelioration techniques. Due to limited consideration for potential side effects and insufficient ground truthing and soil testing, this has resulted in areas of sandy soils which have become more constrained rather than improved. This is most commonly due to the elevation of large quantities of alkaline or sodic subsoil clay into the topsoil which has reduced soil fertility by increasing soil pH to a sub-optimal range for crop growth, damaging soil structure and reducing soil carbon.
The objective of this study was to address the negative effects of poorly executed high-rate clay spreading, which although has managed to address surface water repellence, has also caused a reduction in yield. Field trials were established at Wharminda on the Eyre Peninsula where highly calcareous clay had been broadcast spread at 300 – 400t/ha without incorporation, 20 years ago. In this project, a combination of different strategic tillage techniques were used and a selection of locally available amendments were applied pre-tillage to investigate the optimal methods for improving soil fertility at this site. Despite limiting rainfall conditions, it was found that tillage treatments that mixed the applied surface clay resulted in significant benefits to crop production.

This project aims to increase the adoption of Climate Smart Agriculture (CSA) interventions in the Australian horticultural industry, focusing on building soil organic matter (SOC) to improve drought resilience, productivity, and water use efficiency. Climate change, coupled with poor soils and limited adoption of sustainable practices, exacerbates challenges for horticultural growers, particularly in areas like the Northern Territory (NT). The project seeks to bridge the knowledge gap regarding the benefits of SOC and sustainable farming practices, providing growers with the tools to adapt to climate change. The project is organized into four key phases: Phase 1 (Benchmarking) assesses current horticultural systems and identifies relevant CSA practices; Phase 2 (Demonstrating) implements CSA practices at four field sites, focusing on building SOC; Phase 3 (Co-learning) engages stakeholders to identify key messages and promote CSA adoption; and Phase 4 (Incentivising) provides material incentives and technical support to encourage the uptake of CSA practices by growers. Key results include an increase in the knowledge and adoption of CSA practices, measurable improvements in soil organic matter at the demonstration sites, increase in crop production, and an increased capacity of growers to manage water resources effectively. The project contributes to improving soil health, reducing water usage, and enhancing climate resilience in the NT horticultural industry. The implications are far-reaching, as widespread adoption of CSA practices could foster more sustainable, resilient farming systems across Australia, supporting both agricultural productivity and climate change adaptation. Department of Agriculture and Fisheries of the Northern Territory Government acknowledges The Northern Hub for funding, and grower stakeholders in the NT for the wholesome support extended to this study.

The Kwongan ecosystem is a hotspot for plant biodiversity, harbouring many endemic and rare species, which are adapted to very low phosphorus (P) in soils. To cope, some plants exhibit different traits to enhance P acquisition, such as P-mining (exudation of carboxylates to mobilise P) and mycorrhizal symbiosis (symbiotic fungal partner intercepts and delivers P to the plant via hyphae). In some kwongan sandplains, surface mining has disturbed these ecosystems, requiring restoration and re-establishment of the native vegetation, often assisted by mineral fertilisation. By analysing floristic data of different post-mining restored sites (n = 103), we investigated if plant communities resemble that of native undisturbed kwongan (n = 52). As restored sites received different fertiliser applications (CropRich, SuperPhosphate, Apex low P or Non-fertilised), we were able to determine if P and nitrogen inputs affected the trajectory of P-mining and mycorrhizal plant species. Overall restored sites presented significant differences in vegetation composition compared to native communities. When analysing the effects of fertilisation on the vegetation after 10 years of development, we observed that P-mining species presented significantly higher cover (16%) in non-fertilised compared to fertilised sites (7-12%), mycorrhizal species were less affected by fertilisation (around 30%). On average, non-fertilised plots presented the highest richness of P-mining species (10 sp.) after a decade of restoration, while plots under CropRich had the lowest (6 sp.). Richness of mycorrhizal species was less affected by fertilisation. Considering all results (cover, richness and diversity), we show that soil fertilisation prior restoration has hindered the development of P-mining plants, which are not only adapted to low P, but may be sensitive to slightest increases in soil P. The fact that mycorrhizal plants were less affected show that these communities are shifting, being less favourable to the many endemic P-mining groups (e.g. Proteaceae, Haemodoraceae) found in Kwongan ecosystems.

Sandy soils pose challenges for crop production due to rapid water drainage, low nutrient retention, and susceptibility to erosion. This study examines nutrient distribution in the native veld and cultivated sandy soil near Darling (-33.284359 S, 18.350993 E) by analysing soil samples at depths of 0-5, 5-10, 10-15, 15-20, and 20-30 cm. The annual long-term in-season rainfall (April to September) is between 420 and 520 mm.
The native veld consists of the shrub, renosterbos (Elytropappus rhinocerotis), annual grasses, and bulbs, while cultivated fields follow a wheat-lupine-wheat-cover crop-canola rotation. Crops are planted with a tine or disc seeders with fertilisation (10 kg N, 14 kg P, and 12 kg K ha⁻¹)in the row, followed by additional nitrogen (50-60 kg ha⁻¹) based on rainfall. Strategic tillage is performed once every five years before canola if a compaction layer is detected.
Soil analysis revealed no significant differences in pH (all above 5). In cultivated fields, calcium and magnesium were significantly higher in the 0-5 cm layer and exceeded recommended levels (2 and 0.5 cmol kg⁻¹, respectively), but deeper layers showed deficiencies. Potassium levels did not differ significantly between native and cultivated soils, though only the 0-5 cm cultivated layer met the recommended 70 mg kg⁻¹ for cash crops. Phosphorus, sulfur, and boron were significantly higher in cultivated soil across all depths, while copper, zinc, and boron showed no significant differences. Although not significantly different, carbon content was higher in the 0-5 cm of cultivated soil (0.85%) compared to the native veld (0.34%).
The current management approach is sustainable, but calcium and magnesium deficiencies in deeper layers and severe sulfur deficiency in both soils indicate the need for corrective measures. Foliar application of micronutrients is recommended to optimise soil fertility and sustain productivity in this sandy soil system.

Western Australian (WA) sandy soils are known for their ironstone gravel content, which can affect soil properties such as porosity, water retention, and thermal capacity, influencing root development and plant growth. Studies have shown that gravel content can lead to reduced root development. The purpose of this study is to determine, under controlled conditions, how different gravel content levels impact the root developmental characteristics of wheat (cv. Scepter) in sandy soils of WA. We established wheat plants under different gravel levels, including a control (0%), 10%, 20%, 30%, 50%, and 70%, with five replicates per treatment and three plants per 6L square pot (240mm deep). Wheat plants were cultivated under natural light for 56 days during the 2024 winter season. During the study, plants were hand-watered with nutrient solution to sustain plant growth and maintain 60% water field capacity across treatments. Biomass production was recorded, and changes in root morphology in fresh-washed roots were recorded using a root scanner (Epson Perfection V850 Pro). Root images were analysed using the WinRHIZO™ PRO 2024a software. We identified a positive impact of low gravel on root development, whereas a negative impact from increasing gravel content was observed. Compared to the control and the rest of the gravel treatments, 10% gravel resulted in the highest mean value for total root length at 4,020±11 cm, root surface area at 364±60 cm2 and total root volume at 3±0.04 cm3. The no gravel treatment resulted in a low root length at 2,733±20 cm, with a surface area of 231±29 cm2 and a total root volume of 2.1±0.27 cm3. Gravel at moderate levels was beneficial to root development. Moderate gravel can make water and nutrients more accessible for plant uptake and contribute to soil fertility by storing available nutrients within the soil profile of Western Australian sandy soils.

There is growing interest in sustainable agricultural practices that reduce reliance on synthetic inputs and improve soil health. Plant biostimulants and bioamendments are increasingly recognised for their potential to enhance nutrient use efficiency, abiotic stress tolerance, and crop quality traits. Field trials were conducted from 2022 to 2024 on yellow deep sands and red deep sandy duplex soils at the Merredin Research Station to evaluate the effects of biostimulants and organic amendments on wheat performance. Biostimulants were applied as seed dressings or foliar sprays, and bioamendments were surface-applied. Inorganic fertilisers were applied alone or in combination with biostimulants or bioamendments at half, standard (district practice), and double district practice rates. The wheat variety Scepter was used in all trials. Untreated and unfertilised plots served as controls.

Commercially available products represented a range of biostimulant and bioamendment categories, including compost teas, manures, compost, biochar, humates, and microbial/mycorrhizal-based products. Their inclusion does not imply product endorsement.

Biostimulant effects varied across seasons. In 2022, no significant differences were observed in plant count, biomass, or yield. In 2023, grain yield differed significantly among treatments, with the highest yield from Bacstim applied with Ferticoat at double the district fertiliser rate, followed by Calibra Carbo at the same rate. Grain protein was also significantly higher in Calibra Carbo and Advance Promote treatments under high fertiliser input.

In 2024, biostimulants and organic amendments had no impact on biomass or yield. However, certain treatments significantly improved grain protein and microbial activity, with soil CO₂ release increasing by 21% compared to the control, suggesting positive effects on soil function.

The study highlights the variable responses to biostimulants and organic amendments, with potential benefits for grain quality and microbial activity in sandy soils under low-rainfall conditions. Further research is needed to assess their broader applicability.

Concerns about land degradation after clearing sandy upland terrain prompted this work. We used paired sites on the same soil and terrain. Satellite imagery and farmer interviews identified pairs that were cleared ~8 (CT1) and ~3 years ago (CT2). Farmers identified three soil types in undulating landscape based on experience, colour and production (but all contained, 80-81% sand). The six treatments (CT1, CT2 on 3 soils) had three replicates. Each replicate was sampled at 0-20 cm at 25 grid locations. The sand, clay and silt content of the three soils remained unchanged at CT1 and CT2. Soil organic C content was low. It decreased by 20% from 0.55 in CT2 to 0.44% in CT1. Soil pH in water remained virtually unchanged with values of 6.4-6.3 leading to high base saturations of 91-89% suggesting no soil acidification trend. With increasing number of years after clearing, ECEC values remained low at 1.1 and 1.0 cmol/kg, phosphorus buffering index decreased by 30% from 144-101, KCl-40 extractable sulphur (critical value (CV) of 4.0 mg/kg) was deficient at 2.6 mg S/kg in CT2 and became more deficient (2.3 mg S/kg) in CT1. Hot CaCl2 extractable boron (CV 0.12 mg/kg) decreased from borderline (0.12 mg/kg) to deficient (0.10 mg/kg), DTPA-Cu (CV 0.5-1.0 mg/kg) decreased from a deficient 0.47 to more deficient 0.43 mg/kg. There were small declines in exchangeable Mg, (0.59-0.57 cmol/kg) and DTPA Zn from 0.35- 0.32 mg/kg. DTPA Mn increased from 16.0-16.9 mg/kg. These soil changes occurred consistently among the three soils identified by farmers. These soil degradation issues (micro-nutrient deficiencies and low soil organic C) should be easily resolved using the right mix of inorganic and organic fertilisers in farming systems modified to sustain productivity and profits.