Farm productivity and resilience: How organic soil amendments repair soils and build resilience

Across Southeastern South Australia and Western Victoria, today’s growers face many challenges. There are intense rainfall events followed by longer dry spells, and ongoing pressure to keep soils productive year after year. In this context, soil amendments, including high-quality composts and blended compost formulations, are increasingly used to repair agricultural soils.

Organic amendments are not a quick fix or a guaranteed way to boost yields. Instead, they offer a practical, proven way to rebuild the foundations that underpin productivity and drought resilience.

Importantly, organic amendments don’t need to replace conventional programs. In fact, many of the best results are achieved when used in conjunction with traditional fertilisers. This approach combines targeted nutrient delivery with long-term improvements in soil health.

This article explains how soil amendments enhance farm productivity and drought resilience.

Productivity: repairing the drivers of consistent performance

Soil biology revival: feeding the nutrient cycling engine

Healthy soils are living systems. Soil amendments add carbon and organic matter that support soil microbes and soil food ecosystems. They can improve nutrient cycling, soil aggregation, and overall soil health over time. In practice, this helps crops and pastures access nutrients more efficiently and helps maintain more even nutrient levels. This is especially true where soils have been depleted or contain low organic matter.

Biology-led gains are usually time-dependent and influenced by soil type, rainfall, management, and amendment quality. So the primary goal of organic soil amendment is to improve the reliability and reduce the variability of nutrient cycling.

Soil structure and root growth: improving what roots can reach

A significant productivity constraint in many paddocks is not a lack of targeted nutrients but rather restricted root exploration caused by compaction, poor aggregation, crusting, or an unstable structure. Soil amendments are commonly associated with improved aggregation and soil structure. Microbes generate biological glues that help bind soil particles into more stable aggregates. A better structure supports pore space, aeration, and infiltration pathways, allowing roots to penetrate deeper and function more effectively.

Long-lasting nutrition: slow-release supply and better nutrient holding

Compost and blended organic amendments provide a wide range of nutrients, but their most significant value often lies in their ability to help soils hold and cycle nutrients. Soil organic matter influences nutrient retention (including cation exchange capacity), buffering and nutrient availability over time.

Compost provides gradual nutrient release while also improving soil structure and biology, supporting a strategic, long-term soil improvement program rather than acting as a quick fix.

Drought resilience: storing more moisture, capturing rainfall better, and protecting topsoil

Moisture-holding capacity: increasing plant-available water

Soils with higher organic matter tend to act more like a sponge, holding more water and releasing it more steadily to plants. Compost is often discussed as a means to enhance water-holding capacity, though outcomes depend on compost quality and its application.

Infiltration: getting rain into the soil profile

Organic amendments can enhance infiltration by supporting aggregation and pore continuity, thereby reducing sealing and runoff during heavy rainfall. Drought buffering begins with improved infiltration, which increases the likelihood that rainfall is retained as soil moisture rather than lost as runoff or evaporation.

Erosion control: keeping your most valuable asset where it belongs

Topsoil is where most of the biology, carbon, and nutrients are concentrated, so erosion is a direct hit to both productivity and resilience. Improved soil structure reduces the potential for erosion, while better groundcover and surface protection can reduce rainfall impact and runoff energy.

Soil amendments or traditional fertilisers? Both is often the answer

A common misconception is that growers must choose between soil amendments and synthetic fertiliser. Evidence increasingly frames the answer as both, because they do different jobs.

Traditional fertilisers are precise and fast for targeting specific nutrient gaps. At the same time, compost and soil amendments improve the soil’s physical and biological capacity to hold water and cycle nutrients - benefits that fertilisers can’t deliver on their own.

A practical way to think about it:

• Use synthetic fertilisers to target nutrient deficiencies.
• Use organic amendments to rebuild soil function (structure, biology, water dynamics), and apply slow-release maintenance nutrition, to make the nutrient program more efficient and resilient over time.

How soil amendments benefit South Australian soils

Agricultural soil profiles are often constrained by limited moisture-holding capacity and low nutrient retention, making them more sensitive to dry finishes and leaching. This inhibits productivity and reduces the land’s resilience to dry periods. Alternatively, they may have strong nutrient-holding potential but can be limited by compaction, poor infiltration, waterlogging risk, or structural instability.

Soil amendments bring many benefits to the productivity and resilience of the land across various soil and climate types, as well as to the crops and pastures grown in them.

• Biology revival: Organic inputs provide carbon that supports microbial activity and nutrient cycling in low-carbon sands.
• Nutrient efficiency: Integrating compost with fertiliser can improve nutrient retention and availability throughout the season.
• Longer-lasting nutrition: Organic matter can improve nutrient-holding capacity, helping reduce nutrient loss pathways and supporting steadier nutrient availability.
• Structure and trafficability: Organic matter can improve aggregation and pore space, supporting rooting, aeration, and workability.
• Root zone improvement: Compost contributes to aggregation and improved pore structure, which can support more effective rooting and nutrient interception. An improved structure can also reduce mechanical resistance, enabling deeper root exploration.
• Infiltration: Improved aggregation and surface condition help rainfall enter the soil rather than running off.
• Moisture retention: Compost is often used to improve moisture-holding capacity in drought-prone soils, particularly when applied consistently over time.
• Erosion control: Stable aggregates and protected surfaces reduce erosion risk during heavy rainfall and protect against wind erosion on exposed sandy surfaces.

Bio Gro soil amendments (what growers often choose)

• AgriGro (100% compost) is a vital base amendment that builds organic matter and soil function over time through gradual nutrient release and structure/biology benefits.
• AgriGro+ 30p (70% compost + 30% pig manure) adds processed pig manure to deliver controlled, rate-dependent nutrition, improving soil structure and fertility.
• AgriGro+ 30c (70% compost + 30% chook manure) adds chook manure to deliver fast, nitrogen-rich nutrition. It improves soil structure, microbial activity and crop performance.
• GroBalance (70% Compost + 30% Ag Lime) is an amendment formulation that combines high-quality compost and agricultural lime to correct soil pH and enhance nutrient availability in acidic soils.
• GroBooster (70% Compost + 30% Gypsum) adds gypsum to improve soil structure, aggregation, and chemical balance.
• AgriGro Custom (tailored compost-based formulation) is produced to order according to agronomic testing and analysis.

How Bio Gro helps

Bio Gro’s agricultural products and services are built around helping producers create healthier land for a better tomorrow. We call it: Soil First. Future Focused. In practical terms, our role for growers is defined by four key points:

Local support
Bio Gro works closely with producers and growers of all types across Southeastern South Australia and Central and Western Victoria. We’re a family-owned business that’s part of your local communities.

Quality and consistency
Bio Gro compost complies with Australian Standard AS4454, reflecting a focus on product safety, maturity and consistency, so growers know what they’re getting, season after season.

A fit-for-purpose agricultural product range
The soil amendment range includes AgriGro 100% compost and a range of amendment formulations developed to target specific soil improvement needs. AgriGro Custom provides formulations tailored to unique land and production requirements.

Service and support that make adoption easier
Bio Gro provides technical support to farmers and agronomists, including specialist agronomist support and ongoing product development based on real-world experience. Delivery and spreading services integrate organic amendments into existing farming systems without adding unnecessary operational burden.

Better soil function and more resilient farming results

Organic amendments are best viewed as a long-term soil management strategy to support productivity and resilience. They are used to rebuild soil biology, enhance structure, strengthen nutrient cycling, and help store rainfall as soil moisture. Outcomes depend on the rate, timing, and specific context.

The most practical approach is often organic amendments + targeted fertiliser, guided by soil testing and local agronomy.

Getting started

Start with the constraint that costs you the most, such as water retention on sands, infiltration or structure on clays, or surface protection where erosion and evaporation are high. We’ll help you and your trusted agronomist to develop a program that suits your rotation, budget, and logistics.

Contact Bio Gro today for information, advice or a free consultation with one of our specialist agronomists.

Sources:

• Australian Government Department of Climate Change, Energy, the Environment and Water
• Soil Health