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Helping Plants Thrive in Acidic Soils

Introduction

Around half of Australia’s agricultural soils are classified as acidic,¹²³ creating conditions that disrupt the biological processes responsible for nutrient cycling, root development and overall plant performance. When biology is compromised, so is productivity.

Independent trials conducted with NutriSoil to determine the optimal application rate for dryland wheat production found a clear yield increase when 5 L/ha was applied under acidic soil conditions.

To understand why this occurred, we need to zoom in on the rhizosphere, the microscopic zone around plant roots where biology, chemistry and physics collide. This blog unpacks the key biological mechanisms at play.

What is the Rhizosphere?

The rhizosphere is the narrow zone of soil (roughly 1 mm) directly influenced by plant roots. It is the most biologically active region in the soil, where plants, microbes and soil particles interact to exchange nutrients, water and biochemical signals. The physical, chemical and biological properties of the rhizosphere differ significantly from the bulk soil surrounding it.⁴

The Rhizosphere is where nutrient cycling happens. This is where stress responses begin. And this is where biological inputs like NutriSoil can have the greatest impact.

How Acidic Soils Impact Plants

Acidic soils interfere with the biological and chemical processes that underpin healthy plant growth. When soil pH drops, the ripple effects are significant:

Reduced availability of key nutrients such as phosphorus and molybdenum
Increased solubility of toxic elements like aluminium and manganese
Greater nitrogen losses, with nitrate easily leached from the root zone
Reduced habitat suitability for beneficial organisms, including nitrogen‑fixing bacteria, fungi and earthworms⁵

These constraints weaken plant resilience, limit nutrient uptake and reduce yield potential, unless biology is actively supported.

Phosphatase Enzymes: Unlocking Phosphorus

Phosphorus availability hinges on two critical enzymes: acid phosphatase and alkaline phosphatase.

Acid phosphatase is produced by plant roots and fungi
Alkaline phosphatase is produced by bacteria

Together, they break down organic phosphorus into inorganic phosphate — the form plants can absorb. This is essential because up to 80% of soil phosphorus can be locked up in organic forms.⁶

In the independent trial, both acid and alkaline phosphatase activity increased significantly where 5 L/ha of NutriSoil was applied at sowing. Higher enzyme activity means more phosphorus is being mineralised and delivered to the plant, supporting stronger growth and improved yield.

Stress Hormones in Plants

Plants constantly monitor their environment and respond to stress through hormone signalling. One of the most important stress hormones is abscisic acid (ABA).

ABA levels rise in response to:

drought
salinity
frost
heat
soil pH stress

One of ABA’s key functions is triggering stomatal closure, reducing water loss but also slowing photosynthesis. ABA also regulates germination, root development, seed maturation and reproductive processes.⁷

In the NutriSoil trials, ABA levels were lower in the treated plots. This indicates that plants experienced less stress, a strong sign that the rhizosphere environment had improved, even under acidic conditions.

A Real‑Life Example: The Haggertys’ Natural Intelligence Farming System

In the Western Australian Wheatbelt, Di and Ian Haggerty have spent more than two decades regenerating their wodgil soils (acidic, non‑wetting loams with high aluminium).

Their results speak for themselves:

nutrient‑dense grain in high demand
premium merino wool sought after by international designers
reduced fertiliser and chemical inputs
increased plant diversity
higher soil carbon and moisture retention

Biology is the engine of their system, and NutriSoil has been a key tool in their transition to what they call Natural Intelligence Farming. By building biological function, they’ve created a farming system that is more resilient, more productive and less vulnerable to environmental stress.

What About Alkaline Soils?

The independent study also found positive responses in alkaline soils:

Both acid and alkaline phosphatase activity increased
ABA levels decreased as NutriSoil application increased
Yield responses were observed, though higher rates were required

This means NutriSoil can improve biological function across a wide pH range, but additional nutrients (such as applied soluble phosphorus) will be needed as support in these conditions.

Take‑Home Messages

Plants growing in stressful environments divert energy into survival rather than production. As climate and market pressures intensify, building farming systems that are more efficient, biologically driven and more self‑reliant is becoming essential.

Some wholistic farming systems will be self-reliant, requiring minimal nutrient application if any with a systems and biological approach. Other systems will require more support including things such as nutrient application or mechanical means in addition to biology.

NutriSoil isn’t a silver bullet, but it is one of the most cost‑effective and practical ways to begin to unlock soil constraints and support biological function.

Applying NutriSoil at 5 L per tonne of seed, or 5 L/ha in‑furrow at sowing, is a simple, low‑cost strategy to increase plant tolerance to stress and improve nutrient availability, especially in acidic soils.

References

Tags:

*regenerativefarming #ag #agriculture #agriculturericulutre #amino acids #carbonfarming #farmers #fertiliser #healthysoilsystems #NuriSoil #pest #plants #suppression #sustainability #vermicast #wormjuice soil

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Helping Plants Thrive in Acidic Soils