Water quality is a critical factor that can make or break the success of your fertiliser applications on the farm. Whether you’re using organic fertilisers like compost, or synthetic options, the quality of your water can directly impact nutrient availability, soil health, and even the overall effectiveness of your fertilisers. For Australian farmers, dealing with varying water conditions—whether it’s salinity, pH imbalances, or contamination—can be challenging.
In this article, we’ll explore how poor water quality affects fertiliser performance, from the impact on soil pH to nutrient absorption and crop health. We’ll also provide practical organic solutions to help you manage water quality and optimise the effectiveness of your fertilisers, ensuring your crops and livestock thrive.
Water pH
For Aussie farmers, water quality is more than just a basic need—it’s key to the success of your fertiliser application.
The pH of your water directly impacts the nutrients available to your plants. Whether you’re using organic or synthetic fertilisers, the right water pH is key for making sure those nutrients actually get to where they’re needed.
How Poor Water Quality Affects Soil pH and Fertiliser Performance
If your irrigation water is too acidic or too alkaline, it can disrupt the soil’s pH balance.
Acidic water can reduce the availability of essential nutrients like phosphorus and calcium, while alkaline water can prevent plants from accessing vital minerals such as iron.
Fertilisers vary in their ability to withstand pH fluctuations, but poor water quality generally reduces their overall effectiveness, making it harder for plants to absorb nutrients properly.
Optimal pH for Plants
- Most plants thrive in slightly acidic to neutral conditions, with an optimal pH range between 6.0 and 7.0.
- pH 6.0 – 7.0: Ideal for most plants, including vegetables, fruits, and flowering plants. In this range, nutrients like nitrogen, phosphorus, potassium, and trace elements are most available.
- pH below 6.0: Water becomes more acidic, which can cause problems like toxic aluminium buildup in the soil and reduced nutrient availability. Plants may struggle to access key nutrients such as calcium, magnesium, and phosphorus.
- pH above 7.0: Alkaline water can reduce the solubility of nutrients like iron, manganese, and zinc, potentially causing nutrient deficiencies and stunted growth.
Impact of Water pH on Soil pH
Water pH can also directly affect soil pH over time. Consistently using water with a low (acidic) or high (alkaline) pH can gradually alter the soil’s pH, influencing nutrient availability in the long term. Monitoring both water and soil pH to ensure they stay within the ideal range can ensure optimal plant growth.
Managing Water pH
How to Test Soil and Water pH
It’s easy to test your water and soil pH with a simple kit or by sending samples off to the lab. Regular testing will help to keep track of any imbalances that could be affecting your fertiliser performance.
- Test water and soil pH: Regularly test both water and soil pH to ensure they are in the optimal range for nutrient uptake.
- Amend pH levels: If the pH is too low or too high, consider adding pH adjusters such as lime (for acidic water) or sulfur (for alkaline water).
- Water treatments: Use water treatment systems (such as pH neutralisers or filtration systems) to ensure water quality and improve fertiliser efficiency.
Water Quality and Dry Fertiliser Performance
For dry fertilisers, such as granular organic products or synthetic options, water quality plays a crucial role in ensuring that nutrients are effectively dissolved. Dry fertilisers rely on water to activate and move nutrients into the soil, where they can be absorbed by plant roots.
How Poor Water Quality Affects Dry Fertiliser Performance
When water quality is poor—whether it’s too salty, too acidic or alkaline, or contaminated—it can affect how well dry fertilisers dissolve and penetrate the soil.
Salty or contaminated water can bind to the nutrients in fertilisers, making them less available to plants. If the pH of the water is too high or low, certain nutrients in dry fertilisers can become insoluble or locked up in the soil, reducing the fertiliser’s effectiveness.
For organic fertilisers, such as chicken manure or pelletised compost, poor water quality can slow down microbial activity, which is crucial for breaking down nutrients into forms that plants can use.
How to Manage Water Quality for Dry Fertiliser Efficiency
To maximise the performance of dry fertilisers, use water that is balanced in pH and free from excess salts or contaminants.
Organic methods like composting and using organic mulches can help improve soil structure, ensuring nutrients from dry fertilisers are more readily available. Applying fertilisers when water conditions are ideal, such as just before, during or after rainfall, can also ensure better nutrient absorption.
Photo credit: Tow and Fert, Australia
Water Quality and Liquid Fertiliser Performance
Liquid fertilisers, whether organic or synthetic, rely on water to deliver them efficiently to plants. Good water quality ensures that these nutrients remain in a form that is accessible to plants.
Whether you’re using a liquid fish emulsion, biofertiliser or hydrolysate (organic) or a synthetic liquid nitrogen solution, water quality plays a significant role in the fertiliser’s effectiveness.
How Poor Water Quality Affects Liquid Fertiliser Performance
Poor water quality can impact both organic and synthetic liquid fertilisers in similar ways, although the specific effects may differ.
In the case of synthetic liquid fertilisers, which tend to be more stable, poor water quality can still hinder nutrient uptake by causing mineral salts to precipitate or creating imbalances that prevent plants from absorbing them.
For organic liquid fertilisers, poor water quality can disrupt the microbial processes that help break down and release nutrients. In particular, water that is too salty, acidic, or alkaline can affect the solubility of nutrients, reducing their availability for plant absorption.
Water with extreme pH levels can lead to nutrient lockout, where key minerals (like phosphorus or iron) become unavailable to plants. Excess salts can also place stress on plants, making it harder for them to absorb nutrients, regardless of whether they come from synthetic or organic fertilisers.
How to Manage Water Quality for Liquid Fertiliser Efficiency (Using Organic Methods)
To ensure the best performance from both organic and synthetic liquid fertilisers, it’s beneficial to use water with balanced pH and low salinity. Rainwater is often a good option, as it’s typically more neutral and free from contaminants.
For synthetic liquid fertilisers, careful monitoring of water pH and salinity is important, as even slight changes can impact their efficiency.
For organic liquid fertilisers, ensuring that the soil’s microbial health is supported is equally important.
Adding compost teas, worm castings or biologically activated fertilisers to the soil can help boost microbial activity and make organic liquid fertilisers work even better.
Timing your fertiliser applications to coincide with rain or during periods when water quality is optimal will also help maximise nutrient uptake by plants.
Water Quality and Biologically Activated Fertilisers
Biologically activated fertilisers, or biofertilisers such as SONIC Liquid Fish or SONIC Liquid Seaweed, are microbial inoculants containing living microbes that enhance soil health and provide plants with readily available nutrients.
Biofertilisers work by introducing and activating beneficial microorganisms in the soil, which help break down organic matter and unlock nutrients that plants can absorb. The quality of water used to apply biofertilisers plays a role in ensuring that these microbes remain viable and effective.
How Poor Water Quality Affects Biofertiliser Performance
For biologically activated fertilisers, the primary issue with water quality can be the pH level. These biofertilisers contain live organisms that are sensitive to extreme pH levels. If the water used for applying the fertiliser is too acidic (low pH) or too alkaline (high pH), it can harm the microbes.
- Low pH (acidic water) can stress or kill beneficial microbes, disrupting the biological activity and reducing the biofertilisers effectiveness.
- High pH (alkaline water) can similarly damage the microbes and some nutrients may become less soluble or more difficult for plants to access in highly alkaline conditions.
In addition to affecting the microbes in the biofertiliser, poor water quality can also influence the overall microbial ecosystem in the soil. A disruption in the microbial balance can limit the biofertiliser’s effectiveness, as the microbes need to interact with existing soil organisms to promote nutrient cycling and improve soil health.
How to Manage Water Quality for Biofertiliser Efficiency
To ensure the best performance from biologically activated fertilisers, use water with a neutral to slightly acidic pH—ideally between 6 and 7. This pH range is ideal for maintaining the health and activity of the beneficial microbes in the fertiliser.
Rainwater is often an excellent choice, as it is typically neutral to slightly acidic and generally free from harmful contaminants. If your water source has a pH that is too high or too low, consider adjusting it naturally by using organic amendments like dolomite lime (to raise pH) or elemental sulphur (to lower pH), bringing it closer to the optimal range.
How Biofertilisers Help Maintain Healthy Soil pH
Biofertilisers packed with beneficial microbes play a subtle but powerful role in keeping soil pH stable. These microbes work with the soil’s natural processes to create a balanced environment where plants can thrive. They do this by:
- Releasing gentle organic acids that help buffer soil chemistry rather than causing sharp shifts in pH.
- Speeding up the breakdown of organic matter, a process that naturally smooths out pH fluctuations.
- Strengthening the soil’s microbial ecosystem, ensuring diverse microbes can adapt to changes and maintain overall stability.
When biofertilisers are made with organic materials—like fish, seaweed kelp, or quality compost—they become even more effective. These additions feed the microbes, boost the soil’s cation exchange capacity, and help the soil resist sudden changes in pH, creating a more resilient growing environment.
Water Contamination and Fertiliser Ineffectiveness
Contaminants like pesticides, heavy metals, and excess salts in water can interfere with the nutrients in your fertilisers, especially organic ones. These pollutants can bind to the nutrients in your fertiliser, making them unavailable to your plants. Synthetic fertilisers aren’t immune either—contaminated water can still reduce their effectiveness.
How to Test Water for Contamination
Test your water at a lab for common pollutants such as heavy metals, pesticides, or other chemicals that may affect your fertilisers. A comprehensive water test will help pinpoint any potential problems.
How to Manage Contaminated Water
Use natural filtration systems, like sand or biofilters, to remove contaminants from water. Organic farming techniques like cover cropping and using biochar can help absorb and neutralise harmful substances in the soil, ensuring better fertiliser performance. Rainwater harvesting is another way to avoid contaminated water.
Chloride and Flouride in Water
In the book ‘Living Energies’ by Callum Coats, the write explains how “..chlorine eradicates all types of bacteria, beneficial and harmful alike..water that has been sterilised to death; in other words, a water-corpse”. He goes on to say “..it also disinfects the blood or sap (up to 90% water) and in doing so kills off or seriously weakens many of the immunity-enhancing micro-organisms.
This eventually impairs their (bacteria) immune systems to such a degree that they are no longer able to eject viruses, germs and cancer cells to which the respective host-bodies ultimately fall victim”.
Summary
In conclusion, water quality is a huge factor in how effective your fertilisers are. Whether you’re using organic products like compost or liquid fish hydrolysate, or synthetic fertilisers, poor water quality can limit nutrient availability and reduce the overall performance of your fertilisers.
By regularly testing your water, using organic methods to manage pH and contaminants, and harvesting rainwater, you can maximise fertiliser efficiency and keep your farm thriving.
Disclaimer:
The information in this article is for general guidance and not professional advice—always consider your individual circumstances or consult with a professional before making decisions. For more details, please review our full Disclaimer.
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