If you’re looking to boost your farm’s productivity without breaking the bank, you’re in the right place. In this article, we’ll delve into seven time-tested, cost-effective, organic fertilisers that have been the backbone of sustainable farming for generations. From biochar and liquid fish to seaweed, rockphos, compost, and vermicast, these natural wonders are trusted by growers across Australia and world-wide.

Whether you’re a seasoned farmer or just starting out, these organic natural fertilisers will enrich your soil, improve plant health, and enhance your yields. Let’s dig in and explore how these tried-and-true products can transform your farm.

7 Time-Tested Natural Organic Fertilisers

seaweed fertiliser and mineral feed supplements for livestock

1. Organic Seaweed Kelp-Based Fertilisers – Full Spectrum Minerals

Seaweed Benefits

Kelp-based products are among the most versatile organic farming products available.

Seaweed is rich in essential micronutrients, which help enhance soil structure and stimulate plant growth

These natural organic fertilisers improve water retention in the soil, increase the availability of nutrients to plants, and support the development of beneficial soil microorganisms. As a result, crops grown with seaweed kelp fertilisers are often healthier and more resilient.

Organic Seaweed Fertiliser Uses

One of the standout features of seaweed kelp-based fertilisers is their versatility in organic farming. They can be used as:

  • Soil Conditioner: Enhances soil texture and fertility, promoting robust plant growth.
  • Foliar Spray: Provides immediate nutrient uptake through the leaves, boosting plant health and growth rates.
  • Compost Activator: Speeds up the composting process by adding essential nutrients and promoting microbial activity.

Application Tips

Integrating organic seaweed kelp fertilisers into various farming activities can maximise their benefits. Here are some best practices for applying these organic farming products:

  • Soil Application: Mix the kelp fertiliser into the soil at the time of planting or as a top dressing during the growing season. This ensures that the nutrients are available to the plants throughout their growth cycle.
  • Foliar Spray: Dilute the kelp extract according to the manufacturer’s instructions and apply it directly to the leaves using a sprayer. This method is particularly effective during periods of rapid growth or stress.
  • Compost Activation: Add seaweed kelp to your compost pile to boost its nutrient content and speed up decomposition. This enriched compost can then be used to enhance soil fertility across your farm.

Additional uses for seaweed include;

  • Livestock Feed Additive: When added to livestock feed, seaweed can help to improve digestion and nutrient absorption. It also has the potential to reduce methane emissions from livestock, contributing to more sustainable farming practices.  See probiotic liquid seaweed for livestock.

By incorporating seaweed kelp-based fertilisers into your farming practices, you can improve soil health, enhance plant growth, and support sustainable agricultural methods. These organic farming products offer a practical and effective solution for farmers looking to optimise their operations naturally.

fish hydrolysate fertiliser

2. Organic Fish-Based Fertilisers – Liquid Protein

Fish-based fertilisers, such as fish hydrolysate fertiliser, is a potent organic solution derived from whole fish, which has been broken down into a liquid form. This method preserves the essential nutrients and beneficial compounds, making liquid fish an excellent choice for organic farming.


Organic fish fertiliser is packed with essential nutrients, including nitrogen, phosphorus, and potassium, as well as trace minerals, amino acids, and fatty acids. These nutrients are vital for healthy plant growth and development.

  1. Promotes Microbial Activity: The organic matter in fish fertiliser supports the growth and activity of beneficial soil microorganisms. These microbes play a crucial role in nutrient cycling, breaking down organic matter, and enhancing soil fertility.
  2. Boosts Plant Health: Regular use of fish fertiliser can improve plant vigour, enhance root development, and increase resistance to pests and diseases. The nutrients and organic compounds provide plants with a balanced diet, promoting overall health.


  • Soil Drench: Applying fish hydrolysate as a soil drench delivers nutrients directly to the root zone. This method helps in improving soil structure, increasing microbial activity, and ensuring that plants have access to essential nutrients for growth.
  • Foliar Feeding: Foliar application involves spraying fish fertiliser directly onto the leaves of plants. This allows for quick nutrient absorption through the leaf surface, providing an immediate nutrient boost and enhancing photosynthesis.
  • Compost Enhancement: Adding fish hydrolysate to compost piles accelerates the decomposition process. The nutrients and organic compounds in the fertiliser feed composting microbes, resulting in a richer and more nutrient-dense compost.

Application Tips

  1. Dilution Ratios: Dilute organic fish fertiliser according to the specific needs of your plants and the manufacturer’s recommendations. A common dilution ratio is 1:50 (1 part fish hydrolysate to 50 parts water) for soil drenching and foliar feeding. Always check the label for precise instructions.
  2. Timing: Apply fish fertiliser during the early morning or late afternoon to avoid the heat of the day. This prevents rapid evaporation and allows for better absorption of nutrients by the plants. For foliar feeding, ensure the leaves are not wet from rain or irrigation to maximise uptake.
  3. Preventing Clogs: When using fish fertiliser in sprayers, regularly clean your equipment to ensure smooth application and consistent coverage.

Organic fish fertiliser is a versatile and powerful tool for organic farming, offering numerous benefits and applications.  For more detailed information and sourcing options, explore SONIC Natural Farming liquid fish products and affordable supply options.


3. Compost – A Powerful Organic Farming Ally


Compost and compost tea is a potent organic fertiliser, brimming with benefits that enhance the overall health and productivity of your farm. Here’s some of the attributes of compost tea:

  • Enhances Soil Microbial Life: Compost tea is rich in beneficial microorganisms such as bacteria, fungi, and protozoa. These microbes are crucial for maintaining a healthy soil ecosystem, aiding in the breakdown of organic matter and nutrient cycling.
  • Improves Nutrient Uptake: The microorganisms in compost tea help in breaking down nutrients into forms that plants can easily absorb. This improves the efficiency of nutrient uptake, ensuring that your plants get the essential nutrients they need for robust growth.
  • Builds Disease Resistance: Regular application of compost tea can enhance plants’ resistance to diseases. The beneficial microbes compete with pathogenic organisms, reducing the incidence of plant diseases and promoting healthier crops.


Compost tea is versatile and can be applied in several ways to maximise its benefits:

  • Soil Drench: This method involves applying compost tea directly to the soil around the base of the plants. It helps in improving soil structure, enhancing microbial activity, and ensuring that the roots have access to vital nutrients.
  • Foliar Spray: When sprayed on the leaves, compost tea can improve nutrient uptake directly through the foliage. This method is particularly useful for providing a quick nutrient boost and enhancing disease resistance.
  • Seed Treatment: Soaking seeds in compost tea before planting can promote healthier germination and stronger seedling growth. The beneficial microbes coat the seeds, offering protection against soil-borne diseases and enhancing early nutrient uptake.

Application Tips

Using compost tea effectively involves understanding the best practices for its application.


  • Brewing: To make compost tea, you need high-quality compost and a brewing system. Place the compost in a porous bag, submerge it in water, and aerate the mixture for 24-48 hours. Adding a sugar source like molasses can help feed the beneficial microbes during the brewing process.
  • Soil Drench Application: After brewing, dilute the compost tea if necessary and apply it directly to the soil around your plants. This method is particularly effective for improving soil health and supporting root development.
  • Foliar Spray Application: Use a fine mist sprayer to apply the compost tea to the foliage. Ensure thorough coverage, especially on the underside of leaves where pests and diseases often reside. For best results, apply in the early morning or late afternoon to avoid leaf burn from the sun.
  • Seed Treatment: Soak seeds in compost tea for a few hours before planting. This pre-treatment helps in enhancing seed germination rates and protecting young seedlings from pathogens.


4. Biochar – A Sustainable Solution for Improved Soil Health


Biochar is an incredibly versatile organic fertiliser that offers a multitude of benefits for both soil health and overall farm productivity. Here’s why you should consider incorporating biochar into your organic farming practices:

  • Increases Soil Water Retention: Biochar acts like a sponge, helping to retain water in the soil. This is particularly beneficial during dry spells, as it ensures that plants have a steady supply of moisture.
  • Improves Nutrient Holding Capacity: The porous structure of biochar enhances the soil’s ability to hold onto essential nutrients. This means that fertilisers are more effective, and plants have a better chance of accessing the nutrients they need for growth.
  • Reduces Soil Acidity: Biochar can help to neutralise acidic soils, making it easier for plants to absorb nutrients. This is particularly useful in areas where the soil pH is too low for optimal plant growth.
  • Enhances Soil Structure and Fertility: By improving soil aeration and reducing soil compaction, biochar creates a more favourable environment for root growth and microbial activity. This leads to healthier, more fertile soil.


Biochar’s versatility makes it a valuable addition to various farming practices. Here are some key uses:

  • Incorporation into Soil: Biochar can be mixed directly into the soil to improve its physical and chemical properties. This application is beneficial for enhancing soil health and supporting plant growth.
  • Composting: Adding biochar to compost piles can help to speed up the composting process and improve the quality of the finished compost. Biochar provides a habitat for beneficial microbes, enhancing microbial activity in the compost.
  • Livestock Feed Additive: When added to livestock feed, biochar can help to improve digestion and nutrient absorption. It also has the potential to reduce methane emissions from livestock, contributing to more sustainable farming practices.

Application Tips 

To maximise the benefits of biochar, here are some practical tips:

Soil Integration at Planting Time

Mix biochar into the soil at planting time to ensure that it is well-distributed. This helps to improve soil structure and nutrient availability right from the start.

Mixing with Compost

Combine biochar with compost to enhance the microbial life and nutrient content of the compost. This mixture can then be applied to the soil to provide a boost of fertility.


Before applying biochar to the soil, “pre-charge” it by soaking it in a nutrient-rich solution such as compost tea or a diluted organic fertiliser. This helps to ensure that the biochar is loaded with beneficial nutrients and microorganisms before it is added to the soil


Rotational Grazing water management

Adding Biochar to Livestock Feed

Incorporate biochar into livestock feed to improve animal health and reduce methane emissions. Start with small amounts and gradually increase the dosage as the animals become accustomed to it.

Feeding biochar or charcoal to livestock offers several benefits, here are 6 of the key benefits:

1. Reduction in Methane Emissions

Feeding biochar to cattle can lower methane production in the rumen. This is due to biochar’s ability to modify the fermentation process, which decreases the release of methane, a potent greenhouse gas.

2. Improved Feed Conversion Efficiency

Biochar in the diet of livestock has been shown to enhance feed efficiency. It helps in better digestion and nutrient absorption, leading to improved growth rates and overall health of the animals​.

3. Enhanced Soil Health

When biochar is used in cattle feed, the resultant manure, enriched with biochar, is applied to fields. This manure improves soil structure, increases water retention, and enhances microbial activity, contributing to better soil health and fertility​.

4. Reduction in Ammonia Emissions

Biochar reduces ammonia emissions from manure, which helps in decreasing odour and improving the nitrogen content in the manure. This leads to less nitrogen loss and better nutrient availability for crops​.

5. Detoxification

Biochar has a scavenging effect on toxins. It can absorb harmful substances like dioxins, pesticides, and other toxins from the cattle’s diet, reducing the overall toxin load in the animal and improving their health​.

6. Parasitic Reduction

There is evidence that biochar can help in reducing the burden of parasites such as worms and coccidiosis in livestock, which can lead to lower veterinary costs and healthier herds.

How to improve soil fertility, organically

5. Vermicompost – The Power of Worms


Vermicompost is an organic fertiliser that offers a plethora of benefits for enhancing soil fertility and promoting plant growth. This nutrient-rich compost is produced through the decomposition of organic material by earthworms. Here are some key benefits of using vermicompost on your farm:

  • Rich in Nutrients: Vermicompost contains a balanced mix of essential nutrients like nitrogen, phosphorus, and potassium, as well as micronutrients. These nutrients are readily available to plants, ensuring healthy growth and development.
  • Boosts Soil Fertility: The organic matter in vermicompost improves soil structure, increases water retention, and enhances microbial activity. This leads to more fertile soil, capable of supporting robust plant growth.
  • Enhances Plant Growth: By providing a steady release of nutrients, vermicompost supports long-term plant health. It also helps plants develop strong root systems, improves resistance to pests and diseases, and enhances overall plant vigour.


Vermicompost is a versatile product that can be used in various ways to improve your farming practices. Here are some practical uses:

  • Soil Amendment: Incorporating vermicompost into the soil enriches it with nutrients and organic matter. This is particularly beneficial for improving soil health in degraded or nutrient-poor soils.
  • Potting Mixes: Vermicompost is an excellent addition to potting mixes, providing essential nutrients and improving the moisture-holding capacity of the mix. This is ideal for container gardening and greenhouse cultivation.
  • Top-Dressing: Applying vermicompost as a top-dress around plants provides a continuous supply of nutrients throughout the growing season. This helps to maintain optimal nutrient levels in the soil and supports healthy plant growth.

Application Tips  

To get the most out of vermicompost, it’s important to apply it correctly. Here are some tips to help you maximise its benefits:


  • Producing Vermicompost: Set up a worm bin and maintain it with organic waste such as vegetable scraps, fruit peels, and garden clippings. Ensure that the bin is well-ventilated and kept moist but not waterlogged. Harvest the vermicompost once the organic material has been fully broken down by the worms.
  • Soil Integration: When planting, mix vermicompost into the soil at a rate of about 10-20% by volume. This helps to improve soil fertility and structure from the start. For existing plants, lightly work the vermicompost into the top few inches of soil around the base of the plants.
  • Top-Dressing: Apply a thin layer of vermicompost around the base of plants as a top-dress. This can be done at the beginning of the growing season and periodically throughout the season to maintain nutrient levels. Water the area well after applying the vermicompost to help it integrate into the soil.
  • Potting Mix: For potting mixes, combine vermicompost with other components like peat moss, perlite, and compost. A typical mix might include 10-20% vermicompost. This ensures that the potting mix is nutrient-rich and has good moisture-holding capacity.
Soft Rock Phosphate

6. Organic Soft Rock Phosphate Fertiliser – Slow Release Nutrients


Soft rock phosphate, also known as CalPhos or colloidal phosphate, is a valuable organic fertiliser that offers several benefits for improving soil health and plant development. Here are some of its key benefits:

  • Rich in Slow-Release Nutrients: Soft rock phosphate provides a steady supply of phosphorus and calcium, which are crucial for plant growth. Unlike synthetic fertilisers, its nutrients are released slowly, ensuring long-term availability.
  • Improves Soil Structure: By adding organic matter and minerals to the soil, soft rock phosphate helps enhance soil structure, making it more conducive to plant growth.
  • Enhances Nutrient Availability: This organic fertiliser improves the soil’s ability to hold and exchange nutrients, ensuring that plants receive the essential elements they need for healthy development.


Soft rock phosphate is a versatile product that can be used in various ways to benefit your farming practices. Here are some practical uses:

  • Soil Amendment: Incorporating soft rock phosphate into the soil boosts its phosphorus and calcium levels, essential for root development and overall plant health.
  • Composting: Mixing soft rock phosphate with compost enhances the nutrient content of the compost, providing a richer amendment for your soil.

Application Tips

To maximise the benefits of soft rock phosphate, it’s important to apply it correctly. Here are some tips to help you get the most out of this organic fertiliser:

  • Incorporate into Soil at Planting Time: For best results, mix soft rock phosphate into the soil at the time of planting. This ensures that the nutrients are readily available to the plants as they establish their root systems.
  • Mix with Compost: Combine soft rock phosphate with compost before applying it to your fields. This not only enhances the nutrient content of the compost but also improves its overall effectiveness as a soil amendment.
  • Target Acidic Soils: Soft rock phosphate is particularly effective in acidic soils where phosphorus availability is limited. By applying it to acidic soils, you can help balance the pH and improve nutrient uptake by plants.
  • Use in Garden Beds and Potted Plants: For smaller-scale applications, such as garden beds and potted plants, mix soft rock phosphate into the top few inches of soil. This method ensures that the nutrients are easily accessible to the plants’ roots.
  • Application Rates: Follow the recommended application rates for soft rock phosphate based on your specific soil conditions and crop requirements. Over-application can lead to nutrient imbalances, so it’s important to use the correct amount.

By following these application tips, you can maximise the benefits of soft rock phosphate and enhance the overall health and productivity of your farm.

Related online article – ‘How to use fertilisers – rock phosphate’


7. Molasses – Talk About a Cost-Effective Soil Amendment

Molasses, a byproduct of sugar production, and makes a great cost-effective soil amendment. Rich in sugars, nutrients, and minerals, molasses offers several benefits for soil health and plant growth. Its natural composition makes it an excellent addition to organic farming practices.

Molasses, particularly blackstrap molasses, contains fulvic acid, which is beneficial for soil health. Fulvic acid helps in chelating minerals in the soil, making them more available for plant uptake, which improves plant growth and health​.


  • Enhances Soil Microbial Activity: Molasses serves as a food source for beneficial soil microorganisms. The simple sugars in molasses provide energy, promoting the growth and activity of these microbes. This microbial boost helps decompose organic matter more efficiently, releasing nutrients that are readily available for plant uptake.
  • Improves Soil Structure: The sticky nature of molasses helps bind soil particles together, enhancing soil structure and increasing its ability to retain moisture. Better soil structure reduces erosion and runoff, leading to more stable and fertile soil conditions.
  • Increases Nutrient Availability: Molasses is packed with essential minerals such as calcium, magnesium, and potassium. When added to soil, these minerals become more accessible to plants, improving their overall health and resilience. Additionally, the chelating properties of molasses help prevent nutrient leaching, ensuring that plants receive a steady supply of nutrients.


  • Compost Activator: Adding molasses to compost piles accelerates the decomposition process. The sugars in molasses feed the microbes that break down organic material, resulting in richer, more nutrient-dense compost.
  • Foliar Spray: Diluted molasses can be used as a foliar spray to provide plants with a quick energy boost. This application helps enhance photosynthesis and overall plant vitality, especially during critical growth stages.
  • Soil Drench: Applying a molasses solution directly to the soil as a drench can improve soil health and promote robust root development. This method is particularly beneficial for gardens, orchards, and vineyards where soil quality is paramount.

Application Tips

  • Dilution Ratio: Mix 3 tablespoons of molasses per 5 litres of water for soil drenching and foliar sprays. Adjust the concentration based on the specific needs of your plants and soil.
  • Application Frequency: Apply molasses solutions every 2-4 weeks during the growing season. For compost activation, add molasses every few weeks as you turn the pile.
  • Timing: Apply molasses solutions in the early morning or late afternoon to avoid the heat of the day. This helps prevent rapid evaporation and ensures that soil microbes and plants can take up the nutrients effectively.

By integrating these organic fertilisers into your farming practices, you can build a comprehensive, cost-effective approach to soil regeneration.  This multi-purpose arsenal not only saves costs but also promotes long-term soil productivity, ensuring sustainable agricultural practices, and a resilient farming system, for future generations.

Happy Farming!

Header background image credit: ‘The Perfect Sheep Pasture’

Join us as we delve into the inspiring journey of pecan and sheep farmers, Wayne and Sue Green, who have harnessed the full potential of SONIC Liquid Fish and Seaweed Biofertilisers to achieve remarkable success.

In this video interview, these innovative farmers share their firsthand experiences and insights on how these organic fertilisers have transformed their agricultural practices. They have explored various applications, including foliar spray, irrigation, and boom spray, as well as feeding the liquid seaweed supplement to their sheep.

This comprehensive approach, and the outcomes so far, has underscored the versatility and effectiveness of using time-tested organic fertilisers in modern agriculture.

G’day! I’m Sonja, author and SONIC Natural Farming co-founder.

With deep roots in the agricultural community for over 30 years, I understand the unique challenges and rewards of farming in our beautiful country.

As generational Australian farmers, experiencing these challenges first hand, is why we developed a company that can sustainably produce biofertilisers, and supply them to farmers, cost-effectively.

Our innovative approach to fertilisation and soil care enables farmers to boost their soil fertility and their bottom line, making it a win win for Australian farmers and the environment.

SONIC Natural Farming

Want to see how we can help you beat the high cost of fertiliser?

SONIC Natural Farming


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