Organic Fertiliser: How are they Manufactured?

Australia, a world leader in organic agriculture wherein the organic fertilisers market was valued at $8.3 billion in 2020 is expected to grow to $15.9 billion by 2030.

Fertilisers as we know are the materials that are added to soil or plants to provide nutrients and sustain growth. Organic fertilisers as the name suggests, are naturally produced fertilisers that typically include animal waste like meat processing waste, manure, slurry, and guano; and plant-based fertilisers like compost and biosolids. Since organic fertilisers are chemical-free, they aid in cultivating the farm in such a manner that it enriches the soil, and plants, and are helpful as insect repellents. Organic products feed the soil by creating a sustainable environment and are hence beneficial for agricultural lands.

In this blog, we have discussed how organic fertilisers are manufactured. Before doing so, let us discuss the different types of organic fertilisers.

Types of Organic Fertilisers

There are different types of organic fertilisers that add nutrients and other essential ingredients to the soil to promote healthy crop growth.

1. Plant-based Fertilisers: This type of fertiliser is made from plants that contain moderate nitrogen, phosphorous and potassium. These elements break down quicker than any other organic substance and become available to the soil for crops to use. Compost, seaweeds extract, hummus, and amino acids are some of the plant-based fertilisers. 

2. Animal-based Fertilisers: Animal excreta, manure, and bone meal constitute animal-based fertilisers. This type of fertiliser adds a great amount of nitrogen to the soil and is perfect for leafy vegetables and plants. 

3. Mineral-Based Fertilisers: Used primarily for increasing or lowering the pH level in soil, mineral-based fertilisers add to the growth of heavy plants, for example, calcium and epsom. It also adds nutrients to the soil. 

How is Organic Fertiliser Manufactured?

Organic fertilisers are manufactured following the below-mentioned points-

1. Pre-treatment of Raw Materials: Except the ones that contain high toxins, almost all organic wastes can be used as composting materials. Other materials like straw and husk of grains/cereals; corn stalk, bagasse, sawdust, etc. are used to enhance the soil organic matter. These raw materials are dried and stored in a nearby place. To reduce the compost time, the waste is shredded to a uniform size and mixed in a controlled way. Shredders, grinders, or chippers are used to cut wood and shoots of fruit trees. 

2. Compost Process Design: One of the popular composting methods that are suitable for a wide range of feedstocks and facility capacities is windrow composting. This method involves dumping the waste on the ground in the form of piles of 1.5m to 2.5m in height. Turning the windrows help with mixing the materials and supplying oxygen to the bacteria, ensuring that every part of the windrow reaches the required 55 degrees Celsius which is essential for destructing the pathogen. Ensure that turning is done every two to three days in the first two weeks when the temperature is above 55 degree Celsius and above. After this, frequent turning of the compost is not as essential. The entire process takes about 4-6 weeks. 

3. Finished Compost Grinding, Drying, and Screening: Since finished compost is quite wet and coarse to be granulated directly without further conditioning, preparing the compost for granulation involves the below-mentioned steps:

• Grinding the produce
• Screening that helps remove larger particles
• Removing moisture by drying the compost artificially 

4. Mixing Compost with Other Organic Nutrients: Boosting the nutrient content of composts when targeting the granulated fertiliser market by adding other organic nutrients and mineral fertilisers is essential. Humic acid helps enhance soil fertility and is an ideal additive that boosts bio-activity and enhances the performance of compost. It is an effective agent that complements synthetic or organic fertilisers. Adding mineral fertilisers like rock phosphate and potash sulphate impacts on enhancing the particle size distribution of the mix significantly. To do so, a horizontal mixer is used. 

5. Compost Fertiliser Granulating Method and Equipment: Through granulation, a significant simplification of the storage, transportation, and dosage is done that helps improve both usability and storability. Granulating compost enhances its slow-acting properties and avoids nitrogen starvation. New-type organic fertiliser dedicated granulators, flat die extrusion granulators, disc granulators, and roller extrusion granulators are the few popular organic fertiliser granulators. 

6. Organic Fertiliser Granules Drying Procedure: Water retention plays a significant role not only in the quality of the final product, but also in its effectiveness. Organic fertilisers in granular form should have a certain percentage of moisture. The drying process is thus an essential step in processing organic fertilisers. The rotary fryer helps reduce the liquid moisture content of fertiliser granules, which brings them into direct contact with a heated gas. 

7. Organic Fertiliser Granules Cooling Process: To remove the heat from the organic fertilisers after the drying process, a rotary cooler is used, This machine slopes slightly so that the discharge end is lower than the material feed end which conveys the fertiliser through the cooler gravity. When the rotary cooler rotates, the organic fertilisers to be dried enter the cooler, and the fertiliser is lifted by a series of internal fins lining the inner wall of the cooler. Once the fertiliser reaches high enough to roll back off the fins, it falls back to the bottom of the cooler and passes through the cold air stream. 

8. Screening: Organic fertiliser granules should be screened before bagging or bulk loading. This helps in getting the desired particle size and removes the product size fraction. Fertilisers are separated by screening into product size ranges that help as fertilisers and the granules (regardless of the size) are reprocessed. 

9. Packaging: Organic fertilisers that are manufactured with uniform size are fed in the automatic packaging machine transporting by belt conveyor, and are then bagged. 

Wrapping Up,

For more information about organic fertiliser in Australia, browse through the KG2 website, Australia’s largest independent farmer’s database, or get in touch with us for a personalised walk-through of the popular organic fertilisers in Australia that have helped several successful farmers over the years.