Investigation of Granular Organic Fertilizer Distribution Uniformity in Disk-Type Spreaders with Standard and Modified Vane Configurations

Organic granular fertilizers are increasingly used in sustainable agriculture, yet their physical properties and spreading behavior remain underexplored. This study aimed to evaluate the mechanical resistance and field distribution efficiency of grain husk granules compared to poultry manure granules, using a disk-type spreader (Kuhn MDS 9.19). Laboratory tests assessed the granule geometry, density, moisture content, and compressive strength, while field experiments measured distribution patterns under controlled conditions. Two disk configurations were tested: the manufacturer’s original design and a modified version with custom-designed vanes. The results showed that grain husk granules had sufficient compressive strength (189.45 ± 92.53 N) for practical use; however, it was lower than poultry manure granules (382.56 ± 78.08 N). The distribution analysis revealed that grain husk granules provided more uniform lateral coverage, while poultry manure granules exhibited higher central accumulation. Modified vanes significantly improved the spreading uniformity and application rates for both fertilizer types. A statistical analysis confirmed that differences in the distribution were driven by granule properties and the vane geometry. This study concludes that grain husk granules are a viable alternative organic fertilizer and that spreader design optimization can enhance application efficiency and reduce environmental risks. These findings contribute to the development of more precise and sustainable fertilization technologies.