Effect of vane shape and fertilizer product on spread uniformity using a dual-disc spinner spreader

Abstract

Advancements in granular applicators are required in order to provide accurate metering and placement of fertilizer as emphasis grows on nutrient and associated environmental stewardship. Spinner-disc spreaders are commonly used to apply granular fertilizers with current spread widths up to 30 m. Spreader hardware components (divider, spinner disc and vanes) influence material distribution but increased spread widths have increased the risk for non-uniform application of nutrients. Therefore, the objectives of this research were to 1) evaluate the impact of vane design on fertilizer particle behavior and spread distribution uniformity for a dual-disc spinner spreader, 2) compare and contrast physical and chemical methods for measuring nutrient concentration of blended fertilizer samples and 3) determine the segregation potential of a blended fertilizer applied using a dual-disc spinner spreader while varying feed rate and disc speed. Two types of testing were conducted; stationary and standard pan testing. A typical fertilizer dual-disc spreader was used in this study. Treatments included feed rates of 224 and 448 kg ha-1 and three spinner-disc speeds, 600, 700 and 800 rpm. Four vane designs were also evaluated. Results indicated that two distinct patterns of the overall spread pattern existed due to controlled and uncontrolled flow of fertilizer off the vanes. Further, vane design impacted spread uniformity. The top edge of Vane 2, tapered at 15º backwards, reduced ricocheting by approximately 50% compared to Vane 1. Vane 2 also produced the most consistent spread uniformity compared to other three vane designs over the varying disc speeds. Vane 4, with an enclosed U-section, generated the maximum effective spread width of 24.4 m at a spinner disc speed of 800 rpm versus 22.9 m for Vanes 1, 2 and 3. Overall, Vane 2 was recommended for fertilizer application using this dual-disc spinner spreader. The chemical method for analyzing nutrient concentration generated consistently lower nutrient concentration values for P2O5 and K2O compared to a physical separation method. The mean difference between the methods was a factor of 1.15. Distinct nutrient patterns were generated for the different blended fertilizer constituents; “W” shape for P2O5 and “M” for K2O regardless of feed rate and spinner disc speed. Nutrient spread distribution patterns did not vary with feed rate (p>.05) whereas the increase in spinner disc speed caused significant differences (p<.0001) as the pattern widened as speed increased. DAP particles travelled farther than potash with maximum transverse distance of 16.4 m at 800 rpm.