Evaluation of the Efficiency and the Performance of a Variable-Rate Chemical Fertilizer Spreader Using a GPS-Based Control System

Abstract

Finned centrifugal disc fertilizer spreaders are widely used worldwide for distributing granular mineral fertilizers due to their simple construction and high operational efficiency. The investigation studied the effect of three parameters forward speed  9,12, and 15 km h^-1, disc rotational speed 500, 550, and 600 rpm, and fin angle 0,+25, and -25 degree on the performance of a GPS-controlled variable-rate fertilizer spreader at two application rates 25% and 75%, representing low and high fertilizer levels, respectively. The image processing was used to quantify fertilizer amounts instead of conventional methods. The results showed that both theoretical and effective field capacities increased with forward speed. The best uniformity (CV = 15.6%) was achieved at the forward speed of 12 km h¹, disc speed of 550 rpm, and fin angle of –25° at 25% the gate opening, while values exceeding 170% were observed at 75% of the gate opening. Correlation analysis revealed strong positive relationships between forward speed and both theoretical and effective field capacities (r = 0.99), and between disc speed and most performance traits (r > 0.99). Operating costs ranged between 1395 and 1498 IQD ha^-¹. Overall, operating at a moderate forward speed, high disc speed, and medium fin angle provided an optimal balance between uniformity, efficiency, and economy. It was concluded that adjusting the forward speed, disc speed, and blade angle plays a crucial role in improving spread uniformity and work efficiency, it also that variable rate technologies can increase fertilizer distribution accuracy and reduce costs.