PERFORMANCE OF HELICAL METERING MECHANISMS IN THE APPLICATION OF MICROGRANULAR FERTILIZER

ABSTRACT The use of microgranular fertilizers is currently increasing, with low application rates as an obstacle in the mechanization. This study aimed to verify the performance of helical metering mechanisms using microgranular fertilizer. Four different fertilizer-metering mechanisms were tested at two pre-established dose rates (35 and 50 kg ha−1) and seven longitudinal angles (−15°, −10°, −5°, 0°, +5°, +10°, and +15°). The experiment was carried out according to Brazilian standards. The results showed that the longitudinal inclination affects the actual fertilizer dose in all tested metering systems. Metering mechanisms with a helicoid with longitudinal and lateral overflow presented a similar dose, according to the variation of the longitudinal inclination. The metering mechanism with two helicoids showed the highest dose variation, while the metering mechanism with a helical thread and longitudinal overflow, filled between the shaft and the helicoid, had the best performance.