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To address the issues of significant fertilizer discharge fluctuations and poor stability in traditional spiral fertilizer dischargers, a four-head inclined spiral precision fertilizer discharger was designed. Through motion analysis and theoretical calculations, the key parameters affecting the stability of fertilizer discharge rate were identified, along with their optimal value ranges.Experimental factors included the number of spiral blades, discharger inclination angle, spiral blade diameter, spiral blade pitch, and spiral blade rotational speed, with the coefficient of variation of fertilizer discharge rate as the evaluation metric. Discrete element method （DEM） simulations were conducted for both single-factor and multi-factor scenarios. The single-factor simulation results indicated that the number of spiral blades, discharger inclination angle, spiral blade diameter, and spiral blade rotational speed all significantly impacted the stability of fertilizer discharge rate. It was found that using a four-head inclined spiral to convey fertilizer can enhance discharge stability. Multifactor simulation results showed that the optimal parameter combination for a four-head spiral configuration was with discharger inclination angle of 38°，spiral blade diameter of 46 mm, and spiral blade rotational speed of 31 r/min. Under this combination, the coefficient of variation of fertilizer discharge rate reached minimum value of 1.65%. Finally, bench tests were conducted to validate the simulation results under the optimal parameter combination. The tests revealed that the measured coefficient of variation for fertilizer discharge rate was 3.69%. Further optimization determined that at spiral blade rotational speed of 33 r/min, the coefficient of variation could be minimized to 2.92%. Both simulation and bench test results demonstrated that the improved four-head inclined spiral precision fertilizer discharger performed well in terms of fertilizer discharge stability, which can meet orchard fertilization standards, and satisfy the operational requirements for orchard fertilization.