Design and experiment of centrifugal fertilizer spreading mechanism with double drop point feeding

<bold>Objective</bold> In order to address the problems of low uniformity of variable rate fertilization in rice，a centrifugal fertilizer spreader with double falling points was developed by leveraging the advantages of simple structure，wide spreading range and high operation efficiency of disc fertilizer spreader. <bold>Method</bold> Based on the EDEM discrete element simulation model，the single-trip fertilizer simulation test was analyzed.Taking the radius of the blanking point，the angle of the blanking point，the amount of fertilizer and the speed of the centrifugal disc as the influencing factors，the influence of single factor on the distribution of fertilizer particles was determined by single factor simulation test.The orthogonal rotation simulation test was conducted under the condition of screening out the angle factor of the blanking point，and the influence of the interaction of the above factors on the coefficient of variation and the width distance of the fertilizer distribution uniformity was clarified.The optimized target parameters were used to conduct bench test verification and field test，and the coefficient of variation of fertilizer distribution uniformity after superposition was analyzed with actual reciprocating operation conditions. <bold>Result</bold> The results of single factor and orthogonal rotation test show that a larger angle between discharge points negatively impacts fertilizer spreading uniformity.The effects of different factors on the coefficient of variation of fertilizer distribution uniformity，ranked by their impact from greatest to least，are as follows：fertilizer application amount，the radius of dropping point and the rotating speed of centrifugal disc.When the radius of the dropping point is 112 mm，the amount of fertilizer applied is 475.05 kg/hm² and the rotating speed of the centrifugal disc is 540 r/min，the coefficient of variation of uniformity is the smallest，which is 15.49%，and the effective width is 8 m，the results of bench test are 15.83% and 7.7 m，and the coefficient of variation of fertilizer distribution is 9.12%. <bold>Conclusion</bold> The field experiment shows that the radius of dropping point of 100 mm is more suitable than other radius in the range of fertilizer application.