| Rapeseed is one of the main oil crops in China,and fertilization plays a crucial role in rapeseed sowing.Scientific fertilization is an important factor to ensure the quality of rapeseed seedlings and to achieve stable and increased rapeseed production.Aiming at the practical problems such as extensive application of rapeseed fertilizers,low fertilizer efficiency and low fertilization accuracy in our country at this stage,combined with the agronomic requirements of rapeseed sowing and fertilization,the side deep hole fertilization process for rapeseed was proposed,and a kind of mechanical direct seeding hole fertilization device for rapeseed was designed.The hole fertilization device realized the hole-fertilization function in the process of rapeseed sowing.The main research contents and conclusions were as follows:(1)Three different types of compound fertilizer mechanical and physical properties parameters measurement research was carried out.The Sanning compound fertilizer,Munvhong compound fertilizer and Xinshidai compound fertilizer commonly used in rapeseed broadcasting in Hubei Province were selected as the research objects,and their mechanical and physical parameters such as equivalent diameter,moisture content,sphericity,thousand-grain mass,bulk density and angle of repose were tested respectively.The test results showed that the average triaxial dimensions were3.74mm×3.51mm×3.19 mm,and the equivalent diameters were 3.17 mm,3.68 mm,3.56 mm.The repose angles of different compound fertilizers were 29.67°,33.21°,32.40°,and the average angle of repose was 31.76°.The sphericity of different compound fertilizers was greater than 90%.There were differences in the mechanical and physical parameters of different types of compound fertilizers,granular fertilizers such as compound fertilizers had high sphericity,which were suitable for mechanized hole fertilization.(2)The side deep hole fertilization process for rapeseed was proposed.It was determined that the fertilizer particles according to the rapeseed root transverse distance was 140 mm and the vertical distance was 80-100 mm,the fertilization hole distance was200 mm,and the fertilizer was deeply applied to the lateral position of the rapeseed seeds while the fertilizer particles were distributed in a cave.Based on the process of fertilization in the side deep hole of rapeseed,the overall design scheme of the mechanical direct seeding hole fertilization device for rapeseed was determined,the working process of the hole fertilization device was explained,and the spatial layout of the fertilizer point-applied device,the driven seed and fertilizer ditching roller,and the deep fertilizing shovel was clarified.Combined with the agronomic requirements of rapeseed sowing and fertilization,it was concluded that the number of fertilizer lines was 5,the fertilization depth was 80-100 mm,and the hole of fertilizer amount was 1.80-9.00 g.(3)The structural design and parameter analysis of the key components of the rapeseed mechanical direct seeding hole fertilization device were carried out.A kind of hole fertilization and fertilization device with inclined hole structure was proposed,and the structural parameters of the model hole and fertilizer feeding unit were determined.The diameter of the fertilizer feeding unit was 80 mm,and the number of radial model holes of the fertilizer feeding unit was 4.The overlapping length of the fertilizer feeding unit model’s hole and the fertilizer amount adjustment wheel can adjust the amount of fertilizer discharge in the hole,and the mechanical model of the force of the fertilizer group during the process of fertilizer filling and fertilizer discharge was constructed,and the parameters relationship between fertilizer filling angle,fertilizer discharge angle and the fertilizer feeding unit speed,the inclination angle of the left wall of the molding hole,the right side of the molding hole were obtained.Combined with the side deep hole fertilization process for rapeseed,it was determined that the diameter of the leveling roller of the driven ditching roller was 160 mm,and the radius and thickness of the fertilizer ditch disc were 200 mm and 20 mm.Based on the kinematics and dynamics principle,the seed and fertilizer ditching roller was analyzed.it was concluded that the working speed of the ditching roller was22～130r/min.Aiming at improving the stability of the fertilization depth,an envelopeshaped deep fertilization shovel was designed,the thickness of the front wall of the deep fertilizing shovel was 20 mm,and the angle between the left and right wing plates was5.2°.The geometric parameters relationship between the deep fertilization shovel and the seed fertilizer ditching roller was analyzed,and it was concluded that the gap between the deep fertilization shovel and the seed fertilizer ditching roller was 10 mm,the central angle of the enveloping arc segment between the deep fertilizing shovel and the seed fertilizer ditching roller was 55.15°.In order to explore the effect of different fertilizer tubes on the fertilizer cavitation performance,three different materials of fertilizer tubes,namely PVC fertilizer tube,ABS fertilizer tube,stainless steel fertilizer tube,were determined through analysis.(4)Based on EDEM software,the simulation experiment of the hole-forming performance of the fertilizer discharge device was carried out.The effects of the rotation speed of the fertilizer feeding unit,the length of the fertilizer filling hole and the material of the fertilizer tube on the error of the hole fertilizer amount and the fertilizer distribution long axis were analyzed.The single-factor simulation test results showed that the optimal ranges of the rotation speed of the fertilizer feeding unit was 30～90 r/min and the length of the fertilizer-filling hole was 15～35mm.The effect of different materials of fertilizer tubes on the error of the hole fertilizer amount was not obvious,but had a significant impact on the fertilizer distribution long axis after the granular fertilizer is dropped.The order of influence was: stainless steel fertilizer tube>ABS fertilizer tube>PVC fertilizer tube.The three-factor and three-level full-factor simulation test analysis showed that the parameter combination with better hole-forming performance were 60r/min of rotation speed of fertilizer feeding unit,18 mm length of fertilizer filling hole,and ABS fertilizer tube.The error of the hole fertilizer amount was 7.05%,and the fertilizer distribution long axis was62.45 mm,respectively.The cavitation performance was well.Under the optimized parameter combination,the EDEM simulation verification test was carried out,it was concluded that the error of the hole fertilizer amount was 6.98%,and the fertilizer distribution long axis was 62.59 mm.(5)The bench test of fertilizer discharge device and the field test of mechanical direct seeding hole fertilization device of rapeseed were carried out.Based on the optimal parameters combination obtained from the EDEM simulation test,the bench verification test of the hole-forming performance of the fertilizer point-applied device was carried out,the results turned out that with the increase of the speed of the fertilizer feeding unit,the error of the hole fertilizer amount,the coefficient of variation of the stability of the fertilizer distribution long axis and the error of the fertilizer pointed distance increased respectively,and the fertilizer distribution long axis first decreased and then increased.Under the condition that the speed of the fertilizer feeding unit was 30～90r/min,the error of the hole fertilizer amount was 4.56%～15.69%,the fertilizer distribution long axis was76.32～91.50 mm,the stability coefficient of fertilizer distribution long axis was4.53%～9.78%,and the error of the fertilizer pointed distance was 3.24%～7.31%.The field test of rapeseed mechanical direct seeding hole fertilization device was carried out using the Xinshidai compound fertilizer as the test object.It could be concluded that with the increase of the speed of the fertilizer feeding unit,the error of the hole fertilizer amount,the coefficient of variation of the stability of the fertilizer distribution long axis,the error of the fertilizer pointed distance and the stability coefficient of fertilization depth increased respectively,and the fertilizer distribution long axis first decreased and then increased.The variation trend of the cavitation performance index was the same as that of the bench test results.Under the condition that the speed of the fertilizer feeding unit was 30～90r/min,the error of the hole fertilizer amount was 4.73%～16.07%,the fertilizer distribution long axis was 85.21～101.65 mm,the stability coefficient of fertilizer distribution long axis was4.82%～10.63%,the error of the fertilizer pointed distance was 3.36%～7.58%,the fertilization depth qualified rate was 95.83%～97.92% and the coefficient of variation of the fertilization depth stability was 6.43%～10.85%,respectively.The cavitation performance was well,which met the requirements of hole fertilization in the processing of rapeseed sowing. |
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