Design and experiment of deep fertilization ditching device for rice mechanical direct seeding

<bold>Objective</bold> In order to solve the problems of entanglement of grass，shallow fertilization and blockage of fertilizer in the deep fertilization ditching device of rice mechanical direct seeding in southern rice area，a deep fertilization ditching device for rice mechanical direct seeding was developed based on theoretical analysis and experimental research. <bold>Method</bold> Based on the theory of edge curve of ditching device，the ditchers with circular，quadratic and exponential function edge curves were analyzed and designed，and the matching deep fertilizer ditching device was developed.In order to clarify the spatial distribution and anti-tangling performance of spreading fertilizers，bench tests were conducted to study the percentage of fertilizer content in different fertilizer application depths under different soil depths of the mudguard；multifactorial tests were conducted on the anti-tangling performance with the advancing speed of the furrowing device，the number of straws and the cutting edge curve as the independent variables，and the probability of the furrow opener’s sliding cut straws and the distance of the sliding cuts as the dependent variables. <bold>Result</bold> With the increase of the depth of the mud cover from 2 cm to 6 cm，the percentage of fertilizer content in the depth of 5-10 cm showed a trend of increasing first and then decreasing，and the optimal soil depth of the mudguard was 4 cm；When the forward speed of the furrowing device increased，the probability of the furrow opener slip cutting the straw increased and the slip cutting distance decreased；when the number of straw in the paddy field was large，the probability of the furrow opener slip cutting the straw decreased and the probability of the anti-tangling increased；Compared with the circular function and exponential function edge curve，the sliding distance of the opener of the quadratic function edge curve was smaller.With the increase of the forward speed，the slip cutting distance decreased，which means that it is good in stability；therefore the quadratic function edge curve opener had the best structure. <bold>Conclusion</bold> The deep fertilization ditching device developed in this study can meet the agronomic requirements of simultaneous deep fertilization of rice direct seeding，thus providing reference for the research on deep fertilization technology and equipment for rice.