Design and experiment of the straight oblique offset no-tillage sowing furrow opener with side deep fertilization

No-tillage sowing can effectively alleviate the spring drought for the high corn yield in northeast China. Side-deep fertilization can also avoid seed burning for the fertilizer supply in the middle and late periods of crops. Once the side deep fertilization is applied into no-tillage sowing, the soil height on both sides of the sowing belt can be inconsistent after the fertilizer shovel operation, leading to aggravating the lateral deflection of the seeder under the uneven distribution of surface straw stubble.It is very necessary to improve the sowing depth uniformity and lateral consistency. In this study, the straight-oblique offset furrow opener was designed to reduce the resistance to the increase in the soil backfill during no-tillage sowing, in order to improve the sowing depth uniformity and lateral consistency. The furrow opener was mainly composed of a cutting oblique edge, a retaining positioning plate, and an offset bulldozing plate. The soil was cut and pushed into the side of the fertilizer furrow to widen the seed furrow during the operation. The seeds falling was avoided after the fertilizer furrow for better sowing quality. Firstly, the force analysis was implemented on the offset bulldozing plate of the furrow opener. Among them, the horizontal force balance analysis of the side deep fertilizer shovel and the sowing furrow opener was also made to design the structure of the furrow opener. The height of the retaining positioning plate and the offset bulldozing plate of the furrow opener was determined to be 160 mm, and the bottom edge spacing between the retaining positioning plate and the offset bulldozing plate was 30 mm equal to the short side width of the shovel handle, the insertion gap angle was 8°, and the inclination angle was 10.6°. Secondly, the soil disturbance was analyzed before and after the operation of the straight-oblique offset furrow opener. The straight-oblique offset furrow opener increased the soil backfill of the fertilizer furrow and seed furrow. Finally, the sliding cutting of cutting oblique edge was clarified in the motion analysis of soil particles on the offset bulldozing plate. The structural parameters of the operation performance of the furrow opener were the oblique edge sliding angle and the offset angle. A discrete element simulation model of soil-stubble-straw was established using EDEM. The three-dimensional models of stubble cutter, fertilizer shovel, and furrow opener were imported into EDEM for simulation experiments. The structural parameters of the furrow opener were optimized by a two-factor and five-level orthogonal rotation combination experiment with forward resistance, the backfill depth of the fertilizer furrow and the backfill depth of the seed furrow as experiment indexes. The optimal combination of parameters was achieved in the oblique edge sliding angle of 37° and the offset angle of 15°. A field experiment was conducted with the double disc and sharp-angle furrow openers under optimal parameters. The sowing depth variation coefficient of straight-oblique offset furrow openers was 41.12% and 19.41% lower than those of double disc and sharp angle furrow openers, respectively. The sowing lateral variation coefficients decreased by 39.00% and 28.41%, respectively. The forward resistance was reduced by 7.26% and 28.20%, respectively. The backfill depth of the fertilizer furrow increased by 9.47% and 13.68%, respectively after optimization. The backfill depth of seed furrow increased by 33.33% and 7.14% respectively. The furrow opener reduced the forward resistance, while improving the soil backfill of the fertilizer furrow and seed furrow for the sowing depth uniformity and sowing lateral consistency. The finding can provide a strong reference for the design of the seeding furrow opener.