Development and Numerical Simulation of a Precision Strip-Hole Layered Fertilization Subsoiler While Sowing Maize

The traditional fertilizer application methods have serious problems of environmental pollution and soil degradation due to low utilization rates in the Huang–Huai–Hai Plain of China. In this study, the conservation tillage strip-hole layered fertilization method was proposed and a precision strip-hole layered fertilizer subsoiler was designed. To meet the requirements for deep tillage strip-hole layered fertilizer application, theoretical analysis and parameter calculations were first carried out on the fertilizer application type hole wheel, and then the main factors affecting the fertilizer application effect of a strip-hole layered fertilizer shovel were analyzed. The effect of forwarding speed, angle of fertilizer tube installation (AFT) and angle of unloading fertilizer (AUF) on the middle and lower layers of the fertilizer distribution length (FDT) and fertilization amount deviation stability coefficient (FADSC) was studied using the discrete element method (DEM). The three-factor three-level full-factors test design method was adopted. Simulation results showed that the FDT and the FADSC increased as the forward speed increased; the FDT decreased as the AFT and the AUF increased; an increased FADSC was observed at a middle angle of the AFT and the AUF. The minimum FADSC was obtained for a combination of parameters with a forward speed of 2 km/h, the AFT of 35° and the AUF of 60°, corresponding to the FADSC of 2.49% in the middle layer and 2.93% in the lower layer while satisfying the FDT condition. The results of the field trials showed that the FADSC was 11.36% and 12.42%, respectively, an increase of 8.87% and 9.49%, respectively, compared to the simulation results, validating the simulation model. The new way of fertilizer application methods and a theoretical basis were provided for the design of hole application machinery.