Extended Analysis of the Effect of Seeder Tilt on the Seeding Rate — Simulation Results and Experimental Validation

Abstract

Broadcast seeders are commonly used in Poland for fertilisation, but they do not ensure precise and uniform fertiliser distribution. Strip-tillage systems utilise mechanical and pneumatic seeders, which allow seeds to be placed at the appropriate depth and in even rows. However, these devices follow the surface of the ground and are therefore susceptible to uneven fertiliser distribution depending on the terrain (slope). Uneven fertiliser distribution results in localised overfertilisation or nutrient deficiencies (nitrogen, phosphorus, potassium); the former, if excessive, can lead to plant lodging or frost damage, while the latter can lead to weakened plant growth and reduced yields. Competition between plants for sunlight and water can further inhibit the development of weaker individuals. This article presents the results of research on the effect of the tilt of the seed hopper and the measuring system (ranging  from  -15°  to  +15°, with 5° intervals) on the dose of granular material sown. Negative angles refer to uphill travel, while positive angles refer to downhill travel. Simulation and laboratory studies have shown that when going uphill, the amount of material spread increases by 5.45% (simulation studies) and 7.86% (laboratory studies). When going downhill, the amounts decrease by 11.63% and 11.86%, respectively. Simulation studies were conducted using Ansys Rocky 2024 software (version R1), based on the discrete element method. The boundary conditions for the simulation, including the static and dynamic friction coefficients and the restitution coefficient of the test object (granular mineral fertiliser in the form of urea), were obtained from literature data. In the first phase of the study, the computational space modelled according to the dimensions of the seeder was unfavourable. Significant improvement in the agreement between the simulation and laboratory data was achieved by increasing the size of the computational space. The simulation results were validated using a laboratory test stand built based on the simulation model. The results were subjected to ANOVA statistical analysis, which confirmed that the effect of the slope on the seeding dose is  statistically  significant with a significance  level  of  p = 0.000. Based on the obtained simulation and laboratory test results, a mathematical equation was generated to calculate the dose distribution depending on the slope of the terrain. After applying the Wilcoxon signed-rank test, it  was  confirmed,  with  a  significance level of p = 0.173, that the discrete element method can be used successfully to simulate the dosing (seeding) process with sufficient accuracy.