Discrete element modelling of tillage forces and soil movement of a one-third scale mouldboard plough

In Australia there is renewed interest in mouldboard ploughing to improve crop yields of non-wetting sandy soils. Burying the top layer of non-wetting soil and bringing to the surface soil that has better water holding capacity is beneficial for plant growth. To improve the effectiveness of the ploughing it is essential to: (1) optimise the tillage forces and (2) understand the soil inversion and burial process. Recent studies show that Discrete Element Modelling (DEM) has the potential to predict both tillage forces and soil movement of tillage implements. In this study a one-third scale mouldboard plough was constructed and tested in a soil bin where draught force, vertical force and soil movement were measured. A comparison of the measured and simulated draught and downward vertical forces showed a close agreement. A procedure was developed to compare soil movement, percentage burial of top soil and forward soil movement of the soil bin tests and the DEM simulations. The results showed similar trends and patterns for both the percentage of the top soil buried to various tillage depths and the forward soil movement. Due to the larger than actual spherical particles used in the simulation the forward soil movement was greater for DEM. The DEM showed some particles moving below the tillage depth. This shows that further model development is needed with work recommended to look at using both clump particle shapes and smaller particle sizes to improve soil movement predictions.(C) 2016 IAgrE. Published by Elsevier Ltd. All rights reserved.