Study of tillage tool-soil-crop residue interaction

Soil and surface straw movement by a single sweep tool were experimentally studied, and then physically based mathematical models were developed and validated. Soil bin and field experiments were conducted using cereal straw and a 325-mm-wide sweep to study soil and straw interaction. Experimental factors were tillage speed and straw length. Results indicated that higher tillage speed resulted in larger soil and straw displacement and more straw being buried; there was less longer straw buried than shorter straw at the same tillage speed. The results of the soil bin experiment showed that the forward soil displacement would be reduced by at least 70% if tillage speed was reduced from 10 km/h to 5 km/h regardless of straw length.; The soil-moving zone in front of a single sweep was studied, and a steady-state model was proposed to calculate the quantities of soil and straw in the moving zone. Two additional steady-state models were developed based on existing soil failure models. These models were validated by the soil bin experiment. A soil displacement model was then developed and validated with the data obtained from the above soil bin and field experiments. The relative error of the soil displacement model was less than 19%. According to the soil displacement model, straw displacement was also modeled, and its the accuracy was between 73% and 93% depending on the length of straw. The parameters involved in both soil and straw displacement models were soil properties, tool geometric parameters, tillage speed, and tillage depth. Straw length was also included in the straw displacement model. Finally, soil and straw redistribution after tillage with a single sweep was modeled based on the soil and straw displacement models. The redistribution model fitted well with the results of the soil bin experiment. It could be concluded that the models developed above would predict the soil and straw interaction during tillage with a single sweep. It should be noted that the validating tests were conducted only at a constant tillage depth under the same soil conditions.