Modelling Tillage Translocation

Tillage translocation is the resultant displacement of soil by tillage (Fig. 1). Translocation is expressed as a mass of soil moved by tillage in a specified direction relative to the direction of tillage, i.e. the mass of soil translocated forward (parallel to the direction of tillage) per meter width of tillage or the mass of soil translocated laterally (perpendicular to the direction of tillage) per meter length of tillage. Translocation can also be expressed as a depth-averaged length, i.e. the distance the till-layer is translocated forward or laterally. Neither form of expression fully characterizes tillage translocation. To illustrate, a single pass a chisel plough may move 70 kg of soil forward per meter of tillage width. The average forward displacement of this 70 kg of soil may be 40 cm, but significant quantities of the soil may be moved as little as 5 cm and as much as 300 cm. Soil displacement varies across the width of a tillage implement due to the spacing and arrangement of tools. Therefore, all translocation measurements are based on the unit width of tillage. The distance over which soil is translocated is important as it affects the distance over which soil constituents (amendments and contaminants) are dispersed, or mixed, by tillage.

Figure 1. Simple illustration of soil translocation by tillage. Initial position of soil volume is red and final position is blue. = forward translocation, = lateral translocation, WT = unit width of tillage.