Elements of design and evaluation of animal-drawn weeders

The influence of soil parameters and weeder design on implement performance is discussed. Soil parameters that are important in this context are cohesion, adhesion and internal friction. Important weeder design parameters are blade angles of attack and approach, blade overlap and blade support configuration. An example of an animal-drawn weeder developed in Mexico is analysed. An evaluation of weeder performance will depend on the categories of information required for a particular purpose and should include both technical and socio-economic parameters. Evaluation parameters discussed are: soil type and condition; crop and weed type and population; effectiveness of weed control; crop damage; implement draft, forward speed and power requirement; working width and speed; theoretical and actual field capacity, field efficiency; durability; ergonomic and economic appraisals.