Laboratory investigation of cutting forces and soil disturbance resulting from different manure incorporation tools in a loamy sand soil

Injection of manure is becoming more popular than surface spreading due to its agronomical and environmental benefits. In this study, four different existing tools (two sweep types and two disc types) for liquid manure incorporation were tested in an indoor soil bin located in the Department of Biosystems Engineering at the University of Manitoba with loamy sand, to investigate the effects of working depth (50, 100 and 150 mm) and speed (0.57 and 1.4 m/s) on soil cutting forces and soil disturbance. Draft forces and soil disturbance for all tools significantly increased with working depth, but not with working speed. Owing to its wider soil cutting width, sweep B required 80% more draft force than sweep A. For the same reason, sweep B disturbed a 44% wider soil surface along the tool passage, compared to sweep A. On the average, sweep type tools created 27% new soil pores, which would be available for containing injected manure. For the discs, vertical forces decreased with increased working depth. As compared with disc A, wider surface disturbances along the tool passage were observed for disc B due to its two concave disc design. Comparing soil disturbance for different depths, disc B may not be suitable for manure incorporation at shallow depths (50 and 100 mm). At greater depths (150 mm) both disc-type tools will favor manure coverage.