THE ENERGY EFFICIENCY OF SEEDBED PREPARATION FOLLOWING MOLDBOARD PLOWING

Field experiments were conducted for a period of four years beginning in 1987, to determine the efficiency with which a range of cultivation implements could produce a seedbed for combinable crops following mou ldboard ploughing. Four sites were used, ranging from clays (Calcareou s Gleysols (F.A.O., 1988. Soil map of the world, 1:5 000 000, Revised Legend. World Soil Resources Report No. 60, Rome) to a sandy clay loam (Orthic Luvisol (F.A.O., 1988)), Laboratory experiments were also con ducted on samples of the field soils and both field and laboratory mea sures of the energy to produce a given tilth were compared. Results in dicated that less aggressive implements, such as soil driven harrows o r spring-tine cultivators, were often capable of producing seedbeds eq ual in quality to those of powered machines with similar or improved e fficiency, but with more passes across the field. Impact and cutting o f soil aggregates in laboratory tests suggested that significant impro vements to field machine can be made.