Soil fragmentation and the efficiency of tillage implements

In field experiments conducted over a period of 6 years, seedbed preparation was carried out on four different sites with clay contents of 45, 27, 24 and 15%. Over the years soil conditions varied considerably. Seedbed preparation was conducted in the spring with implements of different designs such as drags and harrows, twin rotor, gyro- and rotaspikes. lysing the fragmentation due to tillage, the soils could be grouped according to moisture contents and soil compaction. Soil with a moisture content greater than 0.20 kg kg−1 was classified as wet soil irrespective of the state of compactness. Soil with a lower moisture content was classified as moist soil and divided into the following compactness states: loosened, workable and compacted. Loosened soil was ploughed or chiselled just before seedbed preparation, workable soil was autumn ploughed and compacted soil was unploughed. alisation procedure transforming the fragmentation effect and the specific energy supply to dimensionless quantities eliminated the difference between all the unloosened soil states, i.e. states where the soil was a continuous compact material. This normalisation procedure related the increase in aggregate surface area to the initial surface area. The specific energy supply was related to the specific energy needed to fracture a clod or to fracture the soil in the ground with a bevameter. With this normalisation procedure the fragmentation effect of the three compact states—workable, compacted and wet soils—was described by the same function. Loosened soil was, however, still different and had a much lower effective fragmentation than the other states. In general, the strength of the clods determined the fragmentation in this soil state. rmalisation procedure provided a basis for an investigation of the energy efficiency of fragmentation of various tillage implements and tools. For the compact soil states, drags were superior in fragmentation compared to harrows and rotary implements (∗∗P<0.01). There was no difference in fragmentation between harrows and rotary fragmentation implements. e loosened soil state, there was no significant difference between the three implement groups. Rotary implements seemed, however, to be more effective in the conversion of energy to fragmentation.