Express-diagnostics method for assessment of soil compaction for different cultivation methods

Soil compaction remains a concern because of the heavy tractors used in intensive agriculture. When axle loads of vehicles increase, soil compaction is affected in deeper soil layers. An efficient tool is needed to assess the impact of machines on soil. Therefore, an express-diagnostics method was developed and implemented under Estonian agricultural conditions. Since 1976, an investigation has been carried out on how wheeled or tracked vehicles (WTV) influence soil under agricultural conditions in Estonia. The main goal of the investigation was to develop a mathematical model and a corresponding computer simulation system. Uncompacted and compacted soil was modelled using a vegetation model of "guttated vegetation miniatures". The system allows soil vulnerability to compaction to be assessed by the criterion (qabc) agro-empirical bearing capacity (ABC). Both field and laboratory data were used in the development of the system. We have found that at the deepest layer the bulk density was higher for tilled soil compared to no-tilled soil. Dry soil bulk density in no-tilled soil after 2 years in the deepest layer was 0.11 Mg m3 –1 less than tilled soil, and for no-tilled soil after 3 years in the deepest layer, it was 0.12 Mg m3 –1 less compared to the tilled field soil. The amount of agronomically preferable aggregates (2–4.75mm) was major in tilled soil compared to no-tilled soil. It means that the preferred (in an agronomical sense) soil particles Kstr in conventionally tilled (ploughing – K2; K3) fields were significantly better compared to no-tilled (O2; O3) fields in the trial plots. These results emphasize the benefits of multifunctional modelling systems (computer simulation and simulation by vegetation miniatures) and the need to improve assessment of methodology for receiving adequate and probable results, and finally for yield prediction.