The development of techniques for assessing compactibility of field soils.

摘要

During the last five decades, effects of soil compaction on crop growth and yield havebeen of increasing concern due to the introduction of heavier agricultural machinery.Most researchers agree that, although a certain degree of compaction can be beneficialto crops, loading beyond this can be very detrimental and, therefore, soil compactionshould be considered as an important factor which should be managed in cropproduction systems. The majority of work to date has been conducted using disturbedsoil samples and hence not representative of field situations.The aim of this project was to investigate further the compactibility behaviour of fieldsoils. Work was conducted in a soil bin as well as on field soils (sandy loam and clay )in a range of climatic conditions. Techniques for assessing soil compactibility areproposed, based on the stress-strain (load-sinkage) characteristics of soil, soil strengthprior to loading, and the mode and extent of soil deformation for a given loadingsituation. The determination of these soil characteristics proved somewhatcumbersome and time consuming and, therefore, the prediction of these variables frommore easily determined soil properties (volumetric water content, initial dry bulkdensity, void ratio and degree of saturation) was investigated with promising results.In addition, a model is proposed which predicts the extent of deformation within thesoil profile for a given loading situation.