Mechanical behaviour of agricultural soils

Abstract The Cambridge theory of critical state soil mechanics deals with the mechanical behaviour of saturated soils and postulates methods for predicting the changes in soil pore space in response to applied stresses. This analysis is very relevant to the study of compaction and cultivation problems in agriculture. The paper presents a greatly simplified version of the critical state theory devoid of all the mathematical complexities of plasticity theory and deals with some of the problems associated with its adaptation to partly-saturated soils encountered in agricultural practice. Methods of fracture mechanics and the much neglected analysis of the mechanical behaviour of soils with moderate tensile strength have been incorporated into the unified hypothesis proposed. Some simple field examples are analysed and a generalized extension of the theory to cope with soil moisture changes is presented.