His PhD thesis, completed at Cornell University in 1931 and entitled Capillary conduction of liquids through porous mediums,[3] was arguably one of the best known in the field of soil physics.
His thesis represented the first decisive progress beyond the work of Edgar Buckingham in the extension of Darcy's law to describe water movement in unsaturated soils.
Early in his career, Richards recognised the importance of capillary potential to plant-soil relations, and described the principles, construction and operation of the tensiometer.
Although Richards claimed the primary purpose of the apparatus was the extraction of soil solution for salinity analysis, he also pointed out its potential for application to energy studies.
He developed much of the modern apparatus and methodology used for study of soil water, hence playing a pivotal role in the transformation of knowledge on this subject from the qualitative stage to one based on measurements and mathematics.