Learning from the soil biophysics pioneers

Soil biophysics may be a relatively new term, but research on biological and physical interactions in soil dates back over a century. As we embark on new research today, blessed with a plethora of techniques and computing power that would be fanciful to the pioneers of the discipline, we have plenty to learn from the past. Devoid of techniques to drive their research, the pioneers focussed on big scientific questions, creating new techniques when none were available.

One of the earliest soil biophysics papers was published by Haines in 1923.  He measured soil volume changes with moisture content extremely accurately in arguably the first controlled study exploring biological polymer (gelatine) impacts to soil. He concluded that ‘By means of the method the effect of alternate wetting and drying of soil in producing good tilth is illustrated.’  This early work focussed on volume changes, a major biophysical process driving soil structure formation and stabilisation that much present research ignores.  While modern research excels at visualizing 3D soil structure (e.g., X-ray CT) and quantifying aggregate stability, it frequently falls short in elucidating the underlying mechanisms. Soil aggregate pioneers like Hénin (1940s) and Monnier (1965) went beyond descriptive analyses, delving into the physics of particle interactions (cohesion, contact angles) to understand the factors governing aggregate stability.

It is time for soil biophysicists to get back to basics, taking inspiration from the ingenuity and inquisitiveness of overlooked papers of their predecessors. With more effort placed on HOW soil biophysics drives structure formation, and less effort on correlating WHAT we see, progress would be less incremental. We have an array of exciting new tools at our disposal, but these need to be used beyond visualisation and correlation to make leaps rather than small steps in understanding.

Haines, W. 1923. The volume-changes associated with variations of water content in soil. Journal of Agricultural Science, 13, 296-310.

Hénin, S. 1943. The influence of imbibition of various liquids on the resistance to disintegration of earthy agglomerations in water. Comptes Rendus Hebdomadaires des Seances de l’Academie Des Sciences, 217, 578-580.

Monnier, G. 1965. Action des matieres organiques sur la stabilite structurale des sols. Annales Agronomiques, 16,471-+.