What might explain the long development and rapid decline of agriculture on blackland in the west of Scotland?  what accounts for nearly simultaneous change on a large scale?  Was there some large natural failure? war? technology?  As a system of small tenant farmers on marginal land far from the centres of power, crofters were not in a position to influence policies that affected their livelihood.  By widening the focus from measurable soil conditions to ways in which a system fine-tuned to its environment was affected by decisions taken in the larger society,  we can begin to see how distant changes can unleash a cascade of effects down through farms and families into the very capability of the soil itself.

Complex systems such as agriculture can best be understood at a number of levels, from the most general to the most specific.  Events or changes at high levels cascade through lower ones with strong local effects.  For example, invention of the tractor ultimately affected soil structure and functionality; availability of birth control affected available labour and hence, management.

Based on these observations, the following table was constructed, showing the cascade of large-scale societal changes:

	Level I    Context provides the broad societal background into which local development occurs, and includes climate/disasters, historical events such as war, and technological changes ranging from the internal combustion engine to birth control. Coastal storm photograph by Owen Humphreys
	Level II   Landscape includes factors affecting regional land use such as population, traditional management and livestock techniques, law, and local economic conditions.
	Level III   Field is the local management level at which factors such as topography, drainage, vegetation, cropping preferences, family structure/manpower affect land use within an agricultural unit, farm or croft.
	Level IV   Soil provides a general description as easily observable within 1m from the surface, such as structure, hydrology,  horizons, with the spade or auger as a tool.
	Level V   Subsurface inspection requires laboratory techniques such as pollen analysis to determine genesis, microbiology and molecular/chemical states.

Such a multi-disciplinary investigation has both advantages and disadvantages.  It is a way of avoiding a reductionist view, and missing ‘things which are hidden, easily overlooked, or forgotten’ (B. Ball, 2015), and which might provide an essential key.  Local knowledge suggests that the complex system which we call blackland cannot be understood through such single topics as crop rotation or soil structure, because the interdependence of people, stock, wildlife and land is essential to its management.   Disadvantages include the raising of many more questions than can be answered within a few years, leaving much for future investigation. The statistician Tukey observed ‘finding the question is often more important than finding the answer’ (quoted in Yoccoz, 1991).