Introduction

The art and study of plant nutrition go back at least to Roman times, as essential parts of the business of producing food. This long historical perspective can usefully be studied now, when plant nutrition is largely a matter of science in its principles, but still, to a surprising extent, an art in its application, even in developed countries. In the past, the delay between a scientific advance and the application in practical agriculture was usually many decades. Thus, the rates of fertilizer used by Lawes (Johnston 1994) in experiments in 1850 were not applied widely in practice until after 1950. The movement to precision agriculture may now take the final step to a full science-based nutrition of plants in the field. For these reasons, we have thought it worthwhile to give a highly condensed outline of the history of scientific advance in our subject. It is now generally accepted that under given growth conditions, uptake of a solute by roots is related to its concentration in the soil solution and the extent to which this, in turn, is buffered by the soil. Though these apparently simple ideas were advanced more than a century and a half ago, only recently have they been defined clearly enough to form a basis for detailed understanding of the effect of solutes on plants grown in the soil. These ideas have, in particular, been obscured by specific effects of roots with their associated rhizosphere organisms: for roots not only vary widely in their response to solute concentration, but also alter near them the soil properties we measure in the bulk of the soil. Thus, it is only since the 1950s that we have come within reach of the objective clearly set us by Liebig in 1840 when he wrote: ‘A rational system of agriculture must be based on an exact acquaintance with the means of nutrition of vegetables, and with the influence of soils and action of manure upon them’. The history of ideas about soil and plant relations has been well described by Russell (1937) and Wild (1988) for the period up to the beginning of the twentieth century.