Electron Probe Microanalytical Studies of Phosphorus Distribution within Soil Fabric

Electron probe microanalysis has been used to follow the distribution of phosphorus and associated elements within soil features to establish the composition of the immediate root environment. Various qualitative analytical modes of using the instrument are described involving either specimen traverse or spectrometer scanning with a static beam, line scanning, one‐dimensional scanning, area scanning, or successive rast counting. By these means phosphorus has been found to occur variously as discrete grains of rare‐earth phosphates, in preferential association with iron in iron/manganese concretions, as concentrations within undifferentiated soil matrix and ferrans at void surfaces, and to be associated with calcium in a fresh root and possibly with iron rather than calcium, aluminium, or potassium in an old root.