The physical distribution of mineral material on forage plant cell walls

Data are advanced to show that controlled ashing of plant cell wall material at 500°C for 3 hr provides a convenient method of removing organic matter and permits visual study of mineral material within the plant structure. Evaluation of a range of mature tropical and temperate grass and legume forage species with the scanning electron microscope has shown the existence of a mineralized component over the cell walls. This component is distributed in sheets of thickness varying upwards from c. 0.1 µm and is located on the outer surface of cell walls, possibly constituting a masking layer around digestible organic material of the cell wall. Energy-dispersive X-ray analysis shows the major elements constituting this mineral layer to be phosphorus, calcium, sulphur and potassium.