The role of organic matter in the maintenance of site productivity on sandy soils.

A comprenensive research programme is being undertaken in south-west Victoria to study the productivity of successive crops of radiata pine planted on infertile sandy soils low in organic matter. The research has concentrated first on identifying the important edaphic and environmental factors regulating growth in this locality and, secondly, on the effects of management practices on these factors. Results have been used to establish principles which need to be followed in order to maintain site productivity for radiata pine monoculfures growing on such soils in low-rainfall regions. It has been shown that litter and logging residue remaining after clearfelling should not be burnt but left on-site so as to conserve organic matter and nutrients (especially nitrogen). The residue also acts as a surface mulch to conserve soil moisture.