The tree phase may also allow the management of herbicide resistant agricultural weeds, an issue of particular importance in Australian dryland farming sytems. The most likely deleterious effects will come from the production of surface debris following tree harvesting. Although smaller debris may contribute to the soil reserves of recalcitrant organic carbon, the larger debris may interfere with agricultural practice. Breakdown products of this material may be toxic to plants. Some potential PFT products, such as bioenergy, may result in the total removal of tree material and debris will not be an issue.
Any nutrient depletion associated with the tree phase is considered manageable.
An issue that needs practical resolution is the removal of stumps on harvest. The economic analysis did not bring into account the likely land conservation benefits of the PFT system such as reducing the loss of land to salinity and the reduction in off-site impacts such as the loss of natural flora, wildlife habitat, water resource quality and rural infrastructure. We suggest that if market based assessments are to be made of technical solutions to natural resource problems a framework should be used that brings the value of the natural resource base and other off-site effects to account. Developing such a framework is a priority for research. Despite its current marginal economic status, we suggest that the PFT system provides a feasible technical solution to reducing the rate of salinization associated with agriculture in drier areas.