An assessment of the effects of road dust on agricultural production systems

Abstract

It has been proposed that the dust drifting on to farmland adjacent to unsealed roads can reduce the volume and value of agricultural production from that land. The objective of this report is to describe an investigation into this proposal. A recent requirement of the National Roads Board is that all funding applications for roading improvement works must be ranked for priority on the basis of cost-benefit analyses. This exploratory study attempts to place a value on a previously unquantified benefit from sealing roads; increased returns from agriculture and horticulture due to road dust removal. Because of time and resource constraints, all information used in the report was gained indirectly, through a host of other partially related studies and in consultation with a wide range of technical and agricultural experts. Hence, due to the uncertainty surrounding many of the assumptions used, all results of the study are expressed as a range of possibilities. Chapter three outlines all possible physical effects of road dust on production systems along unsealed roads. The most significant of these include: reduced photosynthesis leading to loss of plant yield; increased pest and disease incidence causing yield losses and reduced quality of horticultural produce; hindered pollination, especially in small seeded fruits; animal health problems (e.g. ovine pneumonia and pinkeye). Chapters four, five and six confront the factors affecting the generation and distribution of road dust and develop a model to predict the physical production losses. Chapter seven quantifies the enterprise types and Chapter eight usage in roading economics. range of relates the costs to a number of findings to practical The report concludes that high value, intensively grown horticultural crops suffer the greatest costs from road dust and that road dust damage through such areas may, in part at least, justify road sealing programmes. Certainly, further research into the subject is warranted.