WASTES IX RELATION TO AGRICULTURE AND FORESTRY 



carbons annually. In nearby areas, these hydro- 

 carbons can become more serious by being con- 

 verted to photochemical toxicants. 



During the past 20 years, considerable research 

 has been underway on (a) evaluating the relative 

 sensitivity of different kinds of economic plants, 

 trees, and livestock to various levels of specific 

 air pollutants; (b) determining the actual com- 

 ponents in polluted air that cause damage; (c) 

 measuring the acute and chronic effects of given 

 levels of specified pollutants in different plants 

 and animals; (d) developing management prac- 

 tices that would minimize or ameliorate the ad- 

 verse effects of given air pollutants; and (e) de- 

 veloping and selecting varieties of crops and trees 

 with higher tolerance to air pollutants. Very prom- 

 ising research is underway towards prediction and 

 abatement of forest fires due to electrical storms. 



In meeting the problems inherent in the dam- 

 ages of airborne toxicants to agriculture and for- 

 estry, it would be most advantageous if these 

 chemical effluvia could be eliminated at the source. 

 Some accomplishment has been attained on this 

 objective — for example, virtual discontinuance of 

 sulfur dioxide emanation from the smelters in 

 Trail, British Columbia, Canada — and more cer- 

 tainly will be accomplished. But there is little hope 

 that this approach will adequately cope with the 

 growing problems of air pollutants in agriculture 

 and forestry. 



There is an urgent need to improve the validity 

 of the techniques available for assessing damages 

 from air toxicants. Information is particularly 

 weak for assessing chronic damages. 



Little is known of the actual physiological 

 mechanisms by which the harmful effects of air 

 toxicants take place. Ignorance on these funda- 

 mental problems is a roadblock to valid under- 

 standing of damages and possible counter- 

 measures. 



One of the most promising avenues for attain- 

 ing countermeasures to air toxicants is that of 

 developing and selecting species, varieties, and 

 genetic lines of crops, ornamentals, and trees that 

 are tolerant, if not immune, to the major effects 

 of chemical air contaminants. 



There is evidence that expansive areas of vege- 

 tation, particularly woods, have a cleansing action 

 on toxic wastes in the air. Much more information 

 is needed on this effect. 



The possibility of developing chemical protect- 

 ants against air pollution damage needs much 

 further exploration and study. 



Even though total contribution to air contami- 

 nation from forest fires seems relatively small, 

 the total damages from these fires go far beyond 

 their contribution to air pollution. All possible 

 effort to develop better technology and better in- 

 formation to curb such fires should be pursued. 



In view of the magnitude of the growing prob- 

 lems, and the paucity of research effort on air 

 toxicants by agriculture and forestry in the past, 

 it is urgent that research effort on the problems in 

 this general area be expanded and pursued with- 

 out delay. 



Airborne Dusts 



During the average year, 30 million tons of 

 natural dusts enter the atmosphere. Most of this 

 arises as soil blowing from inadequately pro- 

 tected fields under cultivation, deteriorated range- 

 lands, and sand dune areas. A small amount arise- 

 from highway and industrial construction sites. 

 Susceptibility to wind erosion is the dominant 

 problem on 55 million acres of cropland in the 

 United States. 



Industries such as cotton ginning, alfalfa mills, 

 lime kilns, cement plants, smelters, and mining 

 operations release 17 million tons of dust into the 

 atmosphere annually. This dust often coats the 

 foliage of nearby crops, ornamentals, and trees. 

 Growth and quality of product may be impaired. 



Windblown soil not only robs the land of good 

 topsoil, it also becomes a serious air pollutant. 

 Inspiratory ailments of man and animals are ac- 

 centuated. Eyes are afflicted. Highway and air 

 vision is impaired. Machinery is scourged by paint 

 removal and dirt in bearings. Offices, home-. 

 schoolrooms, and factories are completely perine- 

 al ed by dust. Pesticides may be carried long dis- 

 tances. Farmstead-, fence rows, ditches, and roads 

 may be partially buried by drifts of dust. 



Wind erosion research and its application has 

 contributed importantly to the effectiveness of 

 today's conservation and other advanced fanning 

 methods in reducing the threat of future '"Dust 

 Bowls" in the Great Plains. Meteorological rec- 

 ords show that the drought in Kansas during the 

 mid-lOoO's was just as bad as that during the 

 1930's. Yet records show that soil blow ing was 



