WASTES IN RELATION TO AGRICULTURE AND FORESTRY 



93 



control practices and means for predicting the 

 extent and probability of duststorms, the potential 

 for improvement in understanding, control, and 

 prediction remains high. 



New research must include further study of 

 the wind erosion processes and the definition of 

 principles to form a scientific basis for design of 

 more effective control practices such that the pro- 

 ductivity of farmlands will be preserved and pol- 

 lution of the atmosphere reduced or prevented. 

 The studies must consider various concepts for 

 describing and delineating the influence of atmos- 

 pheric wind and turbulence on soil detachment and 

 transport; the effect of wind and related atmos- 

 pheric factors on soil drying and creation of soil 

 surface conditions susceptible to high rates of 

 detachment; the modification of tillage practices 

 and machines to provide effective and lasting crop 

 residues and soil cloddiness conditions to resist 

 soil detachment; the theory of barriers, their 

 effect on the microclimate, and optimum design 

 and orientation based on analysis of wind factors 

 and probabilities ; the use of chemicals and petro- 

 leum-derived soil stabilants as a part of control 

 systems; the tolerance of crop plants to abrasion 

 for windblown soil particles ; the development and 

 selection of better strains and varieties of grasses 

 and crops to tie down soils susceptible to blow- 

 ing; improved prediction equations for flow con- 

 ditions; and interrelations of soil erosion rates, 

 dust deposition, soil properties, soil treatments, 

 environmental pollution, and soil renewal. 



Windbreaks 



Land in the Great Plains is almost constantly 

 exposed to the damaging action of winds. "Winter 

 gales remove the snow from open fields on the bare 

 soil ; plants become sparse and are sometimes win- 

 ter-killed. During dry springs and summers, soil 

 blowing and erosion damage from high winds is 

 greatly increased. Strips of trees (windbreaks and 

 shelterbelts) across open areas are a powerful 

 means of amelioration, influencing not only the 

 immediate site but also remoter areas. Crop pro- 

 duction is increased by the conservation of soil 

 and soil moisture, and livestock are afforded pro- 

 tection in shelterbelts. Living conditions are im- 

 proved not only through beautification of the 

 homesteads, but by reduced fuel costs. 



Cover is effective in reducing soil movement by 

 wind. Where grasses thin out or disappear due to 



drought, cultivation, or overgrazing, vast dust- 

 storms may result. Brush invades when grass dis- 

 appears. Grasses stabilize sand dunes, ditchbanks, 

 and roadbanks. 



To fulfill the many needs for protective belts 

 of trees and other vegetation, expanded research 

 must focus on the development or selection of 

 suitable species. A wide array of species of trees 

 and shrubs will need to be evaluated to meet the 

 diverse needs of varying climatic conditions. 

 Other needed research information includes that 

 on optimum depth and spacing of plantings ; cul- 

 tural practices to maintain vigor, density, and 

 longevity of plantings ; disease and insect control ; 

 and the effect of the vegetation on wind movement. 



Feedlots 



Large feedlots are now under criticism for the 

 dust nuisance they create. These dusts are not only 

 a nuisance to the housewife but of serious concern 

 to those with dust allergies. It is also suspected 

 that dust in these feedlots reduces efficiency of 

 weight gain. Sprinkling is one technique that has 

 been used with some success. However, further 

 study of the problem is needed to develop alter- 

 nate methods and more economical sprinkling 

 techniques. 



Where dusts arise from feed grinding, mixing, 

 and handling, techniques for pneumatic convey- 

 ing and use of cyclones — mechanical devices to 

 remove dusts from air — offer a means for control- 

 ling dust. Cyclones, when properly used, can ap- 

 proach efficiencies very near 100 percent removal. 

 When not properly used, however, their efficiency 

 is very low. Cyclones are presently designed pri- 

 marily on a trial-and-error basis so that they 

 usually only apply to the special set of circum- 

 stances for which they were developed. Research 

 is needed to develop the methodology for the 

 rational design of cyclones so that they can be 

 utilized for control of dusts. 



The relationship of weather conditions ro dust 

 problems is recognized but needs much further 

 study. 



Cotton Gin Dusts 



Under average conditions, about 1.000 pounds 

 of trash accrue with each bale of cotton ginned. 

 Some of this is disseminated into the atn* 3] 

 as very tine dust. In addition to its plainly irritat- 

 ing effects, it is adverse to the respiratory health 

 cf people miles to the leeward of the gin. Burn 



