Degree Type


Date of Award


Degree Name

Doctor of Philosophy




The vast rangeland areas of the nation are becoming increasingly valuable to society. Economic progress, changes in society's needs, and varying roles among regions are influencing the relative importance of the nation's rangeland uses, its products and the environment. The general public has become concerned over range grazing and its associated environmental effects. This study analyzes the relationship of grazing to the soil erosion rate and the modifying effect of vegetation on this relationship. It also examines the interaction between the grazing sector and crop sector in the production of livestock feed;The linear programming model used in this study is national in scope, incorporating 28 market regions, 105 producing areas, and 106 potential natural plant communities (based on natural vegetation). This model is used to examine three solutions for the year 2000. The Base is an unconstrained soil loss solution and it is compared to the other two solutions. Once the Base is attained, producing area soil loss is restricted to 2T('1) and T('1) levels;The national and regional responses to the changing soil loss^levels are examined. Total land (including grazing land) used to^meet the projected demand levels declines as the allowed soil loss^declines, but irrigated cropland increases. Changes in range^management strategies are examined. The changes in the land^use, costs of production and transportation, investment cost on^rangeland, per unit cost of selected outputs are also examined.^The impacts of the soil loss reduction on yields and regional^distribution of production are analyzed. As the allowed soil loss^decreases, grazing management shifts from higher intensivestrategies to less intensive strategy in a region where acreagesgrazed are erosive and less productive. The study indicates thatthe agricultural industry as a whole and the society will gain long-;run benefits if soil loss is restricted;('1)T indicates Soil Loss Tolerance limit that allows the maximum rateof soil erosion without reducing the productivity of a given area.



Digital Repository @ Iowa State University,

Copyright Owner

Pradeep Kumar Sircar



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159 pages