Date of Award
Master of Science
Plant, Soil and Environmental Sciences
Frank F. Bell
George J. Buntley, Charles R. Graves
The purpose of this study was to determine the average and potential yields of certain crops on various soil mapping units in Tennessee and to relate these yields to the physical and chemical properties of these soils where possible. The average yields as determined by this study may be used as a guide in updating the yield estimates of the various soil mapping units in Tennessee.
Yield data for full and medium-season corn, grain sorghum, soybeans, wheat, oats, barley, and cotton were obtained from variety trials at various locations. The five highest yielding varieties for a given year were used and referred to as yearly average for a specific crop. These yearly averages, in turn, were used to obtain a long-term average for a given soil and referred to as average yield.
Standard deviations and coefficients of variation for each crop's yield on the various soils were calculated. The soils were then indexed in relation to the highest yielding soil and the differences in yields were related to soil differences.
Com yield data were compiled from a production field study from 1957 through 1971 at the West Tennessee Agricultural Experiment Station, Jackson, Tennessee.
Potential and average soil yields were determined and indexed for comparison in the same manner as they were for the variety trial data. Where yields of different soil mapping units of a given soil were available for the same years, these soil mapping units were also compared.
Cotton yield data were selected for several counties in Tennessee from the Cotton Emphasis Program for a 3 year period. Average yields, standard deviations, and coefficients of variation were determined using the varieties common to most soils and all varieties grown on each soil.
Yields of the different soils from the various data sources were compared and related to differences in each soil's characteristics.
Differences in soils' yields can often be explained by the differences in depth, water-supplying capacity, degree of erosion, slope or some combination of these factors. Average yields and potential yields of soils varied with the crop used to make the estimate.
Carpenter, Harold Franklin, "Average and potential yields of different crops on certain soils of Tennessee. " Master's Thesis, University of Tennessee, 1973.