Wind erosion, which removes fine particles from agricultural soils, may reduce productivity of the eroded soil by eliminating essential nutrients normally attached to these particles. The ability of the soil to hold water in the root zone is also impaired with the loss of fine particles.
Thirty to 41 consecutive years of rainfall and yield data for dryland cotton, sorghum, and kafir were analyzed by the use of multiple regression techniques to determine the yield trend when the effect of rainfall was removed. The results suggested that the crop yields became lower the longer the soils were cultivated. The correlation coefficients between yield and time were not significant for most crops and locations, but the negative regression coefficients suggested that soil productivity was lowered.
Sorghum yields at Dalhart, Texas, were calculated to have been reduced 63% in the 1908 to 1938 period by using estimated wind erosion data (Lyles, 1975) and yield reduction-soil loss data (Eck and others, 1965). The multiple regression method used in this report revealed that sorghum yields for the same period decreased 67%. The yield decrease could have resulted from annual cropping, wind and water erosion, or increased hazards such as insects or soil-borne diseases. During the periods when data were available, improvements in crop varieties and cultural practices should have partially compensated for any decrease in soil productivity due to continuous cropping, but these analyses suggest that improvements did not keep pace with the factors responsible for decreased crop production.
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