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United States Department of Agriculture

Agricultural Research Service

Title: Factors Related to Dryland Grain Sorghum Yield Increases, 1939 Through 1997

Authors
item Unger, Paul
item Baumhardt, Roland

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 13, 1999
Publication Date: N/A

Interpretive Summary: Research involving dryland grain sorghum has been conducted at the USDA-Agricultural Research Service, Conservation and Production Research Laboratory, Bushland, Texas, since 1939. For this study, grain yield data was obtained from 37 studies conducted at the Laboratory, which provided 502 treatment-years of data. An examination of the data showed that grain yields more than tripled during the 1939 to 1997 period. Our objective wa to show which factors were mainly responsible for the yield increase. Factors evaluated were annual precipitation, growing season rainfall, soil water content at planting, soil water use during the growing season, growing season evapotranspiration (evaporation and transpiration), and year of record. Using the entire data set, it was found that grain yields increased an average of about 50 kg ha**-1 (45 pounds per acre) per year. During the 1956 to 1997 period when the entire data set was more complete, the results showed that yields increased 139%, with 46 of those percentage units resulting from use of improved hybrids, based on results of a uniformly managed 40-year study. The remaining increase of 93 percentage units resulted mainly from increased soil water contents at planting time. The increases in soil water contents at planting resulted from changes in management practices with time, with the adoption of improved crop residue management practices after about 1970 being the main reason for the greater soil water contents at planting. Results of this study show the importance of maintaining crop residues on the soil surface through the use of conservation tillage practices (for example, no-tillage or reduced tillage) for obtaining good yields of dryland grain sorghum.

Technical Abstract: Grain yields of dryland (non-irrigated) grain sorghum [Sorghum bicolor (L.) Moench], a major crop in the southern Great Plains, more than tripled in studies at the USDA-Agricultural Research Service, Conservation and Production Research Laboratory, Bushland, Texas, during the 1939 to 1997 period. Our objective was to determine factors primarily responsible for the yield increase. Factors evaluated were annual precipitation (ANPRCP), growing season rainfall (GSPRCP), soil water content at planting (SWPLNT), soil water use (SWUSE), growing season evapotranspiration (GSET = GSPRCP + SWUSE), and year of record (YEAR). For the report, we assembled 502 treatment-years of grain yield data from 37 studies. For the 1939 to 1997 period, grain yields increased about 50 kg ha**-1 annually. Yields increased 139% during the 1956 to 1997 period, with 46 of those percentage units resulting from use of improved hybrids, based on results of a uniformly managed 40-year study. The remaining 93 percentage units were attributed to other factors, primarily to SWPLNT. Increases in SWPLNT resulted from changes in management practices with time, mainly the adoption of improved crop residue management practices after about 1970.

Last Modified: 7/22/2014
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