Comparison of Yield Potential and Herbicide Program Cost Between Herbicide‐Resistant and Conventional Soybean

Abstract

Using the results of seventy‐one soybean (Glycine max) variety performance trials, the existence of a yield drag (YD) of herbicide‐resistant varieties when compared to conventional varieties is verified. The trials were conducted from 1996 to 2000 at five locations, on 569 varieties covering three maturity groups in irrigated and dryland conditions using conventional tillage. Trend analysis of YD suggests that it (i) is magnified by irrigation; (ii) has declined to negligible levels; (iii) is not significantly different across maturity group; and (iv) exhibits some locational differences. An analysis of six herbicide programs revealed that glyphosate programs are generally more expensive than reduced‐rate conventional programs but are comparable to or cheaper than full‐rate conventional herbicide regimes. It is further conjectured that seed/technology and herbicide cost differences across seed/herbicide systems will adjust to competitive conditions in the long run.

Acknowledgments

The authors wish to acknowledge the Arkansas Soybean Promotion Board for financial support; the staff of the Northeast Research and Extension Center and the Southeast Research and Extension Center. Special thanks also go to Debra Ahrent and Ira Eldridge, Diana Danforth, and Jennifer Lafferty.

Notes

^aThe 75% adoption rate is based on an informal survey of Arkansas seed dealers—∼85% of all seed sales were glyphosate‐tolerant varieties with the difference between seed sales and planted acreage being bin run or farmer saved seed.