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Yields from Bt and herbicide-tolerant seed technologies used in corn, soybean, and cotton production compared to all other seed technologies, by region, 1996-1998

Technology/Region	1996	1997	19982
	Percent Difference1
Bt Corn
Heartland	4.6	-1.6	5.7*
Northern Crescent	id	id	16.4
Praire Gateway	id	id	30*
Herbicide-tolerant corn3
Heartland	-1.5	-10.2	5
Northern Crescent	id	id	25.2
Praire Gateway	id	id	-10.1
Herbicide-tolerant soybeans
Heartland	-2.4	13.6**	4.4
Mississippi Portal	2.8	-6.2	-3.6
Northern Crescent	id	-4.6	4.8
Praire Gateway	id	21.0**	24.2
Southern Seabord	id	13.3*	21.4*
Eastern Uplands	id	id	-8
Bt Cotton
Mississippi Portal	8.6*	0.6	15*
Southern Seabord	id	19.6**	-0.3
Fruitful Rim	id	4.2	26.1**
Herbicide-tolerant cotton
Mississippi Portal	id	-4.8	-7.9
Southern Seabord	id	-11.9*	18.5
Praire Gateway	id	id	id

¹ Percent difference between the yield of Bt or herbicide-tolerant seed technologiew and all other seed technologies. Differences were statistically compared using a difference of means tests. All other seed technologies include acreage planted to all other purchased and homegrown seed. Differences between the mean estimates cannot necessarily be attributed to the use of the seed technology since they are influenced by several other factors not controlled for, including irrigation, weather, soils, nutrient and other pest management practices, other cropping practices, operating management, etc.
² 1998 estimates for corn and cotton include acreage and production with stacked varieties (with Bt and herbicide- tolerant genes).
³ Includes seed obtained by traditional breeding but developed using biotechnology techniques that helped to identify the herbicide-tolerant genes.
id=insufficient data for a statistically reliable estimate.
** significantly different from all other at the 5 percent level.
* significantly different from all other at the 10 percent level.
Source: USDA