3rd quarter 2004

Transgenic soya - why so successful?

More than 55% of the world's soybean acreage is used to grow transgenic, mostly herbicide-tolerant varieties; in the USA the proportion is 85% and in Argentina it is as high as 95%. By comparison, transgenic corn has a share of 11% of the global corn acreage and a share of 40% in the USA. Why are transgenic soybeans so successful?

The transfer of a herbicide-tolerance gene allows soybeans to withstand the use of broadband or total herbicides, whereas weeds are reliably eliminated, which greatly facilitates weed control. Instead of spraying fields several times, one application is generally sufficient - thus saving labour, machinery and resources.

With postemergence spraying, prophylactic spray treatment is no longer necessary, and this gives the farmer more flexibility. Broadband herbicides are quickly broken down, and their effectiveness means that soil processing can be simplified. All in all, the environment also profits. Despite a technology fee, the planting of herbicide-tolerant soybeans is an attractive proposition for farmers.

Research in the USA on the use of herbicides from 1996 to 2003 shows that the rate of herbicide applied (active substance per area unit) in the case of transgenic soybeans is now higher than with conventional soybeans. Two to three applications are necessary in addition to other herbicides in order to deal with resistance and changes in weed population.

Furthermore, transgenic soybeans have lower yields on average (from -12% to +5%), which could possibly be connected with inhibited nitrogen fixation during droughts and a proneness to disease. Overall, there were major regional variations in the results.