Hope Not Hype - Third World Network

Yield
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hybrids had similar to or lower total N content in grain with higher N in stover than their
respective non-Bt near-isolines…Our data suggest that within the same maturity group, it
was the superior hybrids (non-Bt trait) that led to the greatest N accumulation, and the highest
grain yield. Under the conditions tested, there was no yield advantage of Bt hybrids in
comparison with their conventional counterparts when stalk lodging and breakage of the
non-Bt counterpart by ECB [European corn borer] was low to moderate (Ma and Subedi,
2005, p. 199).
[Argentina and China/soybeans and cotton:] Roundup Ready (RR) soybeans did not increase
yields in Argentina, but did reduce pesticide costs, which increased farmers’ profits. Results
of Bt cotton studies were pretty consistent – Bt cotton leads to increases in yields, decreases
in pesticide use and increases in profits in all four countries. The only difference was that in
low pesticide-use countries – Argentina, Mexico and South Africa – use of Bt cotton led to
increases in total cost of production while in China it reduced the cost of production. (Pray
and Naseem, 2007, p. 201).
[Canada/oilseed rape:] Information comparing yields of HT with conventional oilseed rape
varieties are contradictory, indicating either yield increases, equivalence or decreases (Graef
et al., 2007, p. 115).
[Spain and South Africa/maize:] There are very few reports on the economic performance of
Bt corn in other parts of the world. For the United States, the largest grower of Bt corn, onfarm
evidence is limited to the early years of adoption (1997-1999) and points to very variable
economic effects resulting from large differences in geographical incidences of corn
borers. In South Africa, the Bt corn-yield advantage, together with reduced pesticide costs,
increased income from €19.2 per hectare to €119 per hectare, a range similar to our findings
in Spain (Gomez-Barbero et al., 2008, p. 386).
[Australia/oilseed rape:] The vegetative vigour, overwintering capacity, time to maturity, seed
production and yield of HT canola fall within the normal range for conventional canola
(Salisbury, 2002, p. 12).
Conclusions
There is no conclusive data from either developed- or developing-country
agroecosystems to support generic claims that GM crops increase yield or revenue. It is
undoubtedly true that any cultivar, transgenic or not, will produce more or less depending
on year, location and other variables. GM crops are not being asked to achieve a higher
standard than conventional crops on this point. However, any general claim that GM crops
will reliably produce more than conventional crops in the same environments is not scientifically
substantiated. Poor and subsistence farmers cannot gamble with their potential to
produce food for their families and communities. Coupled with higher upfront costs for
GM seeds, amongst other production and market risks (i.e., see liability topics in Chapters
Four and Eight), reliable returns from genetic engineering are not certain.