Corn seed containing bacillus thuriengensis (Bt) and other genetically modified traits have played a big role in the continued increase in corn yields across the country. Like most things, the good comes with a little taste of bad medicine.

The slow decomposition of Bt-containing corn stalks after harvest has been heralded by some as another good thing, because it may slow feeding of insects and make laying eggs more difficult for other insect species and generally provide a less desirable environment for both insects and disease organisms.

However, research and plenty of farmer reports in recent years indicate these slow decaying corn stalks, which produce a high yield and high volume of residue, tie up a lot of nitrogen in the soil and in some fields has caused a nitrogen deficit.

The time required for conventional or Bt corn stalks to decay depends on the carbon-nitrogen ratio. This is simply the ratio of carbon to nitrogen in the corn stalk. Though the problems associated with poor nitrogen performance in corn is commonly attributed to thicker rind and slower degradation of the stalk, the problem existed long before Bt corn hit the market.

Whether or not Bt-corn stalks decay slower than non Bt-corn stalks is still open for debate. Early research indicated some differences, but recent USDA studies indicate no difference in rate of stalk decay in Bt-corn versus non Bt-corn.