Toughened corn stalks are the bane of raising high-yielding corn today.

Bt corn, stay-green traits, great plant health, super stalk strength, foliar fungicides and nutrition — these are all characteristics of today’s production system and have led to steady increases in yield.

But these characteristics have also led to complaints that corn stalks just don’t decay fast enough in the field and create headaches for farmers — especially for those wanting to plant continuous corn, or who are strict no-tillers.

The Bt Challenge

“People talk about how tough cornstalks are with the Bt trait slowing down decay, but there hasn’t been a lot of laboratory work on why these stalks decay so slowly,” says Jill Clapperton, a soil health consultant and co-founder of Rhizoterra International in Florence, Mont. “The Bt trait does reduce corn-borer feeding, which maintains the integrity of the corn stalks.”

The slow decomposition of Bt stalks can be seen as a good thing, because it slows feeding of insects and provides a less-desirable environment for disease organisms that weaken and compromise stalks.

But high grain yields with huge amounts of slow-to-decay biomass tie up nitrogen in the spring, particularly in no-till fields.

So farmers are resorting to processing stalks with choppers, rippers, disks and vertical-tillage tools and incorporating them into the soil, or buying corn heads that shred stalks at harvest.

Decay Process

During decay of crop residue, ‘soil animals’ such as bacteria and fungi feed on the residue, using carbon for energy and creating stable organic…