For many no-tillers, it’s difficult enough to get crops planted and harvested on time each year. But after harvest, there’s often another battle — managing residue in such a way that it’s an asset to their rotation, rather than a liability.
Farmers raising Bt corn are especially concerned, with some comparing the stalks left in fields to pieces of rebar sticking out of the ground. Those who raise winter wheat may also deal with corn residue or wheat straw that sticks around too long.
But soil scientists and agronomists point to soil microbes — and the power of no-till and cover crops — as the primary answer for this problem.
There are three main components of plant residue that no-tillers need to worry about in the decomposition challenge, says Doug Miller, an agronomist and vice president of Midwest Bio-Tech in Erie, Ill.
The first is cellulose, which has relatively large but unbranched molecules. The second is hemicellulose, which has shorter molecules that are branched together. Hemicellulose provides a network that holds together cellulose and other components within the cell walls, Miller says.
But the third component, lignin, is the toughest customer, as it’s a very long, complicated and dense chain of atoms strung together, he says. Lignin provides a great deal of strength to the plant as it stands up during the season, especially after ears are set on corn, or heads develop in wheat.
Microbes in the soil turn the decomposition of residue into chemical…