Among the contradictions in corn culture is the need to have corn stalks maintaining upright plants through harvest but rapid deterioration in soil between seasons and /or efficient decomposition for fermentation to recover the carbon in ethanol or energy for cattle. Primary strength during the growing season is derived from a combination of the tight connection of the pith cells to the outer rind cells, fibers and near the outer rind and thick cell walls of the outer rind cells.
Stalk components after harvest range among hybrids. About 50% of the solid weight is composed of carbon but most of it is involved in complex molecules such as cellulose, hemicellulose and lignin. Although lignin composition is only about 7% of the stalk, it is the most difficult to digest and often is wrapped around the more easily decomposed cellulose molecules.
Multiple fungal species in the soil produce enzymes capable of breaking and modifying the lignin molecules. Tree wood, mostly composed of lignin, is slowly destroyed by fungi specializing in production of lignocellulolytic enzymes. These initial wood rotting species are succeeded by other fungal species that enzymatically degrade the cellulose into its components. Genetic variation among fungi and competitive pressure for obtaining the energy locked up in corn stalks provides multiple sources to break down the complex carbon compounds that provided strength for the corn stalk previous to harvest.
Among the challenges for all interested in corn is to identify hybrids that produce stalks that remain upright through harvest but can be efficiently digested by cows, fermentation and soil organisms.
Published in Corn Journal 11/1/2018
About Corn Journal
The purpose of this blog is to share perspectives of the biology of corn, its seed and diseases in a mix of technical and not so technical terms with all who are interested in this major crop. With more technical references to any of the topics easily available on the web with a search of key words, the blog will rarely cite references but will attempt to be accurate. Comments are welcome but will be screened before publishing. Comments and questions directed to the author by emails are encouraged.