You really can hear the corn grow! Acoustic emissions in the growth and breakage of maize

Abstract

Corn (or maize) is the leading grain crop in the United States. More than 350 million metric tons are harvested annually, generating twice as much revenue as any other crop. But a lack of understanding of corn stalk mechanics now hinders further improvement of corn production. The most promising new varieties of corn produce high yields, but are often susceptible to wind-induced failure of the stalk. Failure of this kind is prevalent at two distinct periods: in mid-summer during rapid growth, and after physical maturity, but before harvest. This study utilized acoustic measurements to collect new information about corn growth and failure. Measurements during the growth period were conducted in July 2016 at fields in Nebraska. Late-season stalk experiments involved stalks harvested from South Africa. Flexible, shielded piezo film sensors were used in all measurements (SDT1-028K, Measurement Specialties, Hampton, VA). Acoustic emissions were found to occur continuously during corn stalk growth, though typically at levels far below those audible to the human ear. The authors hypothesize that special conditions would be required to render these emissions audible to humans. Acoustic emissions provided valuable information which used to determine modes of stalk failure in late season lodging.