Background

A Brief Overview of the Agriculture Industry and the Biology of Corn

Corn Biology 101

Corn, one of the United States' most valuable crops, was originally cultivated in Mexico in between 6,600 and 9,000 years ago.  Corn is unique in that it possesses both male and female reproductive organs and self-fertilizes.  Double-fertilization takes place within the corn plant, making the growing period very fast.  This allows for production of corn to be fast and efficient.

 Corn reproduction (1)

Corn is also a C4 plant, meaning that it engages in C4 photosynthesis to fix atmospheric carbon into energy.  This means that corn uses a four-carbon compound known as oxaloacetate to convert carbon dioxide and energy from the sun into energy, giving off oxygen as a byproduct (1).  

It is best to plant corn when soil temperatures are optimal for growth, usually around 10 degrees Celsius.  Different hybrid variations of maize grow within certain "heat units" required for maturity, so temperatures that exceed or fall below the necessary "heat units" will cause a the corn to not mature (2).  

The Corn Industry

Over 24 million ha of corn were planted in North America in 1993.  Corn is primarily produced for (2):

• domestic animal feed
• high fructose corn syrup
• starch or oil
• grits
• flour

Corn is also used to make plastics, compostable silverware, bakery products, alcohol, adhesives, and antibiotics (10).  Because corn grows quickly and it is relatively cheap to produce, it has become one of the largest exports for the United States.  

Ethanol

Ethanol is a biofuel made from corn, thought to be more energy-efficient than using fossil fuels.  Today, most fuel ethanol is produced by either the dry grind or the wet mill process, allowing for 2.5 gallons (wet mill process) to 2.8 gallons (dry grind process) of ethanol per bushel of corn (24).  The Renewable Fuel Standard, passed in 2005 and expanded in 2007, requires that 13.2 billion gallons of corn-based biofuel be produced in 2012. The goal of the standard is to reduce greenhouse gas emissions and the nation’s dependence on foreign oil.  About 40 percent of the nation’s corn crop is allocated to ethanol producers, and the remaining 60% goes to livestock feed, food, and exports (17).  

Ethanol production processes (24)