Corn, Beans, and Burgers: Field Crops in Sustainable Agriculture
Module II > Section A : Field Crops in the Food System

Section A: Field Crops in the Food System

Projected outcomes

  1. Students will know how the principal field crops from Iowa and Wisconsin contribute to their food system.
  2. Students will begin to understand how the field crops from Wisconsin and Iowa fit into the world food system.
  3. Students will begin to appreciate the complexity of the relationship between crop production and food distribution.

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Background / Lessons

We all know agriculture is about growing food, but sometimes the connections between crops and food are pretty indirect. This section uses two activities (Activities 1 and 3) to build student understanding of the relationship between field crop production and the food we actually eat. To prepare for the first activity, ask students to bring a week’s itemized grocery receipt or shopping list and a selection of ingredients labels to class.

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What are our principal field crops?

The principal field crops in Iowa and Wisconsin are:


Acres, IA

Acres, WI

Acres total

Corn (grain or seed)








Corn (silage)




Alfalfa, hay, etc.




Wheat for grain








*Small grains include oats, wheat, barley, and rye, harvested for grain. When harvested for green chop or hay these crops are counted as hay.

Data from tables 1, 37, and 38 in USDA, NASS, 2012 Census of Agriculture, State Level Data


More than half of the cropland in Iowa and Wisconsin is in field crop production. 70% of Wisconsin’s cropland and 90% of Iowa’s cropland is planted to just 3 crops: corn, alfalfa, and soybeans. How are these crops used? Where do they go?

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How Do We Use These Crops?

Activity 1: The Crops on Our Plates


All the silage corn is used to feed livestock, primarily dairy cows.

Most grain corn also goes to feed livestock. In 2009, American farmers harvested about 13 billion bushels of corn grain. Iowa produced about 19% of the U.S. corn crop - around 2.4 billion bushels. For many years corn use was quite stable, with about 75% going to feed livestock in the US and other countries, 8% going to fuel ethanol, and more than 6% going to sweeteners. Since 2004, however, the portion of the corn crop used for ethanol has more than tripled to 27 to 30 percent in 2009 and 2008 and the portion used directly for feed has dropped to about 40 to 45 percent. A substantial portion of the by-products of ethanol production (distillers’ grains) are fed to livestock, so the corn used for ethanol also contributes to animal feed.

2002 U.S. Corn Use by Segment
From Iowa Corn Growers Assoc. website.

2010-11 Corn Use by Segment

Based on data in USDA ERS Feed Grains Database: Yearbook Tables 4 and 31, accessed June 2012.

See also Iowa corn use

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Activity 2: How much corn is 2 billion bushels (Iowa’s corn harvest)?

About 15 to 20 percent of grain corn in the US is exported. Most corn exports are used to feed livestock. Japan is the leading importer of US corn, followed by Mexico. (Japan takes about 30% of our corn exports, and Mexico and South Korea combined imported another 30% in 2010-2011).

About 50 percent of grain corn is used for seed, industrial uses, and food in 2008. The major industrial use is for ethanol production (about 38% of the total 2010 grain crop). The main food use is for sweetener (for example in soft drinks, jams and jellies, and a wide range of processed foods). Corn Refiners Association Statistics Less than 5% of the US grain corn crop goes to human food other than sweetener.


A little over half of the US harvest is crushed for oil, and the residue, called soy meal, is fed to livestock. Oil goes primarily to edible uses (shortening in baked goods, frying oils, salad oils, margarine, coffee creamers, mayonnaise, etc.) and accounts for about 60% of the vegetable oil used in the US. The rest goes to industrial uses (diesel fuels, inks, pesticides, soaps, shampoos, and detergents, etc.) Use of soybean oil for biodiesel has increased from about 2 million gallons in 2000 to more than a billion gallons in 2012 and now accounts for between 20 and 24% of the total soybean crop. SoyStats 2013.

In 2013 about 45% of harvest was exported (some used for oil & livestock feed; some for human food, esp. in Asia)

About 3% of the soybean harvest used in US is not crushed for oil and goes to seed, feed, human food, and industrial uses. Human food examples include soymilk, tofu, roasted soy nuts, infant formula, soy sauce, edamame. Standard high yield soybean varieties are not suitable for many non-oil human food usues.


All of the alfalfa is used to feed livestock, primarily cows (both beef and dairy).

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How Do These Crops Get to Us?

Activity 3: A Look at Processing and Distribution

One of the main ingredients in carbonated soft drinks is high fructose corn syrup (HFCS). What are the steps between the corn growing in the field and the can of soda on the grocery store shelf?

Let’s trace back how the corn got into one example can of soda.

Flowchart for a Soft Drink (MS Word Document)

For generic flow charts for corn and soybeans visit the National Feed and Grain Association

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Field crops play a major role in our agricultural system. Just three species, corn, soybeans, and alfalfa, account for well over half the cropland in Wisconsin and Iowa.

The primary use of these crops is for livestock feed. Other uses include fuels and industrial ingredients, and oils, sweeteners, and stabilizers for processed foods.

The portion of the field crop harvest that goes to human food is mostly heavily processed. Most consumers know little about what activities and companies are involved in the production of the processed foods they buy, and that information is not easily accessible. Also, because grains are pooled and marketed globally it is not possible to track a particular farm’s grain to an end food product if it is marketed in the general commodity pool.

Because field crops are so dominant, the ways they are raised, handled, and marketed will have a major impact on the sustainability of our agricultural environment and economy as well as our food system. Section B of this module provides case studies of sustainable field crop production. Sections C and Section D cover the ecology and economics of field crop production. Section E addresses the controversy surrounding the use of transgenic field crops.

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Career Pathway content standards

Projected Outcome National Agricultural Education Standards
Performance Element or
Performance Indicators
Activity Number(s)
(in this section)
1. Define a field crop and identify different field crops grown in the region that contribute to their food system. ABS.05.01 Maintain and interpret financial information for businesses.
FPP.04.02 Evaluate, grade and classify processed food products.
2. Describe how field crops in the region fit into the world food system. FPP.04.02 Evaluate, grade and classify processed food products. A-1, A-2, A-3
3. Identify the complex relationships that exist between producing crops and food distribution. FPP.01 Examine components of the food industry and historical development of food products and processing. A-3
4. List examples of sustainable farms both in the region and around the country and world. --- A

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