How Much Land Does It Take To Produce Your Food



How Much Land Does It Take To Produce Your Food?

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Background:

Humans require energy and their energy is obtained from food. Energy moves from its source in the sun through the photosynthetic organisms that make that energy available to living things (producers) and then through organisms that eat other organisms (consumers). Land therefore yields fewer kilocalories per square meter per year in animal products than in plant products. Energy is lost in the transition from producers to consumers (respiration, heat loss, animal waste). Plants can be divided into two groups, C-3 and C-4, based on the photosynthetic and respiratory pathways they utilize. Under the right conditions C-4 plants such as sugarcane and corn photosynthesize two to three times as fast as C-3 plants. C-4 plants are also more efficient because they don't lose energy due to photorespiration which frequently occurs in C-3 plants. C-3 and C-4 plants are separated on the Analysis Sheet because the C-3 plants are less energy efficient. A final point to remember in dealing with food energy, a food Calorie used by nutritionists is equivalent to a kilocalorie (kcal) used by chemists and physicists.

Procedure:

1. Record the types and amount of food you have eaten during the past 24-hour period. Be sure to count everything, not just what is eaten at meals – include snacks, candy, etc. too.

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2. Using , determine the total number of calories taken in from your food during those 24 hours. Record this on the Analysis Sheet for Trophic Ecology of Humans.

3. Multiply this amount by 365 to determine the total number of calories you consume during a typical year.

4. Determine the square meters of land required to grow the food that you eat. Do this by determining the number of calories that fall into each food category and divide “annual consumption” by the "yield".

5. Add the values in the "square meters of land" for all C-3 plants, C-4 plants, and animal products to arrive at the TOTAL land required to support you for a year.

6. Determine the class average for the square meters of land required to support an individual.

Analysis Sheet for Trophic Ecology of Humans

|Food Category |Your Daily Consumption|Your Annual Consumption |Yield |Square Meters of Land Needed to |

| |(kcal / day) |(kcal / year) |(kcal / sq. m / year) |Support You |

| | | | |(Consumption ÷ Yield) |

|C-3 Plants |

|Bread | | |650 | |

|Wheat, cereal | | |810 | |

|Oranges, grapefruit | | |1000 | |

|Frozen orange juice | | |410 | |

|Peanut butter | | |920 | |

|Rice, rice cereal | | |1250 | |

|Potatoes | | |1600 | |

|Carrots | | |810 | |

|Other vegetables | | |200 | |

|Apples | | |1500 | |

|Pears, peaches | | |900 | |

|Vegetable oil | | |300 | |

|Margarine | | |300 | |

|C-4 Plants |

|Cane sugar | | |3500 | |

|Soft drinks | | |3500 | |

|Corn cereal | | |1600 | |

|Corn | | |250 | |

|Animal Products |

|Milk | | |420 | |

|Cheeses | | |40 | |

|Eggs | | |200 | |

|Chicken | | |190 | |

|Pork | | |190 | |

|Beef | | |130 | |

|Fish | | |2 | |

| |

|TOTAL = | |

|Class average = | |

Analysis:

Use the class average for the following calculations.

1. Assuming a football field/soccer field is 5000 square meters, how many fields does the average person need to support him/herself for one year? Show your work.

2. Calculate the amount of land needed to provide food for the following populations:

| |Sq. Meters |Sq. Kilometers |Acres |

|Kennedy High (pop. 2,000) = | | | |

|Cedar Rapids (pop. 126,326) = | | | |

|Iowa (pop. 3,046,355) = | | | |

|United States (pop. 308,745,538) = | | | |

Convert the square METERS to square KILOMETERS by dividing by 1 million.

An acre is 4047 sq meters. (slightly smaller than a football field)

3. On the Iowa map below, shade the area of land needed to support the populations of Kennedy High School, Cedar Rapids, and the State of Iowa. Use different colors to represent the needs of each of the population groups. Include a key.

4. Why can’t we use our calculations in this activity to determine the amount of land required to grow food for the entire world population? What other things must we consider?

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