Crop Yield: Definition, Formula, and Statistics

What Is Crop Yield?

Crop yield is a standard measurement of the amount of agricultural production harvested per unit of land area. It's the measure most often used for cereal, grain, or legumes and it's typically measured in bushels, tons, or pounds per acre in the United States.

Sample sizes of a harvested crop are generally measured to determine the estimated crop yield for a larger region.

How Crop Yield Works

Producers usually count the amount of a given crop harvested in a sample area to estimate crop yield. The harvested crop is then weighed and the crop yield of the entire field is extrapolated from the sample.

The crop yield estimate using the standard formula would be 30 x 24 x 35 x 0.04356 = 1,097 kg/acre if a wheat producer counted 30 heads per foot squared and each head contained 24 seeds, assuming a 1,000-kernel weight of 35 grams. The estimated yield would be 40 bu/acre (1097/27.215) or 40 bushels per acre because wheat is 27.215 kg/bu.

Crop yield can also refer to the actual seed generation from the plant. A grain of wheat yielding three new grains of wheat would have a crop yield of 1:3. Crop yield is sometimes referred to as "agricultural output."

Crop Yield Statistics

The U.S. Department of Agriculture (USDA) produces charts and maps that display crop yields, crop weather, and crop acreage animations. They help U.S. farmers maximize agricultural product output. ​The USDA provides many statistics about crop yields for various agricultural products. It publishes a monthly report of field crop yields for dozens of products including barley, rice, tobacco, and wheat.

Part of this information is the absolute high and low yield for the entire history of the data series, some of which extend back over 150 years. The absolute low crop yield for many products occurred in the 1930s during the Great Depression and the Dust Bowl years. High crop yield has regularly occurred in the years since 2000.

Crop yields, farm efficiency, and agricultural product output in the U.S. have increased dramatically as technology has advanced in farm automation, crop genetics, fertilizers, and pesticides.

Special Considerations​

Crop yield data is important not only in the U.S. but abroad as well. Declassified CIA documents show that the U.S. government has used satellite reconnaissance imagery to estimate the crop yields of foreign countries. This was particularly important in the 1960s during the height of the Cold War when the U.S. was using such methods to assess the agricultural health of China and the Soviet Union.

Foreign countries frequently publish crop yield statistics on their government websites, similar to what the USDA does in the U.S.

The Bottom Line

A crop yield is a measurement of the quantity of specific crops produced in a cited region. The yield varies by crop and the USDA monitors almost two dozen. Crop yield and farm efficiency in the U.S. plunged during the Great Depression but they've increased significantly in the 2000s thanks to technology. A nation’s food supply and energy sources depend on healthy crop yields and this can affect consumers by trickling down to pricing.