What is Crop Yield
Crop yield is a measurement of the amount of agricultural production harvested per unit of land area. Crop yield is the measure most often used for cereal, grain or legumes and is normally measured in bushels or pounds per acre in the U.S. (metric ton or kilogram per hectare outside the U.S.). The United States Department of Agriculture (USDA) produces charts and maps displaying crop yields, crop weather and crop acreage animations to help U.S. farmers maximize agricultural product output.
Crop yield can also refer to the actual seed generation from the plant. For example, 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."
BREAKING DOWN Crop Yield
To estimate crop yield, producers usually count the amount of a given crop harvested in a sample area. The harvested crop is then weighed, and the crop yield of the entire field is extrapolated from the sample.
For example, if a wheat producer counted 30 heads per foot squared, and each head contained 24 seeds, and assuming a 1,000-kernel weight of 35 grams, the crop yield estimate using the standard formula would be: 30 x 24 x 35 x 0.04356 = 1097 kg/acre. And since wheat is 27.215 kg/bu, the yield we estimated would be 40 bu/acre (1097/27.215) or 40 bushels per acre.
USDA Crop Yield Statistical Service
The USDA supplies many different statistics about crop yields for various agricultural products. For example, they publish a monthly report of field crop yields for 23 different products ranging from barley to rice to 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 extends back over 150 years. What is interesting to note is that, for many products, the absolute low crop yield occurred in the 1930s during the time of the great depression and dust bowl years, while the absolute high crop yield has occurred in the last year or two (2016/2017) as fertilizers, farming techniques and a robust economy have all contributed to record levels of agricultural product output in the United States.
Crop yield data is important not only in the United States 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. Today, foreign countries frequently publish similar crop yield statistics on their government websites, similar to what the USDA does in the United States.