The major agricultural commodities produced in the U.S. have a relatively low per-acre value. In the past, crop prices often failed to keep pace with inflation. For example, the average price paid to farmers for soybeans in 2000 was $4.40 per bushel, the lowest average price since 1972, and a 40 percent decline since 1996. Over the past couple of years, this has been changing. For instance, in 2012 the cost of soybeans increased to $14.30 per bushel.
USDA tracks both prices received for farm products and prices paid for production inputs. Using the 1910-1914 period as a base, the prices received by today's farmer have increased by at least a factor of six. However, prices paid by farmers for production inputs have increased by at least a factor of sixteen! For statistics on crop totals (prices), visit USDA's National Agriculture Statistics Service here: http://www.nass.usda.gov/Statistics_by_Subject/index.php?sector=CROPS.
Thin profit margins have forced producers to seek efficiencies in all aspects of production. Efficiencies of scale favor large producers who can make the most effective use of large, expensive machines. For crops such as corn and soybeans, commercial viability is based on producing "in volume." These forces have dramatically changed the size and numbers of farms.
In addition to efficiencies in machinery and crop production volume, crop inflation costs and crop production expenses are linked to various other factors including gas prices, weather conditions, environmental events, and consumer demand related to crops.
U.S. USDA. Economic Research Service. Food Price Outlook: Summary Findings. N.p., n.d. Web. 09 Apr. 2013. <http://www.ers.usda.gov/data-products/food-price-outlook/summary-findings.aspx>.
"World Food Prices Rise to Near-Record High as Inflation Speeds Up, UN Says." Bloomberg. N.p., 5 May 2011. Web. 09 Apr. 2013. <http://www.bloomberg.com/news/2011-05-05/food-prices-approach-record-high-as-grain-prices-fuel-inflation-worldwide.html>.