The National Agricultural Statistics Service (NASS) of the USDA will release the first yield and production forecasts for the 2012 U.S. corn and soybean crops on Aug.10. The first forecasts of the season are always highly anticipated, but none more than this year as widespread drought conditions have resulted in a wide range of yield and production expectations, according to University of Illinois Agricultural Economist Darrel Good.

“While the USDA’s August forecast will provide a benchmark for the size of the 2012 corn and soybean crops, the market will continue to form yield expectations beyond the release of the report,” Good says. “Analysts use a combination of techniques to judge yield potential, including crop condition ratings, crop weather models, satellite imagery and analogue years. In the case of analogue years, there were six previous years since 1960 when the U.S. average corn yield was more than 10% below the unconditional trend yield. The shortfall in those years ranged from 10.4% to 25.6% and averaged 17.5%. A U.S. average yield 17.5% below trend would result in a 2012 average yield of 131 bu., while a yield 25.6% below trend would result in an average yield of 118 bu.

“There were also six previous years since 1960 when the U.S. average soybean yield was more than 10% below the unconditional trend yield. The shortfall in those years ranged from 11.8% to 19.3% and averaged 14.9%. A U.S. average yield 14.9% below trend would result in a 2012 average yield of 36.7 bu. while a yield 19.3% below trend would result in an average yield of 34.8 bu.,” Good says.

Good reports that, in addition to yield, the size of the 2012 crops will be influenced by the magnitude of harvested acreage. “Harvested acreage, particularly for corn grain, may be unusually small in relation to planted acreage, further reducing production potential. The corn and soybean markets continue to trade smaller and smaller crops, but prices may not yet reflect the full extent of production shortfalls,” he says.

Good provides a review of the NASS methodology for making corn and soybean yield and production forecasts. Data for the forecasts are collected in two separate surveys conducted roughly in the last week of July and the first week of August for the August report.

The Agricultural Yield Survey (AYS) queries farm operators in 32 states for corn and 29 states for soybeans asking operators to identify the number of acres to be harvested and to forecast the final average yield. The sample of operators is based on a sophisticated sample design to achieve the desired sample size, and each state is expected to achieve a minimum response rate of 80%. In 2011, approximately 27,000 operators were surveyed for all crops for the August report. Each operator is surveyed in subsequent months to obtain new forecasts of acreage and yield. Historical relationships indicate that respondents tend to be conservative in early forecasts of final yields (to underestimate yield potential), particularly in drought years. This tendency is quantified and factored into official yield forecasts.