The 2008 average corn and soybean yields for counties and districts in Iowa were released in early March 2009. Information was collected by the USDA National Ag Statistics Service Iowa Field Office each year through a County Agricultural Production Survey. The office has released official county estimates for corn and soybean acreage planted, harvested, yield and production for 2008.
Cherokee County was at nearly 55 bushels per acre and had the hisest average 2008 county soybean yield. The next highest county yield wa in Sioux at 54 bushels per acre. Cherokee and Ida Counties tied for the highest average 2008 county corn yield at 196 bushels per acre. The next highest county yields were in O'Brien and Sioux with both coming in at 195 bushels per acre. Kossuth County contined to maintain its position as the leading corn and soybean producing county in the state with 10.6 million bushels of soybeans and 53.9 millinon bushels of corn in 2008
Each year, approximately 20,000 randomly selected operators in Iowa are interviewed using an eight page questionnaire. The operator reports the whole farm's acres, planted, harvested, yield and production for corn, soybeans, oat, wheat, and hay, storage capacity, cattle inventory, hog inventory, goat inventory, sheep inventory, and any other livestock. They also are asked to report acres rented from someone else and cash rent paid for those acres.
The data for the sample of 20,000 are collected using several methods; mail, telephone interview, personal interview, or the operator can even report electronically. Data collection begins when corn and soybeans have reached 90 percent harvested in Iowa, typically around mid-November. Trained enumerators or census takers collect the data. The same enumerators are used to collect data for NASS year-round. Strict guidelines are followed by the Iowa office that match steps taken by other state Ag Statistics offices. This ensures comparable results on a national level.
Several steps are taken to check the reliability of the reports. The first step is a check for reasonableness, and any questionable results are double-checked with the operator. The results are then entered into a secure computer system checked again for extreme yields andoutliers in the data. At this point, the data are ready to be analyzed. NASS uses a system called Interactive Data Analysis System or IDAS. With this program, they can graphically look at all data that has been reported. It can be broken down by district and county at this point as well. During this phase, outliers are once again identified but by district and county. These are checked once more with the operator for reliability.
The data are then summarized by district and county indications (or point estimates) for acreage planted, harvested, yield, and livestock inventory. The summary indications are compared against "check data" from Farm Service Agency (FSA) and Risk Management Agency (RMA) at the county level. These finished estimates are reviewed by the NASS Ag Statistics Board in Washington, DC. This board reviews Iowa estimates as well as other states to check for consistency and once again for accuracy. After this final review, the yield reports are published and made available online.
Summary information is available on the Ag Decision Maker website. For other county estimates, including average livestock prices, crop reports, and farm numbers, visit the NASS website for Iowa at: www.nass.usda.gov/Statistics_by_State/Io....