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Corn Harvest Quality Report 2014/2015

Contents

  1. Harvest Quality Highlights
  2. Introduction
  3. Quality Test Results
  4. Moisture
  5. Chemical Composition
  6. Physical Factors
  7. Mycotoxins
  8. Crop and Weather Conditions
  9. Planting and Early Growth Conditions - Spring (March - May)
  10. Pollination and Grain Fill Conditions - Summer (June - August)
  11. Harvest Conditions (September - October +)
  12. Comparison of the 2015 Average to the 2014, 2013, and 4YA
  13. Corn Production, Usage, and Outlook
  14. U.S. Corn Use and Ending Stocks
  15. Outlook
  16. Survey and Statistical Analysis Methods
  17. Survey Design and Sampling
  18. Statistical Analysis
  19. Testing Analysis Methods
  20. Corn Grading Factors
  21. Moisture
  22. Chemical Composition
  23. Physical Factors
  24. Mycotoxin Testing
  25. U.S. Corn Grades and Conversions
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C. Statistical Analysis

The sample test results for the grade factors, moisture, chemical composition, and physical factors were summarized as the U.S. Aggregate and also by three composite groups that supply corn to each of three major export channels, labeled Export Catchment Areas (ECAs), as follows:

  • The Gulf ECA consists of areas that typically export corn through the U.S. Gulf ports;
  • The Pacific Northwest (PNW) ECA includes areas that export corn through Pacific Northwest and California ports; and
  • The Southern Rail ECA comprises areas generally exporting corn to Mexico.

In analyzing the sample test results, the Council followed the standard statistical techniques employed for proportionate stratified sampling, including weighted averages and standard deviations. In addition to the weighted averages and standard deviations for the U.S. Aggregate, weighted averages and standard deviations were estimated for the composite ECAs. The geographic areas from which exports flow to each of these ECAs overlap due to available transportation modes. Therefore, composite statistics for each ECA were calculated based on estimated proportions of grain flowing to each ECA. As a result, corn samples could be reported in more than one ECA. These estimations were based on industry input, export data, and evaluation of studies of grain flow in the United States.

New to this Harvest Report 2014/15 is a simple average of the quality factors’ averages and standard deviations of the previous three Harvest Reports (2011/12, 2012/13 and 2013/14). These simple averages are calculated for the U.S. Aggregate and each of the three ECAs and are referred to as “3YA” in the text and summary tables of the report.

The Relative ME was calculated for each of the quality factors for the U.S. Aggregate and each of the ECAs. The Relative ME was less than ±10% for all the quality attributes except for SCI for the U.S. Aggregate and the Gulf and Southern Rail ECAs, and total damage, stress cracks and SCI for the Pacific Northwest ECA. The Relative ME for total damage, stress cracks and SCI was as follows:

While the lower level of precision for these quality factors is less than desired, these levels of Relative ME do not invalidate the estimates. Footnotes in the summary tables for “Grade Factors and Moisture” and “Physical Factors” indicate the attributes for which the Relative ME exceeds ±10%.

References in the “Quality Test Results” section to statistical and/or significant differences between 2014 and 2013 and 2014 and 2012 test results were validated by two-tailed t-tests at the 95% confidence level. The t-tests were calculated between results in the Harvest Report 2012/13 and the Harvest Report 2014/15 and the Harvest Report 2013/14 and the Harvest Report 2014/15.