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Corn Export Cargo Quality Report 2018/2019

Contents

  1. Export Cargo Quality Highlights
  2. Introduction
  3. Grade Factors
  4. Quality Test Results
  5. Moisture
  6. Chemical Composition
  7. Physical Factors
  8. Stress Cracks
  9. 100- Kernel Weight
  10. Kernel Volume
  11. Kernel True Density
  12. Whole Kernels
  13. Horneous (Hard) Endosperm
  14. Mycotoxins
  15. Assessing the Presence of Aflatoxins and Deoxynivalenol (DON)
  16. Background: Mycotoxins General
  17. Background: Aflatoxins
  18. Background: Deoxynivalenol (DON) or Vomitoxin
  19. U.S. Corn Export System
  20. U.S. Corn Export Flow
  21. Impact of The Corn Market Channel on Quality
  22. U.S. Government Inspection and Grading
  23. Survey & Statistical Analysis Methods
  24. Survey Design & Sampling
  25. Statistical Analysis
  26. Testing Analysis Methods
  27. Grade Factors
  28. Moisture
  29. Chemical Composition
  30. Physical Factors
  31. Mycotoxins
  32. U.S. Corn Grades & Conversions

Test Weight

Test weight (weight per volume) is a measure of bulk density and is often used as a general indicator of overall quality and as a gauge of endosperm hardness for alkaline cookers and dry millers. High test weight corn takes up less storage space than the same weight of corn with lower test weight. Test weight is initially impacted by genetic differences in the structure of the kernel. However, it is also affected by moisture content, the method of drying, physical damage to the kernel (broken kernels and scuffed surfaces), foreign material in the sample, kernel size, stress during the growing season, kernel maturity, kernel hardness and microbiological damage. When sampled and measured at the point of delivery from the farm at a given moisture content, high test weight generally indicates high quality, a high percent of horneous (or hard) endosperm and sound, clean corn. Test weight is positively correlated with true density and reflects kernel hardness and good maturation conditions.

Results

  • Average U.S. Aggregate test weight (57.4 lb/ bu or 73.9 kg/hl), well above the limit for U.S. No. 1 grade (56.0 lb/bu), was the same as 2017/2018, 2016/2017 and the 5YA. The 2018/2019 export samples had a standard deviation (0.82 lb/bu), below 2017/2018 (0.85 lb/bu), above 2016/2017 (0.61 lb/bu) and similar to the 5YA (0.80 lb/bu). The range in values in 2018/2019 was 7.6 lb/bu, similar to 2017/2018 (6.9 lb/bu) and wider than 2016/2017 (4.5 lb/bu).
  • Average U.S. Aggregate test weight for 84.4% of the 2018/2019 samples was at or above the minimum for U.S. No. 1 grade (56.0 lb/bu), and 97.7% of the samples were at or above the limit for U.S. No. 2 grade (54.0 lb/bu).
  • Average U.S. Aggregate test weight at export (57.4 lb/bu or 73.9 kg/hl) was lower than at 2017 harvest (58.4 lb/bu or 75.1 kg/hl). Average test weight at export has been consis- tently lower than at harvest, as indicated by the export 5YA (57.4 lb/bu or 73.9 kg/hl) and the harvest 5YA (58.1 lb/bu or 74.8 kg/hl).

  • The variability of the 2018/2019 export samples as measured by the standard deviation (0.82 lb/bu) was less than the 2018 harvest samples with a standard deviation of 1.20 lb/bu. As corn is commingled moving through the marketing channel, test weight becomes more uniform, with a lower standard deviation and a narrower range between maximum and minimum values than at harvest. The 5YA standard deviation at export was 0.80 lb/bu, compared with the har- vest 5YA standard deviation of 1.27 lb/bu.
  • Average test weight was lower for the Pacific Northwest (55.5 lb/bu) than for the Southern Rail (57.5 lb/bu) and the Gulf (58.0 lb/bu) ECAs.
  • Average test weight of corn for contracts loaded as U.S. No. 2 or better (57.5 lb/bu) was higher than for contracts loaded as U.S. No. 3 or better (57.4 lb/bu). Averages for both contracts were above the limit for U.S. No. 1 grade.

Broken Corn and Foreign Material (BCFM)

BCFM is an indicator of the amount of clean, sound corn available for feeding and processing. The lower the percentage of BCFM, the less foreign material and/or fewer broken kernels are in the sample. As corn moves from farm deliveries through the marketing channel, each impact on the grain during handling and transporting increases the amount of broken corn. As a result, the average BCFM in most shipments of corn will be higher at the export point than in deliveries from the farm to the local elevator.

Broken corn (BC) is defined as corn and any other material (such as weed seeds) small enough to pass through a 12/64th-inch round-hole sieve, but too large to pass through a 6/64th-inch round-hole sieve. Foreign material (FM) is defined as any non-corn material too large to pass through a 12/64th-inch round-hole sieve, as well as all fine material small enough to pass through a 6/64th-inch round-hole sieve. The diagram below illustrates the measurement of broken corn and foreign material for the U.S. corn grades.

Results

  • Average U.S. Aggregate BCFM in export samples but slightly lower than the 5YA and the U.S. No. 2 grade limit (3.0%). Average BCFM at export between years has been within ±0.1 percentage point for the past three years and the 5YA, indicating the ability of exporters to consistently manage cargo to meet importers’ specifications.
  • The variability of the 2018/2019 export samples (with a standard deviation of 0.67%) was similar to 2017/2018 (0.59%), 2016/2017 (0.68%) and the 5YA (0.66%). The range in values (8.4%) was wider than the 2017/2018 (4.9%) and 2016/2017 (6.0%)
  • BCFM in the 2018/2019 export samples was distributed with a 64.0% of the samples at or below the limit for U.S. No. 2 grade (3.0%), and 94.0% at or below the limit for U.S. No. 3 grade (4.0%).
  • Average U.S. Aggregate BCFM at export (2.9%) was 2.2 percentage points higher than at harvest (0.7%). This increase is the same as the 5YA. The harvest 5YA was 0.8% compared to the export 5YA of 3.0%. This increase is likely a result of artificial drying and increased breakage that occurs with additional impacts caused by conveying, dropping and handling as the corn moves through the marketing channel.
  • Average BCFM in the Southern Rail ECA (1.9%) was lower than either the Gulf (2.9%) or Pacific Northwest (3.5%) ECAs. Average BCFM for the Southern Rail ECA has also been lowest among the ECAs for the previous three years and the 5YA.
  • Average BCFM was 2.7% for contracts loaded as U.S. No. 2 or better compared to the average BCFM of 3.0% for contracts loaded as U.S. No. 3 or better. Corn arriving at the export point is normally commingled from many origins and may be cleaned to meet the limits for the contracted grade.

Total Damage

Total damage is the percent of kernels and pieces of kernels that are visually damaged in some way, including damage from heat, frost, insects, sprouting, disease, weather, ground, germ and mold. Most of these types of damage result in some sort of discoloration or change in kernel texture. Damage does not include broken pieces of grain that are otherwise normal in appearance. Mold damage and the associated potential for mycotoxins is the damage factor of greatest concern.

Mold damage is usually associated with high moisture content and warm temperatures during the growing season and/or during storage. There are several field molds, such as Diplodia, Aspergillus, Fusarium and Gibberella, that can lead to mold- damaged kernels during the growing season if the weather conditions are conducive to their development. While some fungi that produce mold damage can also produce mycotoxins, not all fungi produce mycotoxins. Chances of mold decrease as corn is dried and cooled to lower temperatures.

Results

  • Average U.S. Aggregate total damage (2.6%) was higher than the 2017/2018 (1.9%) and the 5YA (2.1%) but was similar to the 2016/2017 (2.7%); it was well below the limit for the U.S. No. 1 grade (3.0%).
  • Variability in the 2018/2019 samples, as indicated by the standard deviation (1.10%), was similar to 2017/2018 (1.02%), 2016/2017 (1.09%) and the 5YA (1.00%). The 2018/2019 sample range (0.0 to 10.5%) was similar to the 2017/2018 range (0.0 to 10.4%) but wider than the 2016/2017 range (0.1 to 6.8%).
  • Of the export samples, 64.9% had 3.0% or less damaged kernels, meeting the requirement for U.S. No. 1 grade. In addition, 94.7% were at or below the limit for U.S. No. 2 grade (5.0%).
  • The average level of total damage in the marketing channel at export (2.6%) was higher than at harvest (1.5%). The increase in total damage from the 2018 harvest to the 2018/2019 exports is higher than the changes seen in previous years. The export 5YA (2.1%) was 0.5 percentage points higher than the harvest 5YA (1.6%). Total damage can increase during storage, especially if there are spout lines and pockets of high moisture in the storage bins or transport containers.
  • The Pacific Northwest ECA had lower average total damage (0.7%) than the Gulf (3.3%) and the Southern Rail (2.4%) ECAs. The Pacific Northwest ECA also had the lowest average total damage among the ECAs for each of the last three years and the 5YA.
  • Average total damage for contracts being loaded as U.S. No. 2 or better (2.5%) and as U.S. No. 3 or better (2.8%) were below the limit for U.S. No. 1 grade (3.0%).

 

Heat Damage

Heat damage is a subset of total damage in corn grades and has separate allowances in the U.S. grade standards. Heat damage can be caused by microbiological activity in warm, moist grain or by high heat applied during drying. Low levels of heat damage may indicate the corn has been dried and stored at moisture contents and temperatures that prevent damage in the marketing channel.

Results

  • Average U.S. Aggregate heat damage was 0.0%, the same as 2017/2018, 2016/2017 and the 5YA. These averages have been below the limit for U.S. No. 1 grade (0.1%), indicating good management of drying and storage of the corn throughout the marketing channel.
  • Only eight samples in the entire 2018/2019 export cargo sample set (total of 436 samples) showed any heat damage (each was 0.1%).