Test weight in small grains
Test weight in small grains including wheat, oats and barley is an important component of crop quality and value. The test weight of a representative sample of your crop will give an indication of how it compares to the industry standard. A lower test weight equals lower value. Standard or higher test weights generally bring the best price and provide the best quality when fed to livestock on-farm.
Below are standard bushel weights (test weights), standard grain moisture contents and pounds per cubic foot (at standard test weight) for selected small-grain crops in Michigan.
• Management decisions can influence small-grain’s test weight at harvest.
• A lower test weight for small grains equals a lower value.
• Knowing grain moisture can be helpful in avoiding storage problems.
Growers will be informed of the grain’s test weight at the elevator, but it doesn’t hurt to determine it for yourself. Knowing grain moisture can be helpful in avoiding storage problems. Many grain moisture meters are available. Be sure to follow instructions carefully and collect a good, representative sample for the most accurate results.
Several factors influence the test weight of small grains, including drought, nutrient deficiencies, temperature extremes, plant lodging, insect damage and adverse weather events like frost and hail. There are also genetic differences among varieties. These factors influence the plant during the period of grain fill, when stress is most likely to reduce test weight.
Maximizing test weights
In order to achieve the best test weights, follow these tips:
• Adequate fertility. When available nitrogen is deficient, test weight will be lower. However, once nitrogen requirements are met, extra nitrogen has the potential to result in reduced test weight. Managing nitrogen carefully to meet, but not exceed, yield goals maximizes the likelihood of a good test weight. Crop rotation and manure or other soil amendments, as well as commercial fertilizers, should be considered when estimating available N.
• Insect pest management. Insects can damage foliage and stem tissue. Keep an eye out for armyworm infestations, excessive numbers of grasshoppers and others. When foliage or stems are eaten or damaged during grain fill, test weight will be reduced. Consider buying an armyworm trap to monitor the adult moths. Reusable traps cost less than $10, and annual pheromone baits cost about $5.
• Variety selection. Varieties showing superior test weight results in trials may be a good choice. However, other factors including yield and disease resistance are equally important.
• Avoid plant lodging. Avoid development of an overly dense canopy caused by excessive nitrogen rates early in plant development. Split application of nitrogen can help. Other causes of lodging include poor standability varieties, uneven fertilizer spreading equipment, stem-based diseases and poor plant anchorage resulting from poor soil structure.
For more information on test weight, crop weights and measurements:
• “Tables for Weight and Measure-ments: Crops” by William J. Murphy, University of Missouri Extension
• “Equivalent Weights of Grain and Oilseeds” by H. Hirning, K. Hellevang, J. Helm, N. Dakota State University
• “Bushels, Test Weight, Shrink and Storage” by Mike Rankin, University of Wisconsin Extension
Isleib writes for Michigan State University Extension.
This article published in the September, 2012 edition of MICHIGAN FARMER.