The Impact of Accurate Moisture Measurements in Grain


Whichever sector of the grain industry you work in – be it production, trade or processing – it probably won’t be news to you that the moisture content of grain demands constant attention. Being able to accurately assess the moisture content of grain has long been essential for important decision-making throughout the industry:

  • Is this a good time to be harvesting?
  • How long should I dry for?
  • Which batches should be blended together?

Accessing this information quickly has previously been challenging due to the technical limitations of instrumentation. However, in the last few decades there has been tremendous progress in terms of both speed and accuracy. In such a high-volume industry, where trucks, trains and ships full of grain change hands every day, it is important that the grain industry ensures that they are implementing the latest technology for measuring moisture content.

H2Oh No!

When trading grain, it is crucial that the moisture content is within an acceptable range in order to maximize profitability. This is because in all cases, grain is bought and sold on the basis of its weight, of which water content is a significant factor. The maximum moisture content of different grains is coded in the grain standards of individual countries, although most align with FAO guidelines.

For instance, in the US and many other countries, the standard moisture content of corn is set to 15.5%, although notably in the EU this threshold is 14%. Every drop of water above these thresholds represents a payment penalty, as the weight will be adjusted down with a ‘shrink factor’ to reflect the weight of the excess water. Every drop of water below the thresholds results in the grain being undersold as no compensation is provided for the lower water weight.

One of the roles of the Federal Grain Inspection Service (FGIS) in the US is to assign an official grade, including moisture content, to any grain exports leaving the country. If the moisture content of a grain shipment strays too far from standard values, it may not meet grade and it may not be accepted by the receiving elevator.

However, standard values for trade are not the only reason to be concerned with moisture. At all stages of the grain industry, grain that has a moisture content that is too high, or too low, can cause serious headaches for both producers and traders. The self-heating property of wet grain is a well-documented issue and without sufficient chilling or drying, it has been known to spontaneously combust.

More commonly, grain with a high moisture content spoils during transport and storage. On the other hand, if grain is handled when it’s too dry, it is much more susceptible to breaking and cracking. A high percentage of broken or cracked kernels in a batch of grain will lower its grade and corresponding value. These issues affect all grains, from Amaranthus to Zea and everything in between. Accurate and rapid moisture measurements can enable stakeholders in the grain industry to manage these problems more effectively by informing decisions that help to maintain optimum moisture content. In turn, this will also maximize a business’ profitability.

Getting it Right from Farm to Fork

The United States Department of Agriculture’s (USDA’s) reference method for determining moisture in grain relies on evaporation via an air oven. While this is highly accurate, it is generally a multi-hour process, which is not practical for an industry where trade transactions must be carried out in minutes or even seconds. For this reason, since the 1970’s, secondary methods have arisen to provide quicker results. These invariably measure physical characteristics of the grain such as electrical conductance, calibrated to provide an accurate prediction of the result from the air oven.

The different secondary methods on the market for measuring moisture content are standardized per grain trade regulations, and are often viewed as equivalent perceptually in the field. However, staying up to date with advancing technology has several key advantages that can increase a business’ efficiency and competitiveness.

The latest generation of dielectric moisture meters for use by producers and traders – those approved by the FGIS for official measurements – are calibrated out of the box to deliver results within ten seconds. These meters also offer a 50% reduction in measurement error relative to the previous generation of meters. This improvement in precision can have a large impact on a business’ profitability, as the ability to increase measurement confidence levels from one percentage point to one tenth of percentage point means that moisture content margins can be tightened significantly. These meters also offer increased reliability over older generations in the potentially unstable temperature and humidity conditions on farms and at grain elevators.

At processing facilities, the latest near infrared (NIR) instrumentation can provide continuous moisture measurements within the production line. The technology can provide accurate information on moisture content in a wide variety of grain-based products including everything from liquids and pastes to snack foods like potato chips.

In addition, NIR instruments can provide multi-parameter measurements, providing information on fat or protein content as well as moisture. This is particularly useful in processing facilities that handle commodities valued by these parameters.

The advantages of the latest moisture meters extend beyond enhanced accuracy and reliability. Increased automation and minimal sample handling facilitates simple integration into workflows throughout the grain industry. Automation also ensures that the results are completely operator-independent and objective.

This further increases the dependability of assigned moisture content and is vitally important when conducting high-value trade. In addition, digital storage of sample management history and improved connectivity means that information on moisture content can easily be shared between stakeholders in the industry.

Knowledge is Power

Knowing the moisture content of grain empowers those working in the industry to optimize their processes and rapidly take decisions that will positively affect their bottom line. For producers, being able to obtain accurate moisture measurements within ten seconds means decisions can be made quickly on whether conditions are suitable for harvesting. Avoiding harvesting crops when they are either too wet or too dry leads to great improvement in the storage and handling of grain.

For traders, when drying grain that has a high moisture content, quick and accurate moisture measurement can facilitate stopping the process before the grain becomes over-dried. Over-drying grain carries a costly twofold penalty for a business, as dropping below standard moisture content will reduce the grain’s value and the large amounts of energy required to dry grain is highly expensive.

Accurate moisture measurements also allow traders to understand which batches of grain they can blend together to arrive at optimum moisture content. For processors, in-line NIR moisture measurements enable the creation of a closed-loop optimization process, whereby moisture content of products is constantly monitored so that process parameters can be adjusted accordingly.

When selling an entire rail car full of wheat, even a sub-percentage point error in moisture content can result in vast amounts of lost revenue. Adopting rapid, accurate and operator-independent technology can allow businesses to ensure they get the most value out of every bushel of grain, down to the last kernel.


  1. FAO. Grain Standards. Publications Office of the European Union. Commission Regulation (EEC) No 689/92 of 19 March 1992 Fixing the Procedure and Conditions for the Taking-over of Cereals by Intervention Agencies,
  2. CELEX1.
  3. USDA. Reference Methods | Agricultural Marketing Service.
  4. USDA. Moisture Equipment | Agricultural Marketing Service.