Simplifying the storage of grain, increasing its commercial value and avoiding the development of mould: this is why it is important to know as precisely as possible the moisture level of the grain before selling it. This is how to prevent fermentation processes from taking place and deteriorating the quality of the harvest.
We would therefore like to emphasize the importance of knowing the exact moisture content of cereals. In fact, knowing precisely the amount of water present in a cereal allows us to calculate the weight of the seed lot when dry and, consequently, its commercial value.
The moisture content of the grain therefore plays a crucial role in defining the relative market value of the finished product. Given that it is on the basis of these factors that the overall profit of a cereal-producing farm is actually determined, Mecmar offers three different ways of measuring the moisture content of the grain, viz:
- by measuring the temperature of the grain;
- by using a portable moisture meter;
- by installing a sensor in contact with the grain and connected to a panel display.
Curious to find out which of the three is the most suitable alternative for you? Read on to find out.
What is grain moisture content?
Grain moisture content is the quantity of water contained within a grain’s cellular structure, expressed as a percentage of its total weight. It is not merely surface wetness, but rather the internal water bound within the biological matrix of the kernel.
In agriculture and the global food supply chain, moisture content is widely considered the most critical factor for post-harvest management, influencing everything from the field to the final consumer product.
Safe moisture limits for storage
To prevent biological degradation, harvested crops must be dried down to what the industry calls “straight grade” or safe market standards. These thresholds represent the maximum allowable internal water content at which a grain can remain biologically dormant, suppressing the growth of molds, bacteria, and insects.
While the general rule of thumb for safe storage hover around $13\% – 14\%$, acceptable moisture percentages vary significantly by crop type and the intended duration of storage.
Why moisture content matters?
Managing moisture is a critical operational safeguard that directly impacts crop safety, processing efficiency, and market valuation.
Failing to hit the precise moisture target triggers a chain reaction across three main areas:
1. Spoilage, mold and biosecurity
Grains stored with excessive moisture cease to be dormant, turning the storage facility into an active biological ecosystem.
- The risk: high water activity creates an ideal breeding ground for storage fungi (such as Aspergillus), bacteria, and insect infestations.
- The consequence: beyond localized heating and physical rotting, mold growth can lead to the production of dangerous mycotoxins (e.g., aflatoxins). This can contaminate entire silos, rendering the crop toxic, illegal to sell, and a total financial loss.
2. Quality, milling and processing yields
Every grain variety has an optimal moisture “sweet spot” for mechanical processing. Operating outside of this window severely degrades the quality of the final product.
- Too wet: grains become soft and malleable. During milling, they flatten or clog machinery instead of fracturing cleanly, drastically reducing flour yield or oil extraction efficiency.
- Too dry: grains become brittle and glassy. Mechanical handling and milling (such as the hulling and polishing of rice) cause the kernels to shatter. This results in a high percentage of broken grains (e.g., broken rice), which immediately declasses the product to a lower-value market grade.
3. Weight vs. profit: the economic paradox
Because grain is traded commodities sold by weight, water content introduces a delicate financial balancing act for farmers and traders.
- The peril of excess moisture: selling grain with high moisture artificially inflates the total weight, which might seem profitable in the ultra-short term. However, this is heavily penalized by commercial buyers through steep price deductions (shrinkage factors) to cover drying costs, and it poses a catastrophic risk of the cargo spoiling mid-transit during shipping.
- The penalty of over-crying: conversely, drying grain below the market standard is a double financial loss. The farmer pays unnecessary energy and fuel costs for prolonged artificial drying, while simultaneously losing sellable weight. Essentially, they are evaporating their own profit margin.
Mecmar solutions for measuring the moisture content of grain
The first way of measuring the moisture content of the grain is to measure the temperature of the grain inside the mobile or tower dryer. In this way, by measuring the temperature of the grain, it is possible to determine the moisture level, following predetermined equilibrium curves.
Let’s take maize as an example. Once it is loaded into the agricultural dryer, the corn receives hot air evenly and uniformly, which raises the temperature of the grain to the desired level. The hot air circulating in the system heats the grain, which contains a progressively decreasing % of water, until an equilibrium point is reached where the grain is considered safe and ready to be stored. If the outside temperature is 20°C and the maize inside the drying plant reaches 55 – 58°C, then it is possible to proceed with the unloading phase as this means that the moisture content has dropped to 13 – 14%. This value also varies depending on the type of grain and the environment.
But indirect measurement of the percentage of water contained in the grain is not the only way to measure moisture content. If you are looking for a cheaper, more practical and faster method, we recommend that you choose a portable moisture meter.
Although not as accurate as much more expensive laboratory meters, this portable meter can be a good ally when recording the indicative progress of the drying process while using the dryer.
The portable moisture meter measures the moisture content of whole grains and seeds in the range of 8 – 35%, and for oil seeds 5 – 25%. The moisture meter quickly and easily determines the water content of 16 different grains, covering all popular cereal types.
Equipped with a large numerical display, a temperature compensation system and a robust aluminium frame, the Mecmar portable moisture meter is delivered to customers protected by a case that serves as a stand, a carrying strap and its battery. Its operation is simple and intuitive: a sample of cereal is inserted into the cylinder and within minutes the display shows the amount of moisture it contains.
Would you like to have an even more advanced and real-time grain moisture reading for your farm? Mecmar has the solution for you: a grain moisture meter with a digital display integrated into the control panel and a grain contact sensor. In this case, the control panel of your Mecmar dryer will be equipped with a moisture meter providing a real-time reading of the moisture content of the grain.
Once the grain reaches the moisture level (e.g. 14%) and/or temperature set at the end of drying, the burner switches off automatically. The cooling phase then begins.
Would you like to learn more about this topic? We also talk about it in these articles:
- Cereal grain drying and storage: how minimize losses
- Drying grain with aeration and heat: discover how it works
- How does a grain dryer work? Discover all you need to know
The most effective and reliable solutions for drying your cereals? Choose Mecmar quality
In order for the drying process to be carried out in the best possible way, it is essential to measure the moisture content of the grain. This is how we ensure that the quality of the grain remains unaltered over time.
Depending on the requirements to be met and the degree of accuracy desired, every farmer has the option of measuring the water content of the grain in three different ways. We summarise them briefly below:
- Indirect moisture measurement by measuring the temperature of the grain. The ideal solution for those who prefer to find out the amount of water in the grain without using optional instruments, but instead rely on the temperature the grain reaches during the drying process.
- Measuring the moisture content of the grain using a transportable cylinder apparatus into which a sample of already dried grain is inserted. With this method, moisture is measured easily and accurately, protecting the grain from deterioration. You can decide to use it anywhere, anytime.
- Measurement of the percentage of water in the grain by means of an RDS meter connected to the control panel using specific sensors and displays. Perfect if you want to know the moisture level of your crop in real time, this measurement mode provides an optimal indication of the development of the drying cycle.
Would you like to receive more information on the functionality of our dryers? Contact the Mecmar team: we will be happy to answer all your questions and curiosities.
