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Monitoring grain for quality and pest control

Storage monitoring systems are ideal for very large silos, where the size and design make it difficult to check for storage pests and to monitor internal storage conditions.
Photo: Alistair Lawson

Regular monthly storage checks for pests using an insect sieve and probe traps are critical to ensure pest damage to grain quality is minimised and grain is ready for sale when needed.

Along with monitoring pests, grain temperature and humidity in storage are two of the most important factors for maintaining grain quality.

Many growers make strategic use of early harvesting at higher grain moisture content. This provides flexibility for harvest operations and helps manage the risk of grain quality losses from wet weather at harvest. With these advantages, however, also comes the requirement to safely manage higher grain moistures in storages.

Various companies, including silo suppliers, now offer a range of grain monitoring equipment. Metrics provide accurate information on storage conditions, include grain temperature and relative humidity, which indicate the equilibrium moisture content (EMC) of the grain.

When temporarily holding high-moisture grain, sensors provide hourly grain temperature information to help growers check for safe storage conditions. If aeration drying grain is used, progress can be monitored with sensors providing grain equilibrium moisture content data.

Assessing equipment performance

For standard aeration cooling operations, sensors provide regular assessment of the performance of aeration equipment by checking the grain temperatures achieved throughout summer and winter.

An additional reason to encourage increased use of storage monitoring systems is the widespread investment by growers in large capacity flat-bottom and cone-based silos. These large silos (300 to 2000 tonnes) provide cost-effective storage, but their size and design make it difficult to check for storage pests and to monitor internal storage conditions.

Storage monitoring in its simplest form is achieved by using a 1.2 to 1.5-metre-long grain temperature probe, either pushed in at the top of a silo or through small ports in the side of a silo. Valuable storage information can be gained by measuring grain temperature alone.

Additional benefits are gained through measuring both grain temperature and humidity in a storage. This provides a clearer picture of storage conditions and grain moisture profiles throughout the storage.

Some sensors can measure fumigation gas concentrations to ensure that concentrations critical for pest control have been reached.

However, there are risks with fumigation. Trials have shown that humidity sensors inside a silo can be permanently damaged by phosphine gas during a standard fumigation. Some companies have recently started research and development work to address this and, in 2021-22, GRDC’s grain storage extension project will assess the durability of commercial grain monitoring systems under fumigation.

Prior to purchase, growers should carefully review the monitoring system’s build quality, sensor accuracy and design suitability for their grain storage system.

What to look for in a monitoring system

  1. Grain temperature measurement alone is valuable; however, monitoring equipment that reads temperature and relative humidity provides information to determine grain moisture content.
  2. Assess durability: sensor build quality, life span and long-term accuracy for each measurement – grain temperature, humidity and, in some cases, fumigant concentrations.
  3. Robust design is important. Grain sensors and cables are in a hostile environment with dust, heat, moisture and physical stresses when the silo is filled, emptied and as grain settles.
  4. The location of sensors inside a silo is important. If sensors are too close to silo walls, readings may be influenced by excessive grain trash or external temperatures, which are influenced by sun or shade on walls.
  5. Some sensors may be difficult to install in silos and to access later if they require maintenance.
  6. Ensure reliable communication of data between the internal storage sensors and the external receiver.

More information: Philip Burrill, 1800 WEEVIL,

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