The later and more challenging harvest combined with movement issues has seen more grain lying on farm this autumn awaiting collection.  With grain being harvested at higher moistures than normal and having to be stored on farm for a longer period, this creates challenges for malting barley growers, particularly where there is little or no drying capacity on farm. Keeping the grain pile cool is vital, and this article will give you an overview of what can be done to ensure the safe storage of your malting barley.

Why safe grain storage is important

Safe grain storage not only preserves germination, but also the valuable premium and optimises value whereas poor management when stored even on a short-term basis can quickly see barley drop to feed value with extra costs incurred through drying and haulage.

The key factors that determine how long malting barley can be stored without a deterioration in germination are:

  • grain temperature
  • moisture content of the grain.

Bringing these down to safe levels as quickly as possible is key to managing wet grain successfully.

Top tips for managing wet grain

Preserving grain quality is key in years when grain is being harvested wetter than normal and there is more pressure on farm storage.

  • Measure grain moistures and temperatures immediately when harvesting.
  • Prioritise grain testing 18% m.c. or above for drying down to below 18%
  • Continually monitor grain piles for temperature and moisture, looking for changes. Hot spots can occur unexpectedly and need aerated immediately.

The science behind safe grain storage

Grain, just like most living organisms, produces carbon dioxide, heat and water as part of its respiration process. When grain is dry or below 14.5% - 15% moisture content (m.c.), respiration rates are low, and when combined with a lower grain temperature (10°C), grain can be stored safely for much longer periods. Where moisture content or grain temperatures are higher than this, storage periods are much shorter. In addition, higher moisture contents or grain temperatures provides a more favourable environment for the respiration process to take place, resulting in the grain generating even more heat.

When grain temperature in a bulk is left unchecked, this heating process accelerates, further reducing the safe storage period until the grain begins to deteriorate. As the heap heats up, not only does this compromise barley germination but can also lead to the formation of moulds and mycotoxins as well as providing the perfect environment for insect infestations to develop. Table 1 provides a guide as to how long barley can be safely stored in terms of germination demonstrates how storage period reduces rapidly as temperature and moisture increases.

Table 1. Estimated maximum storage life of barley with respect to germination

How to handle wet grain:

  • Test all grain immediately after harvest with an accurate moisture meter and grain thermometer.
  • All grain testing 18% m.c. or above should be stored separately and prioritised for drying. Drying should occur as soon as possible to take moisture content down below 18%.
  • Grain testing below 18% m.c. should be cooled down below 15°C to extend the safe storage period as long as possible.
  • Continue to monitor grain piles for temperature and moisture content. Hot spots can quickly and unexpectedly occur, reducing the safe storage period and therefore need cooling immediately to prevent a reduction in quality.
  • Plan tipping areas so that wetter grain that needs drying immediately doesn’t get blocked in by loads being tipped in front of it.
  • While a difficult harvest can see priorities lie in securing the crop, it is also important to ensure that storage facilities comply with end user’s terms and farm assurance standards.

Tips on Aeration

There are several different methods for aerating grain:

  • For stores with ventilation ducts, the grain surface should be kept as level as possible to ensure effective ventilation. To reduce any slopes at the front of the heap, where air will escape from more easily resulting in poorer airflow, placing a barrier to act as a wall is recommended.
  • Where pedestal fans are being used, deeper beds of grain can be ventilated without the same necessity for a level surface. As the air is sucked up through the grain however, if the grain is too shallow in places, this can lead to ineffective ventilation. Spacings between pedestals depend on the depth and moisture content of the grain and it is important that ventilation in the areas between pedestals is adequate.
  • Aeration spears are a common way for help keep grain cool. They offer a quick, portable and effective way of treating small batches of grain or even be screwed directly into hot spots within a bigger bulk. They do have their limitations in terms of volume ventilated.

To be most effective, air should be passed through grain continuously with good air movement helping to cool the grain even when air temperatures and humidity are higher. Air should never really be felt coming from a stored heap when it is being aerated, this suggests ventilation is uneven with some parts being poorly aerated.

If you have any questions or concerns, contact the FAS advice line at advice@fas.scot or call 0300 323 0161

George Chalmers, SAC Consulting

Related Resources

Crops and soils | Helping farmers in Scotland | Farm Advisory Service (fas.scot)

Crops & Soils Bulletin | Helping farmers in Scotland | Farm Advisory Service (fas.scot)

Barley | Helping farmers in Scotland | Farm Advisory Service (fas.scot)