#FrontierWest - Long term grain storage and calculating tonnage


We are now over half way through the marketing year, with harvest '18 in our sights. I am based out of our Ross-on-Wye Frontier office, farm trading in the West and with our grain markets still at relatively static levels this has sparked more focus for long holders to start securing end markets for old crop grain.

Many growers across the three counties opt to store their grain long term. This avoids selling at harvest, a typically discounted period and takes maximum advantage of price carry and potential rallies. Although there can be price benefits to holding your grain on farm, there is also an increase in risk to grain quality. This can lead to premium loss through claims or rejections and expose risk along the supply chain.

At this time of year in particular, grain that hasn't been moved since harvest needs monitoring to avoid any moisture increases, moulding areas and growing hotspots. For all grain, the main causes of spoilage come from insects, mites, fungi and particularly rodents in the winter.


When selling grain, the impact of insects can cause significant issues for all parties involved.

The two most common species that infest grain are grain weevil and the saw-toothed grain beetle. The grain weevil starts by developing inside the grain, making early detection difficult. However, the presence of one species can lead to a succession of others, some of whom can develop outside the grain itself and require broken grains to feed from. Although grain weevils breed at relatively low temperatures, they can develop 'hotspots' and raise grain temperatures locally which encourages the likes of saw-toothed grain beetles and mould-feeding beetles to breed, as well as mites and booklice.

AHDB recommends that the "Correct identification of pests found is important. Traps within the grain bulk should be positioned both on the surface and approximately 5-10cm below the surface to monitor for pest species with different behaviours." To help, you can refer to this Pest Identification Sheet

Moisture and temperature

Moisture and temperature are two key factors that, if unmanaged, can encourage an environment suitable for grain spoilage to occur. Poor management of these two factors can lead to OCHRA toxin formation.You cannot see this formation, but if you have this issue you are legally not allowed to blend. Here are some important points for good practise in long term storage:

Moisture should be managed from harvest and targeted below 14.5% for cereals and 7.5% for oilseeds.

To proactively manage moisture levels, you should:

  • Monitor at several locations (same each time)
  • Record at least once each month during winter
  • Allow a safety margin: errors are frequently ±0.5% and can be greater in very wet, very dry or freshly harvested grain.

Temperatures should aim to be below 15°C within 2 weeks of storing, then target 12°C within 3 -4 months and thereafter 5°C.

  • Monitor weekly until target reached and fortnightly thereafter
  • Record at the same location every time
  • Take measurements where cooling takes the longest e.g. furthest from fan in blowing system
  • Temperatures should be taken 0.5m beneath surface.

Sourced AHDB Grain storage guide for cereals and oilseed Third Edition

For additional support, you can access these key grain storage and sampling tools from AHDB, including the Grain Safe Store Calculator.

Whilst maintaining quality is one challenge, estimating the quantity in store is another. Overselling on contract can be a costly situation for growers. To help avoid this there are measurements you can take and a calculation that came be used to estimate the tonnage. Use the average bushel weight score and this table, followed by this equation:


  • 1.Length x Width x Height = 'Xm3'
  • 2.Review the estimated bushel amount in the table and find the cubic metres per tonne associated with that bushel.
  • a.For example, a 75kg bushel equates to 1.33 cubic metres per tonne.
  • 3.Divide your first figure (L x W x H) by your cubic metres per tonne.
  • a.For example, if L x W x H = 200m3 and your bushel is 75kg, you would calculate 200 divided by 1.33 – 150mt.

If you would like any more information on grain storage or help estimating your tonnages please contact your local Frontier grain expert.

Victoria Godsall
Farm Trader

For specific advice for your business related to this blog or any other aspect of crop production get in touch with Frontier. 

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Thursday, 11 August 2022

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