Top tips for successful potato storage this winter

The invasion of Ukraine by Russia, which caused a spike in gas prices, resulted in electricity bills multiplying on many farms and so high energy users, such as potato growers with refrigeration units, have found themselves some of the most exposed businesses in the agricultural sector.

Whilst electricity bills fell in the first half of 2023, costs are unlikely to drop to pre-invasion levels which is prompting farmers and merchants to look again at storage costs. Upgrades and improvements which may have been an overly expensive outlay only a few years ago may now have a much shorter return on investment.

Keeping potatoes in tip top health through the winter storage months requires well-designed sheds with proper air flow and cooling

To this end The Scottish Farmer caught up with Phil Burgess, head of research and consultancy at Scottishpotatoes.org, on how growers could ensure their storage is in optimal condition for some cool and sprout-free potatoes this winter.

Dr Burgess said: “This time last year, many growers and merchants were caught unawares with rapidly increasing energy costs. It was hugely expensive for some of them, depending on when they negotiated their deal with the energy companies and the resulting locked price. The situation is easing slightly now, but still more expensive than it used to be.

“The key thing to come out of all this is that growers now know how exposed they are to price hikes. If there is one positive to the situation it is that most growers now know how much their storage costs to run and they are all looking at ways of bringing those costs that down,” he pointed out.

Four top tips for making the most of potato storage:

1 – Reduce leakage:

One of the most effective and affordable methods of cutting storage costs is to fix the draughty leaks in sheds. Mr Burgess recommended that, over the summer months when sheds are empty, growers turn the lights off and shut the door in their stores. Then look around to spot shafts of light entering the building from where drafts can enter. These are direct air leakages from the refrigerated inside to the outside world will reduce the efficiency in the build.

Dr Burgess said: “It is the same principle with houses where you want to draft proof your doors before putting double glazing in. Potato storage is the same, it is an easy win and affordable. Leaking doors or boards which are beginning to separate will allow draughts of warm air from outside in. A lot of this is common sense but it is quite revealing when you stand in the shed in the dark and see shafts of light coming through. When I was working in the sector around ten years ago we spent a lot of time sorting leakages and it was some of the quickest paybacks on investments.”

2 – Optimise air movement through the store

Growers need to understand the air flow within their shed to ensure an even temperature. Boxes need to have the air flowing through the potatoes not around them.

Dr Burgess explained: “Air will always find the route of least resistance which means when being blown through stores it will avoid going through potato boxes if it can do. I have been in sheds which feel like there is good circulation, but the air is circling around the boxes not going through them to cool the crop evenly.

"There are various things you can do to divert the air such as stacking boxes correctly or setting up air curtains to direct the cool air to where is needs to be. I would recommend any growers who are unsure to contact a specialist who can help.

"A more evenly cooled shed can save money as it is possible to raise the temperature slightly without causing potatoes to sprout."

3 – Insulation:

The more insulation in the potato store the less energy needed to keep it cool. Historically, retrofitting insulation has often been prohibitively expensive but with the higher energy costs the cost/benefit ratio is changing.

Many of Scotland’s potato sores are 20 or 30 years old with relatively poor insulation, so Dr Burgess pointed out that looking again at investing in this could be worth doing.

4 – Upgrade or service equipment:

Many of Scotland potato stores are over 25 years old, with refrigeration units the same age. For some sheds it might be worth replacing the refrigeration system which again due to increased energy bills may be more affordable than previously thought.

One of Mr Burgess’s client recently replaced a refrigeration unit and has cut their energy bills in half.

However, where upgrading equipment is not an option then older machines must be regularly serviced to ensure optimal working. Mr Burgess recommended regular servicing and temperature probes should be checked annually. Growers should test their probes annually by dunking them all in a bucket of icy water at once.

This way growers will be able to assess how close the probes are all measuring the same freezing temperature. All probes which are not measuring correctly should be replaced.

* Scottishpotatoes.org is a collaboration between the James Hutton Institute and SRUC.