Training is key to keeping skills and knowledge up-to-date. For the first article in a new series exploring training and professional development opportunities in the arable sector, Heather Briggs attends a potato store manager’s course run by the specialist team from Sutton Bridge Crop Storage Research (SBCSR).
Crops are often in store longer than they are in the ground, so maintaining crop quality in storage until it is delivered to customers is one of the crucial concerns of store managers. Investing in training, therefore, makes sound business sense.
Storage needs to be viable, efficient and cost-effective, said Adrian Cunnington, head of SBCSR.
Potatoes coming out of storage have to meet customer quality specifications or be threatened with rejection. Having the ability to identify and assess threats and predict what happens next in storage helps make the right decisions to keep tuber quality consistent.
Challenges include tuber weight loss from evaporation, cell breakdown from defects and diseases and efficient sprout prevention.
Mr Cunnington said: “There is no magic formula for crop storage. Every store is different, so optimisation depends on making the right decisions at the right time.”
Different end markets need different storage conditions: ware (fresh-pack potatoes) need colder temperatures to keep them dormant; and processing potatoes need to maintain higher sugar levels for fry colour which can be damaged by colder temperatures.
Bulk stores are generally favoured by the processing market, while ware growers often prefer box stores, but both types of stores present benefits and challenges, he said.
Condensation is one of the major threats to in-store crops, as it creates an environment for disease proliferation, so ensuring even ventilation throughout the store is key.
Mr Cunnington said: “Loading stores correctly, whether they are bulk or box, makes a big difference to air-flow.”
In box stores, stacks should be correctly oriented for optimal air distribution, he said.
Tubers come in warm from the field and need to be cooled; knowing how fast to bring down temperatures is also important; too fast and condensation occurs, while too slow may speed up disease development.
But it is more complicated than that. Although most potato diseases proliferate more quickly in warmer conditions, others, such as skin spot-susceptible varieties, need the crop to be ‘cured’ at warmer temperatures to allow the potato to heal itself before temperatures are lowered.
Mr Cunnington said: “When you need to bring down temperatures quickly, the secret to avoiding condensation is to ensure the difference between store temperature and tuber temperature is not more than 4degC.”
Many diseases come in from the field, and the longer the plant has been in the ground, the greater the chance of disease occurring.
Knowing the market and tolerances helps drive decisions on which crops should be unloaded first, said Dr Glyn Harper, crop pathologist at SBCSR.
There are a number of factors affecting disease present in the field then being carried into store. These include:
Dr Harper said: “Most blemishes and diseases can be distinguished visually, so a good sampling strategy is a must. If you know what is coming in from the field, you can devise a strategy for dealing with it.”
He also recommended frequent store monitoring to assess changes, particularly as some diseases are not visible and only develop later.
“Accurate assessment of which potatoes to take out of store is crucial for the well being of the business.”
Although there are a number of sprout suppressants on the market, chlorpropham (CIPC) remains by far the most used.
Best practice has been recommended by the CIPC Stewardship Group, but store managers still need to consider whether to put on one application when the crop goes into storage, or repeat applications.
Decisions should be based on:
The secret to success is to prevent condensation, so a well-designed store design which promotes stable temperatures and air circulation is cost-effective, said Mr Cunnington.
Investment in ventilation, with the use of frequency drivers or inverters, paying attention to airflows, refrigeration compliance and using energy saving appliances, all makes sound business sense, he added.
Any leakage of air is a threat to tuber quality and should be rectified as soon as possible. Moreover, as ventilation equipment compensates for leakage, this can soon result in high energy charges.
Mr Cunnington said: “We need to make our storage viable, effective and efficient, so we need to invest in storage as much as we do in machinery.”
“Post-harvest training appears to be second tier across most of the world. Agricultural courses spend a lot of time and energy teaching about coaxing the crop to get the best yields, but it is really how the crops come out of store which can make or break a company.
“There is a huge gap of information for store managers. The next generation need to know the latest techniques.
“Many onion and potato crops spend more time in store than in the ground.”
Dirk Garos, director of Restrain Company
“You never finish learning, so further knowledge is always going to be interesting. There is a lot to learn about sprout suppressants, such as chlorpropham, and their applications.”
Catherine McNeil, Spearhead Marketing
“There are lots of changes going on in the industry and different methods for tackling problems. Success in-store means you have to make decisions on store design, temperature stabilisation and the crop holding period. There is no right or wrong answer, it is all to do with what suits your business.”
Dan Allwood, trainee store manager, Hay Farming
“There are a lot of decisions to be made about how to control crops going into store. Bringing people together is a good idea because discussing options can be really helpful.”
Philip Thompson, E.C. Drummond Agriculture
“Fry colour is key to the processing sector and there are lots of variables to take into consideration. Knowing exactly what procedures to take when there are variations are crucial.”
Richard Hinton, Wolds Produce