Seed potato grower says goodbye to inspection room CULTIVATION AND TECHNOLOGY the current procedure. What becomes clear is that, up to now, grading has always been a specifically-manual procedure. For example, think of the squaregrid sizer with its rough grading. Two generations ago, the 35 to 55 mm square grid was introduced in order to put 750 tubers in a 50 kilogram bag. This was a shift towards the practical situation of the seed potato grower. Nowadays, many potatoes are transported in bulk. We are now digging into the box to estimate the number of tubers. Gradually, we’ve discovered that the grading in a lot can fluctuate enormously. This means that we’re getting undersized and oversized tubers in the box or big bag. There are, on average, 19,000 tubers in a box. Two percent under or oversize in a lot may mean about three hundred tubers fewer or more. Maybe the inefficient sizing means fewer potatoes to plant so less return on investment. There are tools to help us such as GPS and now also electronic grading. I’m certain that we’ve suffered delays in our development as a sector, because we don’t really understand it because of the large square-grid sizing. We’re talking about precision farming, validating satellite maps with AB lines and things like that. But we’ve never validated the yield measuring’, says Broeders. Up to 50 percent deviation in traditional grading systems Research by Miedema trainee Jack Simons of Wageningen University shows that there can be as much as 50 percent undersizes among the oversizes. He underpins his allegation on the basis of samples of precision and jump grading machines of various makes. He has manually checked the various gradings. ‘In a Spunta lot, over 50 percent of the >55 size was really 35-55. After grading, this lot had roughly 10 tons of oversized spuds per hectare; if grading had been accurate this would have been halved to 5 tons per hectare. Last year, the price difference between these sizes was over 20 euro cents per kilogram, which means a loss of profit of over 1,000 euros per hectare’, Simons, himself the son of a seed potato grower in West-Brabant, calculates. ‘This kind of result puts you on the wrong track’, Broeders adds. ‘Let’s look at how the time of haulm killing is determined during the growing season. Growers take weekly samples for that. We lift a few yards in a plot, grade them per tuber and then process them in big grading categories 28-35, 35-45, 45-50, 50-55 and 55+ mm upwards. If a lot is close to 55 mm, you need to work differently to lift the seed in an optimal way than when a lot has only just gone past 50 mm. That’s the reason why Sijtsma is also going to use the new machine for lifting test samples to collect data to determine the correct moment of haulm killing. ‘It’s amazing how much they keep on growing after haulm killing. You need to take that into consideration when you’re processing the samples. That’s the beauty of data collection, that you can compare over the years. Make improvements and measure now, and you get to see a lot of things. When you measure the entire lot, you get 100 percent reliability. As a result, you start thinking again about the processes. With the introduction of the Smart Grader, seed potato growers can provide customised products based on the wishes of the customer. If you know more, you get a different discussion’, Miedema’s Marcel Mulder says. Sustainable work ‘When you look at the seed potato chain, you see that the mistakes are costly’, knows Broeders. ‘Logistic and delivery mistakes make it even more expensive. I think that you can make the biggest savings right at the beginning of the process: the seed potato grower. Step 1 in this – register the current processes correctly. Where is my waste, what are the costs of errors, and how can I minimise them? Step 2 – in the logistic and commercial processes, decide what you will do with this information, or how will you offer what you have . And ensure that this is also sustainable, because a grower uses his land as effectively as possible and because he delivers the maximum yield in the desired size. Today, when the fight for clean-seed potato soil is still ongoing, this is a challenge. When you plant accurate sizes, you’ll have an optimum division in the ridge and a better distribution of the stems. Communicate the number of tubers An additional advantage of the machine is that it can count the exact number of tubers. ‘You know from every bunker lifter how many tubers it contains. So when the bunker lifter is empty you know how many tubers there are in a box. We’re also going to give this information to Kroef, so that the consumption growers can be told what to expect’, Sijtsma says. ● Jaap Delleman An additional advantage of the machine is that it can count the exact number of tubers. Potato World 2013 • number 2 27 Pagina 26
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