Smart Farming is still a matter of trial and error CU LTIVATION AND TECHNOLOGY ‘We see high-tech equipment,’ explains Herman Krebbers who, as a hobbyist, likes to experiment with drones himself, ‘but that won’t help you if you don’t have any background knowledge of your crops and plots. and look at it with your eyes before starting with measuring equipment.’ The advisory officer also has a striking example which proves that you don’t always need instruments to carry out measurements and that, in such cases, Smart Farming techniques don’t add a lot. It concerns the results of a trial plot with seed potatoes with three nitrogen start applications; 30, 60 and 90 kilograms per hectare and a benchmark. At a later time, each plot was fertilised with 11, 55, 81 and 97 kilograms of nitrogen per hectare respectively. At the end of the growing season, it appeared that the yield within the 25 to 50 mm sizes were virtually the same in all four fields and was around 30 tons per hectare. How is that possible is the question. ‘Quite often the reason for crop differences can be found in the soil: in this case, for example, there were already sufficient minerals in the plot.’ Many variations within a plot It’s not for nothing that Krebbers gives this advice, because the participants in the Agriculture 2.0 High-tech Sensing project in Zeeland have come to the same conclusion over the past two years. Delphy advisor Hans Moggré gives a striking example of this at the Kamperland symposium. On an 8.25 ha plot of consumption potatoes, after leaf juice tests at three different times and in three different field locations, it transpired that the nitrogen application was ultimately not related to the yield. And yet, there were differences between the chart images and the measured yields, what could be the reason? was the question that naturally came up. Now, not only the kilogram yield was recorded, but also the underwater weight, the P level in the soil, the lutum percentage and the percentage of organic matter. What’s remarkable is the big difference between the figures. There’s a lutum percentage of only 4 percent. ‘This means it’s really difficult to give a nitrogen application before planting’, Moggré observed. In the tested plot, the soil and the P level appear to have more influence on the yield than the nitrogen application. The conclusion that can be drawn from this practical case is that it’s much better to vary with potassium than with nitrogen. Moggré is not afraid to extend this advice to many other practical situations. He argues that ‘within the present fertilisation levels, nitrogen isn’t the determining factor for yield variations within a plot. And that’s what we were focusing on in the first years of applying satellite images’, the advisory officer acknowledges. He further concludes that ‘the potassium level can vary a lot within a plot. For potatoes, that’s one of the reasons for the enormous differences in underwater weight.’ No quick conclusions Another lesson to be learnt from the first practical experiences with Smart Farming in Zeeland is that you shouldn’t draw conclusions too quickly from the Potato World 2016 • number 2 31 Pagina 30

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