Smart Farming is still a matter of trial and error CU LTIVATION AND TECHNOLOGY various chart images. ‘You should first have an overview of all the data’, advises Moggré. He advises first to run a soil scan, carry out yield measurements, and examine the soil thoroughly. The fact that the latter is especially important is clear from the experiences shared by advisory officer Nelis van der Bok at the symposium in Zeeland. ‘Aerial photographs and satellite images can also be a pitfall’, he shows his Audience. The example he uses is an image of a potato plot on the Novifarm crop farm in Numansdorp. ‘What we see is variation and our immediate thought is: let’s get busy with the nitrogen. But, in many cases, applications of nitrogen are mostly just treating the symptoms. That’s what we also found here.’ As soon as we saw that nitrogen variation didn’t have any influence on the yield, we had to look for another reason. ‘What those photos show is biomass. There are other factors besides nitrogen that determine its apparent density.’ Van der Bok sums up: the organic substance content, the presence or absence of nematodes, soil structure, the various nutrients, moisture supply, soil profile, acidity (pH), salinisation and weather conditions. If these factors are involved, the standard satellite and aerial photographs seldom provide sufficient information. Van de Bok demonstrates this with images from thermal cameras, which show a bluecoloured area within the plot. Blue ‘GPS is an aid. It will never be a determining factor for the result’, is Leo Noordam’s conviction. means that the temperature is lower there and indicates the presence of moisture. The image was taken during a period of drier weather. This wasn’t visible in earlier photographs, because the soil was wet everywhere due to rainfall. The only remaining question is: why is that spot cooler? The answer comes from a different measurement, from a relief map, which shows that that area is 30 cm lower than the rest of the plot. It appears to have been an old meadow and that information was found on a very old topographic map. Incidentally, those maps can be consulted on the internet free-of-charge, via the website, for example. What does this teach us? ‘If you had collected data prior to the satellite and aerial photographs, you could have concluded that the moisture supply in the old meadow was much better than in the other parts of the plot and that the nitrogen uptake by the plant was also much better and so the nitrogen application could have been lower. With GPScontrolled technology, you can then apply fertiliser in specific spots’, Van der Blok explains. During his talk at the National Seed Potato Day in Emmeloord, Leon Noordam, joint partner at Novifarm, tells his Audience that he also found it difficult sometimes to interpret the results of the chart images correctly during his first years. ‘When we get a picture from a sensor and we don’t know what happened in the past, we can sometimes get the interpretation wrong. For example, it’s already very difficult to determine what the effect of extra nitrogen can be, or the variations within a plot. What we’ve learnt is that we still have to go out into the field and can’t leave everything to our equipment. Take samples of soil and plants, count stems, in short, follow the growing season carefully with your own eyes; this is and will always be important. GPS is an aid. It will never be a determining factor for the result’, is Noordam’s conviction. ● Via the www.topotijdreis.nl website old plot maps, which can provide useful information about the soil (the past) of a potato plot, can be downloaded free-of-charge. Leo Hanse Potato World 2016 • number 2 33 Pagina 32
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