CU LTIVATION AND TECHNOLOGY Ten tons extra within five years should be possible with precision technology and cultivation optimisation cept. Usually, during the winter period, we start with an extensive analysis of the soil maps. The analysis is sometimes preceded by a soil scan, but we usually work with open data and also with yield maps. That’s also how we work at Thes Agro. They know that the yield maps have an almost one-to-one relationship with the soil composition. If there are exceptions, for example a section of a plot where the grower knows – for example because of poor harvesting conditions – that the structure is not so good, we use that knowledge for the data analysis. We use all that available information to draw up a yield potential map. The map forms the basis for the various operations during the growing period.’ Up to 10 centimetres difference in planting distance ‘If you grow potatoes, you can use the map right at the start of the cultivation process when planting’, Wilbrink explains. Last autumn, Thes Agro invested in the necessary GPS equipment to be able to plant the seed at varying distances on the basis of the yield potential maps. ‘When we bought our new Miedema planter last year, we were prepared for this new extension and bought a model that was equipped with the latest technology, Van der Wekken told us. Last year, we used it for the first time. ‘We got a yield potential map of the various plots from our precision farming specialist Anthon Slootweg. Together with the agronomist, the map was converted into a task map, which I transferred to a USB stick and connected to the board computer of the planting machine.’ Because of the enormous differences in the yield potential in these potato plots here in BurghHaamstede, the planting distances varied up to 10 centimetres, Slootweg added. ‘We decided to plant at smaller distances in the heavier parts with more growth potential and at larger distances in the lighter spots. Here in the Fontane plot, spacing varies between 25 to 35 centimetres in the row.’ That distance isn’t random, the precision farming specialist emphasises. ‘We specifically looked first at the growth potential of the seed itself. We took samples from all the lots. The seed from these samples were developed in sand from which we determined the number of stems per tuber. Based on that number, we determine the planting distance, while we also consider the total number of seed potatoes we have available for the entire field. The total of all these considerations determines the ultimate distance and variation.’ The beauty of automatic variable planting is that we now also use the exact quantity of available seed, Van der Wekken continues. ‘In the past, we tried to figure out manually how to plant by using a little less in the sandy areas and a little more in the heavier soils. However, the problem was that you always had either too little or too much of the seed you had’d ordered.’ Monitoring growth accurately Apart from variable planting, the GPS system on the planter also makes it possible to variably apply agents such as granulates. Thes Agro also used that possibility. ‘We varied the dosage of the nematode granulate Mocap on the basis of the digital map. If you want to, you can vary these dosages with a sepCOMPANY DETAILS OF THES AGRO Thes Agro is still a young crop farm with a total surface of 625 hectares. The company has three locations spread across the Zeeland peninsula of Schouwen-Duiveland and one in the western part of the province of North-Brabant. The cropping plan of the company comprises the cultivation of consumption potatoes, sugar beet, seed onions, winter wheat, lucerne, grass seed and sometimes blue poppy seed. The total potato acreage is currently 125 hectares. The Fontane, Agria, Ramos and Innovator varieties are grown for the French-fry industry. Crop rotation is currently 1:5 and that enables a change to 1:4. Thes Agro works solely with its own machinery. Three of the four farm locations have their own potato storage facilities to avoid having to transport the potatoes over long distances. The total storage capacity is 5,500 tons, which is not sufficient to store all the potatoes. The total yield of the Innovator variety is therefore sold directly from the land in September. arate task map’, according to Van der Wekken. When walking through the potato field, you can hardly see where the seed was planted at smaller or larger distances due to the gradual transition between the zones. ‘I would have to check the task map for that’, the Thes Agro man laughs. Now that the potato plants have just emerged, we need to monitor their growth accurately during the rest of the growing season. ‘In the TT concept, this is the next step. Monitoring includes things like taking soil samples to determine the availability of minerals and, naturally, also the measuring of the uptake of nutrients in the plants themselves. By linking the resulting data to the yield potential map, the task map that this produces can be used again for controlling the field crop sprayer or the fertiliser distributor. Another thing is that you can vary pesticides and fertiliser in relation to the yield potential of each part of the plot’, Slootweg says. ‘I still remember how we used to work in the past: just spread a bit of extra fertiliser on that sandy spot, because the crop there can use some more. We now do the reverse, give a little more on the heavier soils, because that’s Potato World 2017 • number 3 37 Pagina 40

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