CULTIVATION AND TECHNIQUE First tests with drip irrigation promising ‘The idea is to map out the cost-benefit ratio of drip irrigation and fertigation both now and in two years’, tells project leader Jacob Dogterom of DLV Plant. has shown that the yields of all the varieties he grows are, on average, 10 to 25 percent higher. The surplus yield can be year dependent. ‘In a dry year, yields are higher than in a wet year.’ Moreover, it also very much depends on the variety, says Dijkstra. ‘In the first year, we started irrigation too late, as a consequence of which the early varieties we grow, such as Agata and Santé, hardly showed any positive response. The later Fontane and Agria varieties showed a surplus yield of around 20 percent that year and Désirée reacted the strongest with a plus of 45 percent.’ Three-year project Dijkstra is not the only one for whom the cost-benefit ratio of drip irrigation is still unclear. In fact, this applies provisionally for all test and practical locations that fall within the scope of the ‘knowledge and innovation network for drip irrigation and fertigation’ in the Netherlands. ‘We intend to have this mapped out within two years’, project leader Jacob Dogterom of DLV Plant says when he’s visiting some of the projects. A three-year project was started last year. ‘We aim to check what possibilities there are to save on the use of water and minerals and what yield and quality improvement the sector can accomplish. This all on condition that the total cultivation system is also economically sustainable.’ Apart from DLV Plant, participants are growers, growers’ organisations, buyers, and government authorities such as provinces and water boards. ‘And let’s not forget the companies that can supply the necessary equipment and chemicals for irrigation and fertigation’, Dogterom adds. These include Netafim, Broere Beregening, Smits Veldhoven, Vos Capelle, RMA Company, Agrometius, Lamb Weston/Meijer, and Yara. ‘Information about expenditure and yield after the first year of trialling is available’, col‘Another positive point of drip water is that the temperature of soil and plants can be managed, not too low and not too high’, says DLV consultant Sigrid Arends during a tour of the various trial plots. league and consultant Sigrid Arends of DLV Plant remarks. Among other things, she is supervising a three-year trial field that is laid out within a potato plot of the Scholtenszathe crop farm near the village of Klazienaveen. A 1.5 hectare patch of French-fry potatoes of the Fontane variety has been fitted out with drip irrigation tubes between alternate ridges. ‘We not only dispense water but also fluid fertiliser via the tubing’, Arends tells us. In addition, cameras have been placed to record the difference between the plots that have irrigation and those that don’t. The trial field also features the customary rain, temperature, and soil moisture gauges. ‘They already provided good results last year and there are also hopeful differences this year’, according to the agronomist. The plus effect is mainly found in the fact that, even during a dry period, the crop continues to grow and receive nutrients. This latter aspect is actually more important, because it improves the quality. Better quality with irrigation From measurements carried out last year by buyer Lamb Weston / Meijer, it transpired that the yield with drip irrigation and fertigation was slightly lower than the yield without irrigation. The quality of the potatoes, however, and also the sizes (more big tubers) were so much better that the returns were ultimately 139 euros higher per hectare. Whether this is sufficient to exceed the drip irrigation and fertigation costs is not yet clear. Farm manager Gert-Jan Heidemans of Scholtenszathe’s reckons that the technology costs and the extra labour are still too high right now. ‘All the equipment originates from greenhouse cultivation where the proceeds per hectare are much higher. At this moment, the total, annual investment costs around 1,000 euros per hectare. By changes in the technology the costs can still be brought down a bit.’ As an Potato World 2016 • number 1 31 Pagina 30
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