When NPPL participant Sjaak Huetink got the chance to try his contractor Goossens Flevoplant’s Poulsen Robovator camera operated intra-row hoeing machine, he did not have to think twice. “The machine was temporarily available because the crops on the other contract plots were too thick to be able to hoe between rows at the beginning of June. At our plots, the plants have a distance of 30 rather than 20 centimeters between them. The machine is very suitable to handle that. By using it, we can further reduce the number of pesticides and labour hours for weeding.”
Both in and between rows
The 3 row machine hoes both in and between rows of strawberry plants that are planted 1,50 meters apart. This distance fits the race, whose vines converge to take root between the rows of maternal plants. 15 employees on weed loungers clear the little flowers with a knife at different stages and weed whatever the hoes do not get or cannot reach.
The same people lay out the vines at a later stage. Eventually, the maternal plants are milled, and the young plants are harvested. Huetink grows strawberry plants for propagation on 30 hectares for Goossens Flevoplant.
After the necessary adjustments and learning to maintain a lower driving speed, employee Martin Smid quickly got the hang of hoeing. “You cannot do me a greater favour than sending me out into the fields with a hoeing machine! Operating the standard machine is good, but this one is especially great.”
He can flawlessly explain how the machine works. “It is powered by a joint shaft and has its own hydraulics and power supply. That electricity is needed for the computer that analyses the images made by its 3 cameras. Each camera has its own light source to ensure a constant environment despite clouds or sunlight. In the terminal, I did however enter the amount of sunlight, the size of the plants and the space around them. Based on that information and the images supplied by the cameras, 2 hydraulically powered hoes are constantly moving in and out of each row. The ‘bicycle wheel’ at the back ensures the machine’s proper levelling through the hydraulic upper link and the reliable measurement of the driving speed. The machine also boasts a substantial hydraulic side shift to follow the rows based on the camera images.”
Constantly refining the settings
After Goossens Flevoplant delivered the machine and demonstrated the first pass, Marcel adjusted the settings as he saw fit. “At first, the machine hoed too many plants, which was mainly due to the high driving speed of 4 to 5 kilometers per hour. I adjusted that to 2 to 2,8 km/h and it works fine now.”
Marcel finds that the settings ask for constant adjustments. “That mostly has to do with the height of the strawberry plants. The cameras detect chlorophyll and therefore do not make a distinction between weeds and plants. The system takes the planting distance in the row (30 centimeters) and the size of the plant as a starting point. When weeds are too large, the machine takes them for strawberry plants and does not hoe them.”
Less chemicals, less labour
The purpose of using hoeing machines and the Poulsen Robovator in particular is to reduce the use of herbicides and the amount of manual labour as much as possible. “Both we and our contractor strive to reduce the use of pesticides, preferably to zero”, says Sjaak Huetink. “Herbicides result in growth loss and weaker plants and reduce the quality of the new starting material. The costs of hoeing and weeding do need to counterbalance this. Normally, we can do 4 to 5 hectares per day with the weed lounger. Thanks to the Robovator, the weed lounger can crank up a notch. They can weed less, and many weeds are already loosened. However, as soon as the vines have grown, hoeing is impossible, and we need to water every day. We can only take stock at the end of July. However, we have never sprayed as little herbicides before and made as few weeding hours. Our plots have never been cleaner!”
Sjaak Huetink (53) and his brother Henri run Huetink Bloembollen in Lemelerveld, in the Dutch province of Overijssel. They rent all the land they use, about 300 hectares annually. They grow 130 hectares of lilies, 100 hectares of first-year seed onions, 30 hectares of strawberry plants, 30 hectares of corn and other crops. They have sown in flowers on the rims of their fields.
