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Selective harvesting involves picking parts of the crop that are ripe, without damaging parts of the crop that need to be harvested at a later time or left in the soil. At the moment, this technique is only carried out by hand. Typical examples of selectively harvested crops include tomatoes, cucumbers, strawberries, melons, blueberries and raspberries.
“This is also the case for white asparagus," says SPARTerS project coordinator Thérèse van Vinken of Cerescon in the Netherlands. “The European market is currently worth about EUR 800 million a year, but unfortunately the entire industry is under threat. This is partly because the number of hand pickers is declining year by year, while the price of manual labour continues to rise.”
There are other issues associated with hand picking. Asparagus spears can sometimes go undetected and be left sticking out of the sand bed for the next harvesting session. This can lead to discolouration and the asparagus developing open heads.
Automated harvesting solution
To address these challenges, the EU-funded SPARTerS project has focused on bringing to market a mechanised selective harvesting machine. The key aim of this innovation is to lower asparagus harvesting costs, as well as improving the quality and quantity of the crop.
“The solution is based on a patented underground detection method,” explains van Vinken. “Sensors detect the asparagus as it grows underground, without coming into contact with it. This means that the crop remains undamaged.”
At this point, data on the asparagus is transmitted to a patented self-propelled harvesting robot. The robot picks only the asparagus that is ready to be picked in one single movement, placing it on a conveyor. The hole left behind in the sand bed is then repaired, to prevent the next crop from growing curved.
Trials have shown that using the Sparter machine can cut the cost of harvesting by half, in part from savings on labour costs but also because the crop is not damaged and there is little wastage.
“All kinds of data can be collected from the underground sensors,” adds van Vinken. “This can help ensure that crop yields are more predictable.” For example, farmers can be made aware of the need for fertilisation or irrigation at a certain time, or in a certain area of the field.
Asparagus growers have been instrumental in the development of Sparter from the beginning. “We formed a UserGroup, made up of growers in the Netherlands and Germany,” explains van Vinken. “These farmers provided extensive feedback on the development of this technology and have also been important in providing us with information on their specific requirements, facilities and picking costs.”
Future of farming
Van Vinken believes that the Sparter innovation represents the future of asparagus farming, especially in light of the coronavirus epidemic. Growers, heavily dependent on manual labour to tend their asparagus beds, were left in crisis after borders were closed.
“Selective harvesting in western Europe is usually carried out by temporary workers who come from abroad,” explains van Vinken. “As many of these workers were unable to travel, farmers were unable to tend their crops. In some instances, between 70 and 80 % of asparagus beds were left unharvested.”
Another point is that manual white asparagus harvesting is heavy, physical and demanding work. Transitioning to automated selective harvesting promises to create more skilled and better qualified jobs that focus on machine operation and sorting. Despite the challenges the sector faces, Europe still represents almost one third of the world's asparagus market. Van Vinken is confident that this remains a lucrative market that can be built upon and improved with the application of technology. Indeed, SPARTerS is definitely leading the way – due to the success of the EU-funded project, the project team have also recently received an additional EUR 3 million from private sources to continue their work.