Though non-selective asparagus harvesters are commonplace, the market is also working on selective asparagus harvesting machines. So says Hans Kalter, Sales Manager at Christiaens Agro Systems, a Dutch company that designs and manufactures machines that process elongated vegetables, including asparagus. "We've already introduced 25 of our non-selective harvesters," he begins.
The difference between selective and non-selective systems lies in their harvesting technique. Selective harvesting robot detects the individual asparagus to be harvested, picks it, and places it in containers. Non-selective machines cut the whole bed at once. "The machine harvests the entire bed, soil and all and sieves the asparagus out. The bed is rebuilt under the harvester."
Better quality
"When you harvest by hand, you cut the spears, one by one, pull them out, and fill in the hole. But that spot is always less solid than the rest of the bed. When a new asparagus spear grows, it takes the path of least resistance and, so, grows towards the loosest part of the bed. That results in more crooked spears as the harvest season progresses. They sell those as Class II," says Hans.
"With non-selective harvesting, the beds are rebuilt after the spears are cut and the soil removed. You, thus, have straighter asparagus for the next harvest." Because the asparagus bed is also cleaned, Hans sees that the asparagus has fewer problems with rust.
Capacity
The harvester's capacity is also a factor. "Most growers want to harvest asparagus no more than once every two days, by hand and with the selective harvester. Temperature plays a role here; when it's hot, you must harvest the spears more quickly and frequently. You can moderate the temperature somewhat by using the plastic's white side instead of the black side," Hans explains.
"But when the temperature hits 30+ °C, you'll have to harvest the asparagus daily to maintain quality. With non-selective harvesting, you harvest a few days' worth of asparagus. That means this machine has a high hectare capacity. You can harvest the same plot of land six times on average. You can also use it to flatten a peak in warmer weather. Or to clean up the bed when the asparagus quality declines."
Combination
Hans, therefore, sees non-selective harvesters offering opportunities for several growers. "If it gets really hot and manual or the selective harvesting machine's capacity decreases, the non-selective harvester can provide some relief. After using it, you can rest a plot for up to ten days, depending on the temperatures, and growers can harvest other plots at the right time," he says.
Pre-sorting
However, the non-selective machine cuts all the asparagus, which Kalter recognizes as either an advantage or disadvantage depending on the grower's sales method. "Prices usually drop slightly in the second half of the asparagus season. You pick all the asparagus with selective or manual harvesting, including Class II. And that all goes to market, with the result that the Class II has to be supplemented."
"With the non-selective harvester, the asparagus ends up on a conveyor belt where, at most, four people pre-sort it. Then you can already sort certain qualities in the field, so it won't cost you anything else for an unprofitable product," Hans points out. He, though, also sees growers who could make much more money from selling their Class II asparagus at farm stalls remove all those from the belt.
Regardless, according to Hans, the non-selective harvester saves labor. "You need 1.5 people per hectare, per day to hand-pick white asparagus. To harvest three hectares per day every seven days, you'd need about 30 people for a total of 21 hectares. Using the non-selective harvester, you'd need only four. And using the lights, growers can use them for several hours longer."
Hans has noticed that it is not only large asparagus growers who use these non-selective harvesting machines. "We sell them to companies with, say, eight hectares of asparagus. Those growers can then harvest with no personnel and also avoid the hassle of housing and administration. They work with their own families, for example, using the machine to harvest in the morning and doing the sorting in the afternoon," he concludes, adding that this machine pays for itself in as little as two years, depending on the company's size and sales.
This article was previously published in Primeur May 2025. Click here for the link to the entire edition
For more information
Hans Kalter
Christiaens Agro Systems
Tel: +31 475594869
hka@machiningmatters.com
www.christiaensagro.com