“There are currently only two methods for planting seed onion bulbs,” explains Emmanuelle Laurent, head of the vegetable department at the French National Federation of Seed Growers (Fnams). “The first method involves simultaneous distribution and planting. A planter opens the furrow, and workers at the back place and position the bulbs. The second method involves first distributing the bulbs on the ground (using a potato distributor) and then manually turning them over. For this task, most farmers need to hire workers. In both cases, it requires about 50 hours of labor per hectare. However, farmers are increasingly struggling to recruit workers for this type of work.” For seed onions, this manual step remains crucial to ensure the crop’s yield potential.
Indeed, onion bulbs need to be positioned with the root plate facing down to fully express their potential. “A poorly planted crop can lead to a yield loss of 20 to 50%,” notes the department head. “This represents a significant loss for seed growers. Various trials have repeatedly shown that improper positioning can have severe consequences. Bulbs positioned sideways result in a 20 to 30% reduction in yield, while bulbs planted upside down (with the root plate facing up) can lead to a 60 to 80% yield loss.”
Despite this, some seed onion-producing regions have completely abandoned the practice, possibly because the farmers did not calculate the potential loss or could not find the necessary labor.
Turning over the bulbs is profitable in most cases
This practice offers several technical advantages for the crop. Turning the onion bulbs over promotes rapid and uniform emergence, which reduces the risk of bulb rot and allows for better weed control, whether mechanical or chemical, due to the uniform stage of the crop.
Additionally, turning the onions prevents lodging, which can lead to harvest losses. These technical disadvantages, when combined, result in economic losses, as calculated by Fnams. “With an average yield of 290 kg/ha of seeds for a hybrid onion variety, and an average revenue of €8,300/ha (including a fixed portion of €4,000/ha), a mere 20% yield loss results in a loss of between €900 and €1,650/ha, depending on the price paid. Meanwhile, 50 hours of labor per hectare, paid at the minimum wage for turning the onions, costs €600.”
Although these figures may vary depending on the sale price of the seeds and the labor cost, turning seed onions over remains profitable in the vast majority of cases. The main challenge is ensuring the availability of labor, which is not always easy...
Mechanization eagerly awaited
Just as the harvest of onion umbels, which used to be done manually, has been mechanized, seed onion growers eagerly await the mechanization of onion turning. With 2,500 hectares of seed onions, making France one of the world’s leading players in the industry, it is only natural to expect solutions from domestic manufacturers.
Two prototypes are currently under development, one by the company Elatec and the other by Seraap. However, these are only prototypes, and no commercial versions are expected anytime soon. The reason is that positioning an onion bulb with the root plate facing down is more challenging than it seems.
Two obstacles stand in the way, according to Emmanuelle Laurent: “The size and shape of the bulbs. Round bulbs are easier to turn than more elongated ones. Some onion varieties may always need to be turned by hand due to their shape. If so, seed companies must ensure adequate compensation. Seed companies will also need to adapt to this mechanization. The calibration of onion bulbs sent to seed growers will need to be more precise to facilitat mechanical turning.”
There should be no illusions. Mechanical turning will not result in savings for farmers, given the investment in equipment. Farmers cannot bear the cost of the equipment investment and the labor required if the bulbs are not sufficiently well-calibrated for mechanical turning. The entire industry will need to work together once a technical solution emerges on the market.