Gardener Rafael Monge sells his harvest directly from his farm in Sanlúcar de Barrameda, on Spain’s Atlantic coast. “I charge for the yellow zucchini, but you get the green ones. I charge a kilo less,” he confides to one of his clients. “You also get spring onions and red onions. Do you know they are the cutest ever?”

The vegetables grow in a so-called “Navazo”: it is a field with sandy soil, almost like on a beach. Although the plants get plenty of sunlight here, they have to make do with salty groundwater, which they absorb through their roots. Groundwater near the coast is always salty due to seawater intrusion. Salt stresses plants, which therefore produce less vegetables. At the same time, however, the plant produces more aromatic substances.

Lower yields, aromatic vegetables

For chef José Luis Fernandez, the courgettes and tomatoes he buys from Rafael Monge are the icing on the cake. “I’m a big carrot lover,” he says. “There is a big difference between Rafael’s carrots and the ones you can buy from any farmer. This one has a salty note, but also sweet at the same time. The skin is very thin, you can eat it.”

José Luis Fernandez grabs the shopping bags that the farmer has filled. That’s enough until next week. The cook is willing to pay the higher prices the farmer has to charge to compensate for his lower yields.

After all, the cook not only gets particularly tasty carrots, tender peas and remarkably aromatic potatoes. In addition, it helps to protect the environment, explains Rafael Monge. “Why should we build more desalination plants or channel water from reservoirs through canals through Olympic-size infrastructure to the coast to grow vegetables?”

Fresh water is scarce

In Sanlúcar, Monge is now the only farmer who still uses salt water. Its approach may seem backward, but it is forward-thinking. It helps retain fresh water. Fresh water is a limited resource. It is already rare in many areas, including southern Spain. There it is transported to the coast with great effort and pumped into the fields, for example into the fields of Monge’s neighbors. They can provide fresh water to their potatoes and get bountiful harvests. The price to pay is high energy consumption and the production of climate-damaging CO2. Fresh water will become even more scarce due to climate change and increased water consumption. Salt water, on the other hand, is plentiful.

If they irrigate their fields sufficiently, Spanish farmers obtain high yields. But fresh water is scarce.© picture alliance / prisma / Raga Jose Fuste

So-called halophytes also grow on the Monge field, surrounded by dunes. They occur naturally in the transition zone between sea and land. “It’s sea chard. I picked a seedling here. The plants also grow on their own on the beach,” the farmer explains, crouching down. “You can eat them. It shows us that we don’t have to fight the sea and salt water. We shouldn’t stop growing vegetables on the beach either, after all, nature does that too.

Salt fields also in Germany

Even in central Germany, plants may have to deal with more salt. This is linked to the fact that farmers are using artificial irrigation more often due to increasing drought and temperatures, says biologist Frank Gaupels. “You can already see that in some areas there is less than 300 millimeters of precipitation, including in Germany, for example in the region around Erfurt. If there is also light soil, you actually have to irrigate in order to use the agricultural land.

It’s also getting drier in the Eastern Harz, Thuringian Lowlands and Upper Rhine Lowlands – a problem that has literally salted itself. “The rain is extremely low in salt,” says Gaupels. But as soon as you use groundwater and surface water from rivers, there is always a certain salt content in the water. “If you use this water for irrigation and in case of high heat, drought and high evaporation, some of the water will already evaporate on the surface and the salt will remain.”

If the rain does not remove the salt quickly, the salt accumulates in the top layer of the soil – and would then be absorbed by cereals or vegetables. So far, the ground in Germany has not yet become salty. Farmers try to avoid the problem by sparing irrigation. Currently, agriculture in this country only has to live in a few areas with a high salt content: on the coasts or near Stassfurt in Saxony-Anhalt, where the salt water from the natural salt domes is located. There, researchers are experimenting with the cultivation of halophytes.

Sea kale, a vegetable of the future?

Frank Gaupels also takes a closer look at these factories at Ökowerk Emden on the north coast. “For example: a sea kale is a plant that can grow well in very saline soils.” The smell of sea kale is reminiscent of white cabbage and the leaves are similar, only slightly thicker. Gaupels and his team also grow salicornia – i.e. sea asparagus – as well as karkalla, the beach or sea banana.

Glasswort is delicious in salads or canned. The wild vegetable that grows near the coast is also called sea asparagus.© picture alliance / blickwinkel / F. Hecker

As part of the transnational project SalFar, the biologist studies how agriculture can succeed with more salt in the soil and water. He works with professionals on the Dutch island of Texel. She is interested in marketing potatoes that receive fairly salty water – like Spanish farmer Rafael Monge. But Dutch potato sales are not doing so well.

“At the end of the day, the potato market is extremely competitive, and there are already many varieties with many different tastes and appearances,” explains Gaupels. “It’s particularly interesting for tourists on the islands, who have read that potatoes are grown on the island, and it’s really local marketing, direct marketing combined with a lot of communication.

In Sanlúcar de Barrameda, chef José Luis Fernandez and farmer Rafael Monge discuss making gazpacho from yellow tomatoes and cucumbers. Vegetables from the salt garden cost the chef more, but he recoups the money because his restaurant’s customers appreciate the more intensive taste and environmentally friendly cultivation.