The problem is the solution: salty soils

Irrigation and fertilisation are two ways that soils can become salty. We’ve known this for a long time and have failed to do much about it. It’s estimated that about 20% (45 million ha) of irrigated land, producing one-third of the world’s food, is salt-affected. Soil salinity reduces the yields of most of the cereal, legume, and vegetable crops that we currently grow. This is mainly due to increased soil osmotic pressure and interference with plant nutrition due to, for example, ion competition. If you want to read more about how soil salinity effects plant growth, then this is a good place to start.

Quick solutions: reduce the need to irrigate through the use of shade trees (agroforestry). Increase water infiltration and reduce run-off with keyline systems, swales, etc. Limit the amount of synthetic fertiliser needed or eliminate the need altogether by the use of N-fixing plants, cycling fertility back to the fields, and good animal husbandry cycling manure around the system. We know how to sort this problem out. We just need to get on with it.

Rising sea levels

This is the main theme of this article, what are farmers supposed to do faced with sea-level rise, coastal flooding, and salt-intrusion? We have sea level rise and excessive groundwater pumping contributing to saltwater intrusion into aquifers. The underground fresh water gets salty, if we use this to irrigate standard crops we exacerbate soil salinity. Researchers from the Institute for Environmental Sciences (IVM) at Vrije Universiteit Amsterdam estimate that salty soils will impact around 13 million farmers. They don’t specify the number of farmers already impacted. They do mention how this leads to farmers having to adopt a sort of fight or flight response. Some stay and try to adapt, others flee.

Back in the day, we domesticated both the animals and plants that were the most easily domesticated. Over the millennia we have narrowed this down to today where most calories come from rice (staple for +50% of the global population), wheat (35%), corn/maize, soybeans, sugarcane etc all combined provide most of the calories that we humans consume. Alongside these ‘big players’ are thousands of other crops, some are little used, some have come back into fashion, some are still valued by local people.

An example of a plant that has come back into fashion around here and elsewhere is Allium ursinum, ransoms. For years I was the only one who went to harvest it, 2 years ago I arrived at my favourite spot to find that they had all been taken. Sometime after that a friend told me that you could now buy ransoms plants in the local garden centre.

Back to the main thread, there is a long list of list of halophyte (salt-tolerant or salt-loving plants) that grow around the Mediteranean basin. You can find it here, Edible halophytes of the Mediterranean basin: Potential candidates for novel food products.

Some of these plants are xerophytic, they can thrive despite very low levels of soil humidity. Useful in a heating world and one which is experiencing more and increasingly severe droughts.

We have a range of edible halophytic plants that can be eaten as salads, cooked as leafy greens and conserved (for example Salicornia herbacea, grasshort in vinegar). Shrubby seablight (Suaeda fruticosa Forssk) is a salt hyper-accumulator and can be grown to reduce soil salt load. If you like your food spiced up a bit then Pepperwort (Lepidium latifolium) can do that for you, the seeds that is. The young shoots and leaves can be eaten and the seeds dried to use a pepper substitute.

If we continue to think in terms of yields, tonnes per hectare, then these crops don’t compete with our staple ones. If however we think of food as being about nutritional content and taste then they out-compete conventional crops. Spring 2025 in Europe and the UK has been relatively mild and there is already an abundance of vegetables coming to market. These crops have been produced under polytunnels, the seeds used are ones adapted to high levels of fertiliser inputs and the plants were developed to grow and mature quickly. This means that the crops have lower nutrient density and less flavour than open-field crops. If we compare polytunnel/open field with wild halophytic plants then the latter win hands-down.

How can we encourage consumers to adopt novel crops?

People tend to be conservative when it comes to food, we conserve a taste for those things we were given to eat as children. But we also, occasionally, try new stuff. So, marketing, for a start these foods aren’t novel, they are traditional which is a good marketing point. We meet people who introduce us to new things and we try them because it’s rude to say ‘no’. Sometimes we like the novel food and adopt it. We eat out and sometimes we’ll go to a new restaurant and try something different. Then of course there are the TV shows and influencers, either of whom can encourage us to widen or diets.

It would be possible for us to leverage (I think that’s the correct use of leverage) all of the above to encourage one and all to diversify their diets. If we can adopt halopytic plants back into our diets then we’ll have created a market for farmers with salinated soils. They can produce sea-beet instead of the usual cultivated ones, sea-fennel instead of fennel, or maybe Cardoons?

If you feel like drilling down further then these people have done some interesting work. Exploring the Potential of Mediterranean Edible Halophytes as Novel Crops: Ecological and Nutritional Insights from Tuscany’s Salt Marshes