is that possible? First harvest is disappointing, but scientists are undeterred

Last year, scientists planted 3,000 rice plants on peat soil near Leiden. The experiment hardly yielded anything, but new rice plants are still being planted this year. Because researchers are still hopeful that it is possible to grow rice in the Netherlands and also put a stop to major problems such as soil subsidence, salinization and declining biodiversity.

In the spring of 2023, scientists planted 3,000 small rice plants in a peat area near Leiden, hoping that they would grow quickly and the first ‘polder rice’ could be harvested in September. However, it did not get that far. After a good start – with the rice plants growing well and looking healthy – a cold wave during the flowering of the rice plants threw a spanner in the works. The cold snap caused sterility of the rice flowers and only 1 percent of them developed into rice grains.

New attempt
However, the failed harvest does not stop researchers from trying again. Scientists are currently planting rice plants in the Dutch polder again. “This year we are planting 32 rice varieties,” says researcher Maarten Schrama. “Including from Japan, Russia, Uzbekistan, Italy and Sweden. There should be a few rice varieties that will do well.”

Solution to big problems
It is easy to explain why the researchers are persevering – despite the failed 2023 harvest. On paper, the cultivation of ‘polder rice’ can yield much more than just food. In theory, by growing rice on peatlands we could also combat soil subsidence, salinization and even CO2 emissions and actually increase biodiversity.

How exactly does that work?
The rice is grown on peat soil. That is ground that is quite low; below Sealevel. Normally, this peat soil is often used as pasture land. However, this requires that excess water be pumped away so that the water level remains below ground level. But that approach causes the bottom to sink. “Because we pump peat – in fact nothing more than plant remains – partially dry, oxygen can be added and the peat decomposes,” explained researcher Aart van der Linden already off last year “And when peat decays, the soil sinks. In some places in the peat meadow area the decline is as much as 10 mm per year. If you also consider that the sea level is rising by about 3.5 millimeters every year, you understand that this subsidence is difficult to sustain.”

And that is not the only problem that pumping peat areas dry – and therefore the decomposition of peat – entails. “When peat is broken down, CO2 is also released.” This concerns carbon that the plants that make up the peat have absorbed from the atmosphere a long time ago. As long as peat is under water, carbon is safely locked up. But when we pump the peat dry, oxygen is added, which allows the plant remains to decay and the CO2 ends up in the atmosphere and contributes to global warming. In short: our current use of peat soil has several disadvantages and is not very sustainable. But all these disadvantages disappear like snow in the sun if you no longer use peat soil as pasture land, but instead use it for rice cultivation. “If you start growing rice, you can raise the water level,” says Van der Linden. “Because rice likes wet feet. This way you protect the peat underneath.” It remains wet and therefore does not decay. And this means that the soil no longer subsides and CO2 no longer leaks from the peat. In addition, seawater intrusion and salinization are prevented. “Because the water level in these low-lying peat areas is raised, salt water cannot penetrate further into the land.” In addition, similar experiments in northern Switzerland – where risotto rice is now grown in peatlands by several farmers – hint that rice cultivation can increase biodiversity. In short: rice cultivation offers great opportunities for the Dutch polder. And so researchers will simply try again this year. They will of course take with them all the lessons they learned in the first, disappointing harvest year.

In the Dutch rice field that is currently taking shape, not only various rice plants can be found; Researchers will also soon release fish there. For example, they release the African catfish. The poop of this fish forms a natural fertilizer for the rice plants. The fish also protects the rice plants by eating weeds and bugs. And when the rice is harvested, the fish also heads for the plate. “We already experimented with it last year,” says Schrama. “The fish then went to a fish smokehouse in Roelofarendsveen. They taste delicious.”

Large scaled research
What the new year will bring in terms of rice and fish remains to be seen. But researchers still see a lot of potential and are determined to find out whether and how they can capitalize on it. Whether it will ultimately be a success does not only depend on how much rice is harvested or how many kilos of fish are fished from the rice fields. The researchers really want to look at the whole picture and therefore find out whether rice cultivation is a really good and sustainable alternative to the current use of peat land. For this purpose, CO2 emissions will be examined, among other things, Van der Linden said earlier. “You don’t have to import rice that you grow yourself. So that saves on transport and the associated greenhouse gas emissions. In addition, less CO2 is released from peat soil by growing rice. But at the same time, wet rice cultivation does release methane – a very potent greenhouse gas.” The question is therefore whether the CO2 savings – through less transport and keeping peat soil wet – outweigh this. “It should of course be noted that cows – which now walk around on drained peat soil – also emit methane, so for a complete picture we should also take the emissions of those cows into account if we want to determine whether growing rice is more climate-friendly. ” Biodiversity research and of course research into the economic feasibility of polder rice are also still planned. And there are even anthropologists and social scientists involved in the experiment, Schrama says. “Because how do you change the deep-seated tendency to leave everything exactly as it is? The fact that the image of the landscape is going to change is unpalatable for many people.”

Whether the traditional Dutch landscape will ultimately change so much will of course depend greatly on the data and results that researchers will collect in the coming years. But we certainly do not have to expect that Dutch fields and pastures will soon be transformed en masse into rice fields, as Van der Linden previously predicted. “I think it will remain a niche market, with a few hectares of rice here and there. But at the same time it cannot be ruled out that in the much longer term, if all developments continue and the water level in the peat meadow areas really has to rise, rice will play a significant role and become an important crop at least in the lowest parts of the Netherlands. is becoming.” Time will tell.