Finding what’s possible

Farmer-ecologist Maarten Schrama at Oude Ade: ‘Despite the presence of invasive crayfish, part of the ditches is now crystal clear.’ PHOTO: LEIDEN UNIVERSITY   Agriculture and nature need not be mutually exclusive, believes ecologist Maarten Schrama. In his academic career and beyond, he explores what is possible.

‘When we started this project, the area offered ample opportunities’, ecologist Maarten Schrama reflects with a proverbial wink on the launch of the so-called polder lab in Oud Ade. In collaboration with the citizens’ cooperative Land van Ons, the regional authority Holland Rijnland, and interested farmers, Schrama and his colleagues at Leiden University have been conducting large-scale research into various forms of nature-inclusive farming in this ‘living laboratory’ since 2021. ‘We are looking for alternative agricultural models in which farmers can continue to produce whilst the peat becomes wetter and more biodiverse’, Schrama emphasises. ‘We are also investigating whether it is possible to make the peat rise again rather than subside.’

  Rice ‘Although we have left part of the grassland – which consisted mainly of perennial ryegrass – untouched, the vegetation has increased enormously within a few years and become much richer in plant species’, Schrama explains, ‘purely through a different fertilisation and mowing regime.’ The part of the plot divided into test plots has, understandably, undergone even greater changes. One of the most striking experiments is the cultivation of rice, an unusual crop in the Dutch peat meadow landscape. ‘Last September we were able to bring in the third harvest’, Schrama says enthusiastically. ‘We have harvested many kilograms of rice, not only from the polder lab field, but also from test plots in surrounding polders. The plants grow well, the grains ripen nicely and are marketable.’ Schrama and his team will shortly have the rice tested for heavy metals. ‘Low values are interesting for farmers, because that means the rice can enter a higher crop segment’, he says.

  Sphagnum moss Alongside the rice fields lie new sphagnum moss plots, on which living sphagnum moss and cranberry bushes are growing, both with production goals in the longer term. This has been successful so far: the paper-thin layer of sphagnum moss that the polder lab received at the start of 2024 from the Nieuwkoopse Plassen has grown in some places to as much as 10 centimetres thick in just eighteen months. This is remarkable, because cultivation is not without its challenges. Schrama explains: ‘Sphagnum moss, like cranberries, thrives on wet, acidic soil. Water flowing into the Netherlands via the Rhine is, in fact, quite alkaline. That need not be a problem, because a flourishing sphagnum moss area is so wet that water flows out of it rather than in. However, due to large-scale drainage and the currently low groundwater levels – up to a metre below the surface in summer – that does not apply here. In dry periods we therefore use specially acidified water.’  

In addition to being an ecologist, Schrama also calls himself a part-time farmer

  Raising the local water level by a few centimetres per year turns out to be insufficient to keep the peat wet. ‘The groundwater level in the fields barely rises as a result’, Schrama explains. ‘We are therefore now working on infiltration trials using small ditches – comparable to drainage ditches, but designed to bring water into the fields rather than carry it away. That appears to be working very well. We are also looking, together with Radboud University, at possibilities for organic water filtration systems to purify the water before it enters the polder.’

Crystal clear Water quality in the polder ditches has improved considerably in recent years. Schrama explains why: ‘That is largely thanks to the reintroduction of native aquatic and bankside plants by our aquatic plant farmer. We can see that the condition of the water is improving in leaps and bounds thanks to plant species such as water soldier and bladderwort. These thrive perfectly well, despite the agricultural use of the adjacent land and the presence of invasive crayfish that feed on the aquatic plants. It came as something of a surprise to us as well, but part of the ditches is now crystal clear.’

  In addition to being an ecologist, Schrama also calls himself a part-time farmer. Together with Jan Degenaar, he is co-founder and co-manager of Voedselbos Haarzuilens, near Utrecht. This covers some six hectares with now more than two hundred different species of harvestable crops – eagerly taken up by several restaurants and dozens of pick-your-own subscribers – and where numerous insects and breeding birds find their home. ‘We wanted to show that it can be done; that you can combine agriculture and nature in a way that works both economically and ecologically. Actually doing something is, after all, more convincing than simply writing the idea down in a booklet.’

 Cross-pollination According to Schrama, the spirit of the project differs from that of the research in Oud Ade. ‘The big difference is that the peat meadow area is relatively manicured, whereas the food forest is a much wilder system. On top of that, Haarzuilens is situated within a nature reserve, whilst in Oud Ade we are genuinely looking for nature-inclusive models for agriculture.’ Yet there is a degree of ‘cross-pollination’ between the two projects: ‘The experiments in the polder lab run until 2031. By that time, the intention is that the cultivation systems will be mature enough to roll out elsewhere – that is absolutely achievable! We need to demonstrate in this way that scaling up to a serious commercial operation is possible, and that this type of agriculture is also profitable in the long term, without being dogmatic about it, otherwise people simply won’t believe it – and rightly so.’