Groenekan — Which grass mixture is best suited to our dry summers? Should the plants have deep roots or shallower ones? And which type of vegetation is ultimately the best choice for a farmer? Utrecht University is seeking to investigate these and other questions this year in Groenekan.
TV segment (RTV Utrecht), photos and text by Ulrike Nagel.
Utrecht University is conducting research in Groenekan to determine which grass mixtures are most drought-resistant. On 48 marked-off plots belonging to farmer Teus Spelt, various mixtures are being monitored under different conditions using sensors that measure soil moisture, temperature, and conductivity.
The results are publicly available via a website and are expected in August. Based on this research, farmers like Spelt can make an informed choice about a suitable grass mixture for the long term.
Forty-eight plots, each 3 by 3 meters—for a total of 432 square meters—on a piece of land owned by farmer Teus Spelt in Groenekan have been divided into small plots that are being closely monitored. In the center of each plot, a white sensor protrudes from the ground, measuring, among other things, the moisture content of the soil and the air.
Edwin Pos is the scientific director of the Botanical Gardens in Utrecht and explains exactly how the experiment is set up. “We’re collecting and analyzing a lot of data here. We’re trying to understand the relationship between drought, biomass production, and ecosystem functioning. We call one of these squares a ‘plot,’ and each plot receives a different treatment. For example, we retain rainwater; some sections are covered with a roof, others aren’t; some are fertilized or mowed, while others aren’t. And we measure everything we encounter and make the data available to everyone.”
The composition of the grass mixtures also varies. “Some have low diversity and consist of only two grass species, for example, while others have very high diversity—some contain as many as sixteen herb mixtures. And we’re observing how all these different mixtures react under various conditions.”
An experiment like this is only possible because different organizations are working together. In this case, Landschap Erfgoed Utrecht is monitoring the grass plots, explains Hein Pasman. “Over the past few months, we’ve sown the grass, installed the sensors, and we’re doing this with the help of many volunteers who are working for us. Behind you are the covers—half of the plots are covered so that we can truly simulate drought conditions.”
In addition, the plots are surrounded by a layer that allows little to no moisture to pass through, explains Edwin Pos. “We have these flaps laid out here, forming a layer around the plot. Because we want as few external influences as possible—no groundwater infiltration, for example. So each test plot is lined with an EPDM layer. The sensors then measure various aspects of the test plot. The moisture content of the soil and the atmosphere above the plot, the temperature of the soil and the atmosphere—and that way we get all the information about the conditions in the plot. We then link that data to, for example, the mowing regimen and the fertilization level. This allows us to simulate both extensive and intensive land use.”
On the website www.biodiversiteitutrecht.nl, anyone can see how the individual grass plots are growing. Here, you can view the soil temperature 24 hours a day, as well as the moisture content and soil conductivity. You can click on various parameters to highlight the differences between the grass mixtures. Edwin Pos of Utrecht University: “Right now, you can’t see much of a difference there, but that makes sense because the plants haven’t grown yet. But that will change, and if you’re interested, you can follow along with us.” In addition to Utrecht University and Landschap Erfgoed Utrecht, T-Mobile, Gamma, Movares, and the Prince Bernhard Culture Fund are also involved in this project.
Who stands to benefit? Farmer Teus Spelt, for example, who has made his land available for this experiment. He used to be a dairy farmer, but he’s been raising horses on his land for 14 years now. “It’s especially important for dairy cattle to have good-quality pasture. And if it’s ruined by drought, you’re in much deeper trouble. Grass will always grow back on its own, but it’ll be of poorer quality. And then you have to start over with reseeding. And that costs a lot of money, too.”
He trusts that grass seed manufacturers know what they’re doing, “but on the other hand, they also benefit if you have to reseed your land over and over again. Because you also have to consider the environment in the long term. For the industry, I think it’s important that a lot of research be done on this. This is sandy soil, which is really sensitive to drought, so that’s why I found it interesting, too.”
Ultimately, this will allow Teus to determine which grass mixture is best suited for his soil. The researchers expect the first results in August. Edwin Pos: “All those test plots will be harvested, and then we’ll break down and analyze the data by species. That way, farmers can make an informed choice regarding both the short and long term.”
