Nav: Home

How does an increase in nitrogen application affect grasslands?

May 19, 2020

Virtually all of the grasslands in Europe are managed by farmers and whilst traditional management involved periodic cutting and grazing, modern intensive management involves applications of large amounts of nitrogen fertiliser to increase grass production. Traditionally managed grasslands contained many plant species, but intensively managed ones contain only a few fast-growing ones that profit from the high nutrient levels. The number of disease-causing plant pathogens also increases with fertilisation. All of these changes are occurring simultaneously; however, ecologists do not know which are most important or what happens when several change at the same time.

The PaNDiv (Pathogens, Nitrogen and Diversity) experiment of the Institute of Plant Sciences at the University of Bern is unique because it manipulates many of these factors to see how they interact with each other. In their first article, "Decomposition disentangled" the authors focussed on litter decomposition, i.e. the speed at which plant matter rots down, which is critical for maintaining a healthy and fertile soil.

More than 800 nylon bags

"Nitrogen shifted the plant community towards more fast-growing plant species and this in turn made the leaves decompose faster (feeding back more nitrogen to the soil). This indicates that fertilisation effects on functioning are underestimated if we don't consider the changes in species composition", explains Dr. Noémie Pichon, first author of the study. Litter from fast growing plants decomposes faster because fast growing species invest less in structural tissue and build thinner larger leaves with higher nitrogen content, which are efficient at capturing light but which don't live long. These leaves rot down faster than the small thick leaves produced by slow growing plants. Small nylon bags were filled with litter and left to decompose on each plot to test how fast the biomass produced breaks down. "We ended up sewing more than 800 bags with a sewing machine, but the quality of the results was worth the amount of work" continues Dr. Pichon.

Testing different factors at the same time

Eric Allan, project leader and professor at the Institute of Plant Sciences, says: "The results of our first study show why this kind of experiment is needed: understanding ecosystem functioning is complicated and only by testing many different factors at the same time can we understand their importance and therefore predict how our ecosystems will change in the future".

Several experiments have shown that ecosystems with more plant species have higher levels of ecosystem functioning. However, the PaNDiv experiment is unique because it not only manipulates plant diversity, on small plots of 2 x 2m, but also varies the type of plant species present. This is done by creating plant communities consisting of only fast-growing plants (which thrive in fertile soil) or only slow growing plants (that prosper in poorer conditions). It also combines these treatments with nitrogen fertilisation and the application of fungicide to remove plant pathogens. On each plot, the researchers measured several ecosystem functions. These included: how much plant matter they produced; how active the soil organisms were; the levels of nutrients and carbon in the soil; as well as the number of insects and plant pathogens present. The PaNDiv experiment is located in the small Swiss town of Münchenbuchsee, near the capital Bern. Pichon et al. 2020 is the first article of a long series that will be published using PaNDiv results.
-end-


University of Bern

Related Nitrogen Articles:

Reducing nitrogen with boron and beer
The industrial conversion of nitrogen to ammonium provides fertiliser for agriculture.
New nitrogen products are in the air
A nifty move with nitrogen has brought the world one step closer to creating a range of useful products -- from dyes to pharmaceuticals -- out of thin air.
'Black nitrogen'
In the periodic table of elements there is one golden rule for carbon, oxygen, and other light elements.
A deep dive into better understanding nitrogen impacts
This special issue presents a selection of 13 papers that advance our understanding of cascading consequences of reactive nitrogen species along their emission, transport, deposition, and the impacts in the atmosphere.
How does an increase in nitrogen application affect grasslands?
The 'PaNDiv' experiment, established by researchers of the University of Bern on a 3000 m2 field site, is the largest biodiversity-ecosystem functioning experiment in Switzerland and aims to better understand how increases in nitrogen affect grasslands.
Reducing reliance on nitrogen fertilizers with biological nitrogen fixation
Crop yields have increased substantially over the past decades, occurring alongside the increasing use of nitrogen fertilizer.
Flushing nitrogen from seawater-based toilets
With about half the world's population living close to the coast, using seawater to flush toilets could be possible with a salt-tolerant bacterium.
We must wake up to devastating impact of nitrogen, say scientists
More than 150 top international scientists are calling on the world to take urgent action on nitrogen pollution, to tackle the widespread harm it is causing to humans, wildlife and the planet.
How nitrogen-fixing bacteria sense iron
New research reveals how nitrogen-fixing bacteria sense iron - an essential but deadly micronutrient.
Corals take control of nitrogen recycling
Corals use sugar from their symbiotic algal partners to control them by recycling nitrogen from their own ammonium waste.
More Nitrogen News and Nitrogen Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.