Fertilizer could be too much of a good thing for the world's grasslands, according to study findings to be published online Feb. 16 by the journal Nature.
This map shows Nutrient Network sites studied. Numbers correspond to chart included with Nature article describing each site.
The worldwide study shows that, on average, additional nitrogen will increase the amount of grass that can be grown. But a smaller number of species thrive, crowding out others that are better adapted to survive in harsher times. It results in wilder swings in the amount of available forage.
"More nitrogen means more production, but it's less stable," said Johannes M.H. Knops, a University of Nebraska-Lincoln biologist and one of the paper's international co-authors. "There are more good years and more bad years. Not all years are going to be good and the bad years are going to be worse."
The three-year study monitored real-world grasslands at 41 locations on five continents. The sites included alpine grasslands in China, tallgrass prairies in the United States, pasture in Switzerland, savanna in Tanzania and old fields in Germany. Two sites in Nebraska were part of the study, the Cedar Point Biological Station near Ogallala and the Barta Brothers Ranch in the Sandhills near Valentine.
The study found common trends among grasslands around the world:
•Natural -- unfertilized -- grasslands with a variety of grass species have more stability because of species "asynchrony," which means that different species thrive at different times so that the grassland produces more consistently over time. This finding was consistent with the findings of previous, single-site studies as well as previous biodiversity experiments conducted in Europe.
•Fertilized plots saw declines in the numbers of species compared to unfertilized control plots. The plots averaged from 4.4 species to 32.3 species per square meter and declined by an average of 1.3 species per site.
•Fertilization reduced species asynchrony and increased the variation in production levels over time compared to control plots. This weakened the benefits of species diversity seen in the un-manipulated plots.
While public attention has grown about elevated levels of carbon dioxide and global warming, Knops said elevated levels of mineral nitrogen in the environment also are concerning. While it's rare for ranchers and farmers to fertilize rangeland and pasture, grasslands are affected by nitrogen deposition that results from burning fossil fuels, as well as from fertilizer runoff and ammonia volatilization from cropland.
Knops said fertilizer overuse could intensify the detrimental effects of drought on grasslands, such as the drought that devastated cattle herds in Texas and Oklahoma from 2011-13, when Texas lost about 15 percent of its cattle herd, or about 2 million animals.
It also could have ripple effects during bad years by reducing the plant cover, which increases erosion, and decreases water filtration and carbon sequestration benefits provided by grasslands.
The Nature article, "Eutrophication weakens stabilizing effects of diversity in natural grasslands," is one of several research articles on the relationships between grassland diversity, productivity and stability, generated by the Nutrient Network experiment. Knops called it an unprecedented experiment.
"In the past you didn't see a collaborative effort at a really large scale like this in biology or in ecology," he said.
For more information about the Nutrient Network effort, visit http://www.nutnet.org
Alkaline soil, sensible sensor
03.08.2017 | American Society of Agronomy
New 3-D model predicts best planting practices for farmers
26.06.2017 | Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences