PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Floods didn't provide nitrogen 'fix' for earliest crops in frigid North

2013-11-07
(Press-News.org) Contact information: Sandra Hines
shines@uw.edu
206-543-2580
University of Washington
Floods didn't provide nitrogen 'fix' for earliest crops in frigid North

Floods didn't make floodplains fertile during the dawn of human agriculture in the Earth's far north because the waters were virtually devoid of nitrogen, unlike other areas of the globe scientists have studied.

Instead, the hardy Norsemen and early inhabitants of Russia and Canada have microorganisms called cyanobacteria to mostly thank for abundant grasses that attracted game to hunt and then provided fodder once cattle were domesticated. The process is still underway in the region's pristine floodplains.

The new findings are surprising because it's long been assumed that nitrogen crucial to plant growth mainly arrived with floods of river water each spring, according to Thomas DeLuca, a University of Washington professor of environmental and forest sciences and lead author of a paper in the Nov. 6, 2013 issue of the journal PLOS ONE.

Discovering that cyanobacteria in the floodplains were responsible for nitrogen fixation – that is taking it from the atmosphere and "fixing" it into a form plants can use – partially resolves the scientific debate of how humans harvested grasses there for hundreds of years without fertilizing, DeLuca said. It raises the question of whether farmers today might reduce fertilizer use by taking advantage of cyanobacteria that occur, not just in the floodplains studied, but in soils around the world, he said.

It also might lead to more accurate models of nitrogen in river systems because none of the prominent models consider nitrogen being fixed in floodplains, DeLuca said. Scientists model nitrogen loading of rivers, especially where industrial fertilizers and effluent from wastewater-treatment plants cause dead zones and other problems in the lower reaches and mouths of rivers.

Ten rivers and 71 flood plains were studied in northern Fennoscandia, a region that includes parts of Scandinavia and Finland. The rivers were chosen because their upper reaches are pristine, haven't been dammed and are not subject to sources of human-caused nitrogen enrichment – much like river systems humans encountered there hundreds of years ago, as agriculture emerged in such "boreal" habitats. Boreal habitat – found at 60 degrees latitude and north all the way into the Arctic Circle, where it meets tundra habitat – is the second largest biome or habitat type on Earth.

In the northern regions of the boreal, the surrounding hillsides have thin, infertile soils and lack shrubs or herbs that can fix nitrogen. In these uplands, feather mosses create a microhabitat for cyanobacteria, which fix a modest amount of nitrogen that mostly stays on site in soils, trees and shrubs. Little of it reaches waterways. On the floodplains, high rates of nitrogen fixation occur in thick slimy black mats of cyanobacteria growing in seasonably submerged sediments and coating the exposed roots and stems of willows and sedges.

"We joke and call the floodplains the 'mangroves of the North' because there are almost impenetrable tangles of willow tree roots in places, like a micro version of the tropical and subtropical mangroves that are known to harbor highly active colonies of cyanobacteria," DeLuca said.

"It turns out there's a lot of nitrogen fixation going on in both," he said. For example, the scientists discovered that in spite of the dark, cold, snowy winters of Northern Sweden, the cyanobacteria there fix nitrogen at rates similar to those living the life in the toasty, sun-warmed Florida Everglades.

The amount of nitrogen provided by the cyanobacteria to unharvested willows and sedges is perhaps a quarter of what U.S. farmers in the Midwest apply in industrial fertilizers to grain crops and as little as a sixth of what they apply to corn.

Human-made fertilizers can be fuel-intensive to produce and use, for example, it takes the energy of about a gallon of diesel to produce 4 pounds of nitrogen fertilizer. In developing countries in particular, nitrogen fertilization rates are spiraling upward, driving up fossil-fuel consumption, DeLuca said. Meanwhile, cyanobacteria naturally occurring in farm soils aren't fixing nitrogen at all in the presence of all that fertilizer, they just don't expend the energy when nitrogen is so readily available, he said.

"Although modest in comparison to modern fertilization, the observation that cyanobacteria could drive the productivity of these boreal floodplain systems so effectively for so long makes one question whether cyanobacteria could be used to maintain the productivity of agricultural systems, without large synthetic nitrogen fertilizer inputs," he said.



INFORMATION:

Co-authors on the paper are Olle Zackrisson and Ingela Bergman with the Institute for Subarctic Landscape Research, Sweden, Beatriz Díez with Pontificia Universidad Católica, Chile, and Birgitta Bergman with Stockholm University.

Funding for the work came from the European Regional Development Fund and the Bank of Sweden Tercentenary Foundation.

For more information: DeLuca, 206-685-1928, deluca@uw.edu

Suggested websites: DeLuca UW School of Environmental and Forest Sciences PLOS ONE Olle Zackrisson and Ingela Bergman Beatriz Díez Birgitta Bergman



ELSE PRESS RELEASES FROM THIS DATE:

Monkeys use minds to move 2 virtual arms

2013-11-07
Monkeys use minds to move 2 virtual arms DURHAM, N.C. – In a study led by Duke researchers, monkeys have learned to control the movement of both arms on an avatar using just their brain activity. The findings, published Nov. 6, 2013, in the ...

X-rays reveal inner structure of the Earth's ancient magma ocean

2013-11-07
X-rays reveal inner structure of the Earth's ancient magma ocean First look into molten basalt at deep mantle conditions This news release is available in German. Using the world's most brilliant X-ray source, scientists have for the first ...

Stress makes snails forgetful

2013-11-07
Stress makes snails forgetful Snail study reveals that stress is bad for memory New research on pond snails has revealed that high levels of stress can block memory processes. Researchers from the University of Exeter and the University of Calgary trained snails ...

Annual car crash deaths in England and Wales have fallen 40 percent in 50 years

2013-11-07
Annual car crash deaths in England and Wales have fallen 40 percent in 50 years But may still contribute to social class and gender differences in life expectancy The annual number of car crash deaths in England and Wales has plunged by 41% over the past ...

Crime associated with higher mortality rates

2013-11-07
Crime associated with higher mortality rates The new study, published in the journal PLOS ONE shows that people with drug-related criminal records in Norway have a mortality rate that can be up to 15 times higher than people ...

Discovery of HIV 'invisibility cloak' reveals new treatment opportunities

2013-11-07
Discovery of HIV 'invisibility cloak' reveals new treatment opportunities Scientists have discovered a molecular invisibility cloak that enables HIV, the virus that causes AIDS, to hide inside cells of the body without triggering the body's natural defence systems. ...

Study uncovers new explanation for infection susceptibility in newborns

2013-11-07
Study uncovers new explanation for infection susceptibility in newborns CINCINNATI – Cells that allow helpful bacteria to safely colonize the intestines of newborn infants also suppress their immune systems to make them more vulnerable ...

Newly discovered predatory dinosaur 'king of gore' reveals the origins of T. rex

2013-11-07
Newly discovered predatory dinosaur 'king of gore' reveals the origins of T. rex November 6, 2013, Salt Lake City, UT – A remarkable new species of tyrannosaur has been unearthed in Grand Staircase-Escalante National Monument (GSENM), southern Utah. The huge ...

New study identifies signs of autism in the first months of life

2013-11-07
New study identifies signs of autism in the first months of life Scientists at Marcus Autism Center, Children's Healthcare of Atlanta and Emory University School of Medicine identify markers of social disability present in 2 to 6-month-old infants later diagnosed ...

RNA controls splicing during gene expression, further evidence of 'RNA world' origin in modern life

2013-11-07
RNA controls splicing during gene expression, further evidence of 'RNA world' origin in modern life RNA is the key functional component of spliceosomes, molecular machines that control how genes are expressed, report scientists from the University ...

LAST 30 PRESS RELEASES:

Breathable yet protective: Next-gen medical textiles with micro/nano networks

Frequency-engineered MXene supercapacitors enable efficient pulse charging in TENG–SC hybrid systems

Developed an AI-based classification system for facial pigmented lesions

Achieving 20% efficiency in halogen-free organic solar cells via isomeric additive-mediated sequential processing

New book Terraglossia reclaims language, Country and culture

The most effective diabetes drugs don't reach enough patients yet

Breast cancer risk in younger women may be influenced by hormone therapy

Strategies for staying smoke-free after rehab

Commentary questions the potential benefit of levothyroxine treatment of mild hypothyroidism during pregnancy

Study projects over 14 million preventable deaths by 2030 if USAID defunding continues

New study reveals 33% gap in transplant access for UK’s poorest children

Dysregulated epigenetic memory in early embryos offers new clues to the inheritance of polycystic ovary syndrome (PCOS)

IVF and IUI pregnancy rates remain stable across Europe, despite an increasing uptake of single embryo transfer

It takes a village: Chimpanzee babies do better when their moms have social connections

From lab to market: how renewable polymers could transform medicine

Striking increase in obesity observed among youth between 2011 and 2023

No evidence that medications trigger microscopic colitis in older adults

NYUAD researchers find link between brain growth and mental health disorders

Aging-related inflammation is not universal across human populations, new study finds

University of Oregon to create national children’s mental health center with $11 million federal grant

Rare achievement: UTA undergrad publishes research

Fact or fiction? The ADHD info dilemma

Genetic ancestry linked to risk of severe dengue

Genomes reveal the Norwegian lemming as one of the youngest mammal species

Early birds get the burn: Monash study finds early bedtimes associated with more physical activity

Groundbreaking analysis provides day-by-day insight into prehistoric plankton’s capacity for change

Southern Ocean saltier, hotter and losing ice fast as decades-long trend unexpectedly reverses

Human fishing reshaped Caribbean reef food webs, 7000-year old exposed fossilized reefs reveal

Killer whales, kind gestures: Orcas offer food to humans in the wild

Hurricane ecology research reveals critical vulnerabilities of coastal ecosystems

[Press-News.org] Floods didn't provide nitrogen 'fix' for earliest crops in frigid North