Navigation Links
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.


Contact: Sandra Hines
University of Washington

Related biology news :

1. New system to restore wetlands could reduce massive floods, aid crops
2. Reproductive health providers should discuss environmental exposure risks with patients
3. Research on flavanols and procyanidins provides new insights into how these phytonutrients may positively impact human health
4. Artificial wetlands can provide benefits over the long haul
5. Discovery provides blueprint for new drugs that can inhibit hepatitis C virus
6. Heightened Security Threats and Economic Issues Provide Fillip to Global Civil and Military Biometrics Market, Says Frost & Sullivan
7. Bowman provides strategies to engage public with climate change solutions
8. Scientists provide first large-scale estimate of reef shark losses in the Pacific Ocean
9. Fruit flies provide new knowledge about uninhibited cell growth
10. Key proteins newly discovered form and function may provide novel cancer treatment target
11. Michael J. Fox Foundation grant to Dr. Samuel Young will provide Parkinsons drug development tools
Post Your Comments:
Related Image:
Floods didn't provide nitrogen 'fix' for earliest crops in frigid North
(Date:10/29/2015)...  Connected health pioneer, Joseph C. Kvedar , ... health and wellness, and the business opportunities that arise ... Internet of Healthy Things . Long before health ... Dr. Kvedar, vice president, Connected Health, Partners HealthCare, was ... care from the hospital or doctor,s office into the ...
(Date:10/27/2015)... 2015 Synaptics Inc. (NASDAQ: SYNA ), the ... has adopted the Synaptics ® ClearPad ® ... its newest flagship smartphones, the Nexus 5X by LG ... --> --> Synaptics works closely ... collaboration in the joint development of next generation technologies. ...
(Date:10/23/2015)... GOLETA, California , October 23, 2015 /PRNewswire/ ... SensoMotoric Instruments (SMI) announce a mobile plug and play ... during interactive real-world tasks SensoMotoric Instruments (SMI) ... their established wearable solutions for eye tracking and physiological ... captured with SMI Eye Tracking Glasses 2w ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... 2015 2 nouvelles études permettent d ... les différences entre les souches bactériennes retrouvées dans la plaque ... êtres humains . Ces recherches  ouvrent une nouvelle ... en charge efficace de l,un des problèmes de ... .    --> 2 nouvelles études permettent ...
(Date:11/25/2015)... IN (PRWEB) , ... November 25, 2015 , ... ... (AMA) and the Organization of Black Aerospace Professionals (OPBAP) has been formalized with ... and other AMA team leaders met with OPBAP leaders Capt. Karl Minter and ...
(Date:11/24/2015)... ... 2015 , ... The United States Golf Association (USGA) today announced Dr. Bruce ... Presented annually since 1961, the USGA Green Section Award recognizes an individual’s distinguished service ... , Clarke, of Iselin, N.J., is an extension specialist of turfgrass pathology in the ...
(Date:11/24/2015)... ... November 24, 2015 , ... ... year and one of the premier annual events for pharmaceutical manufacturing: 2015 Annual ... November 2015, where ISPE hosted the largest number of attendees in more than ...
Breaking Biology Technology: