Featured Research

from universities, journals, and other organizations

Organic vs. conventional farming: No clear answers from nitrogen fixing bacteria counts

Date:
February 23, 2011
Source:
American Society for Microbiology
Summary:
The population and diversity of nitrogen-fixing bacteria in agricultural soils varies more according to what crop was previously farmed than with whether those soils are organically or conventionally farmed, according to new research.

The population and diversity of nitrogen-fixing bacteria in agricultural soils varies more according to what crop was previously farmed than with whether those soils are organically or conventionally farmed, according to a paper in the February 2011 issue of the journal Applied and Environmental Microbiology.

This study was conducted as part of the ongoing and long-standing Nafferton Factorial Systems Comparison study in Northumberland in northeast England, UK. The Nafferton study has conventional and organic plots side by side, enabling precise comparisons between the two methods.

In the study, the researchers analyzed soil samples from both sets of plots, once each in March, in June, after application of fertilizer (manure to organic plots, chemical fertilizer to conventional), and in September, following application of pest control measures.

"In general, you would expect organic fertilizers and pesticides to be less harmful than conventional ones," says first author Caroline H. Orr of Northumbria University, Newcastle-upon-Tyne, UK. "However, we found that conventional fertility management led to a more active nitrogen-fixing community in June, directly after fertilizers were applied. This is possibly due to the positive effect of phosphorus, which is applied as part of conventional fertility management."

However, in September, use of organic crop protection protocols led to more activity among the nitrogen fixing bacteria as compared to when conventional pesticides were used, says Orr, suggesting that "nitrogen-fixing bacteria are particularly sensitive to the toxic effects of chemical pesticides."

It turns out the prior crop had a major influence on nitrogen-fixing activity, says Orr. Beans, legumes, commonly used in organic rotations have symbiotic relationships with bacteria that fix nitrogen for them; hence, they deplete less nitrogen from the soil, and the higher concentration of nitrate and ammonium suppresses the population of free-living nitrogen fixers. Conversely, soil growing barley (or other non-leguminous crops) would be relatively depleted of nitrogen, and so nitrogen-fixing bacteria would thrive, says Orr, remaining in higher numbers the following year.

The researchers assayed the population density of nitrogen fixing bacteria by measuring the concentration of nifH, the most conserved of the genes involved in nitrogen fixation. They sampled the density of all bacteria via 16S ribosomal RNA. The ribosomes are the machinery that reads ribonucleic acid to manufacture proteins.


Story Source:

The above story is based on materials provided by American Society for Microbiology. Note: Materials may be edited for content and length.


Journal Reference:

  1. C. H. Orr, A. James, C. Leifert, J. M. Cooper, S. P. Cummings. Diversity and Activity of Free-Living Nitrogen-Fixing Bacteria and Total Bacteria in Organic and Conventionally Managed Soils. Applied and Environmental Microbiology, 2010; 77 (3): 911 DOI: 10.1128/AEM.01250-10

Cite This Page:

American Society for Microbiology. "Organic vs. conventional farming: No clear answers from nitrogen fixing bacteria counts." ScienceDaily. ScienceDaily, 23 February 2011. <www.sciencedaily.com/releases/2011/02/110216120509.htm>.
American Society for Microbiology. (2011, February 23). Organic vs. conventional farming: No clear answers from nitrogen fixing bacteria counts. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2011/02/110216120509.htm
American Society for Microbiology. "Organic vs. conventional farming: No clear answers from nitrogen fixing bacteria counts." ScienceDaily. www.sciencedaily.com/releases/2011/02/110216120509.htm (accessed October 2, 2014).

Share This



More Plants & Animals News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Dolphins and Turtles Under Threat in Pakistan

Dolphins and Turtles Under Threat in Pakistan

AFP (Oct. 2, 2014) — The turtles and Dolphins of Pakistan's Indus river - both protected by law - are in a fight for their survival as man's activities threatens their futures. Duration: 02:29 Video provided by AFP
Powered by NewsLook.com
'Harvest Break' Endures in Maine Potato Fields

'Harvest Break' Endures in Maine Potato Fields

AP (Oct. 2, 2014) — Educators and farmers are clinging to a tradition aimed at giving farmers much-needed help in getting potatoes out of the fields and into storage before the ground freezes in the nation's northeast corner. (Oct. 2) Video provided by AP
Powered by NewsLook.com
Attacking Superbugs

Attacking Superbugs

Ivanhoe (Oct. 1, 2014) — Two weapons hospitals can use to attack superbugs. Scientists in Ireland created a new gel resistant to superbugs, and a robot that can disinfect a room in minutes. Video provided by Ivanhoe
Powered by NewsLook.com
Cultural Learning In Wild Chimps Observed For The First Time

Cultural Learning In Wild Chimps Observed For The First Time

Newsy (Oct. 1, 2014) — Cultural transmission — the passing of knowledge from one animal to another — has been caught on camera with chimps teaching other chimps. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins