. Energy News .

Fertilizers provide mixed benefits to soil in 50-year Kansas study
by Staff Writers
Washington DC (SPX) May 01, 2013

File image.

Fertilizing with inorganic nitrogen and phosphorus definitely improves crop yields, but does it also improve the soil? The latest study to tackle this question has yielded mixed results.

While 50 years of inorganic fertilization did increase soil organic carbon stocks in a long-term experiment in western Kansas, the practice seemingly failed to enhance soil aggregate stability-a key indicator of soil structural quality that helps dictate how water moves through soil and soil's resistance to erosion.

The results of the research, which was carried out in continuous corn that was also irrigated and conventionally tilled, were somewhat surprising to lead author Humberto Blanco, a University of Nebraska-Lincoln soil physicist. The findings appear in the May-June issue of the Journal of Environmental Quality.

Fertilization typically leaves behind more crop residues in fields, he explains, which in turn can boost soil organic carbon levels. But unexpectedly in this case, "we didn't see improvement in soil aggregate stability even though soil organic carbon concentration increased," Blanco says, noting that soil particles usually bind together more strongly in aggregates as soil organic carbon concentrations rise.

He cautions, however, that more research is needed over a wider range of management and climatic conditions, particularly since studies of fertilizers' impacts on soil structural properties, such as aggregate stability, are currently few.

"Definitely the effects of inorganic fertilizer application on soil properties will depend on tillage and cropping systems," Blanco says. "So we need to look at this in other long-term experiments."

In the present study, he and co-author Alan Schlegel studied a randomized and replicated experiment that was set up in 1961 at Kansas State University's Southwest Research-Extension Center in Tribune.

The experimental plots of irrigated and tilled (disk/chisel) continuous corn have received six different rates of ammonium nitrate fertilizer (range 0 to 200 pounds/acre) for 50 years. The plots also received two rates of triple superphosphate fertilizer (0 and 18 pounds/acre) for 50 years, and a higher phosphorus rate (36 lb/acre) for 19 years.

Growing corn continuously under conventional tillage and with high inputs of water and fertilizer may seem outmoded, but this management system is "not uncommon," as demand for corn grain and crop residues grow, Blanco says.

When he tested soils from the experimental plots, he saw soil organic carbon concentrations rise gradually with increases in nitrogen fertilization at soil depths from 0 to 6 inches, although not at deeper ones. Similarly, phosphorus fertilization increased soil organic carbon at depths of 0 to 3 inches and 6 to 12 inches.

But Blanco observed a different trend in soil aggregate stability, especially when nitrogen and phosphorus were applied together at high rates.

At a depth of three to 12 inches, for example, adding more than 80 pounds of nitrogen per acre reduced the number of stable soil aggregates by 1.5 times when no phosphorus was applied, by 2.1 times at 18 pounds of phosphorus/acre, and by 2.5 times at 36 pounds of phosphorus/acre.

Blanco can't say for certain why this occurred, but he has some hypotheses. Some studies suggest that adding fertilizers rich in ammonium ions may cause soil particles to disperse rather than aggregate, thereby offsetting any positive effects of increased soil organic carbon content. Because tillage periodically disturbs the soil, it may also negate any benefits of fertilization.

Blanco is now testing these hypotheses in three additional long-term experiments in Nebraska that encompass a wider range of tillage practices and cropping systems.

The effects of nitrogen and phosphorus fertilizers on crop yields are well-researched, of course. Likewise, reduced tillage, cover crops, intensified cropping systems, and other conservation practices are known to build the soil long-term. Blanco now wants to see the two come together.

"It's clear that we need inorganic fertilizers to meet the increasing demands for food production, so it's important to look at how the extensive use of inorganic fertilizers affects soil properties in the long term," he says.

"The hypothesis is that inorganic fertilization combined with conservation tillage-strip till, no-till, and others-may improve soil structural properties relative to conventional tillage systems."


Related Links
American Society of Agronomy
Farming Today - Suppliers and Technology

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review

Newsletters :: SpaceDaily Express :: SpaceWar Express :: TerraDaily Express :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Get Our Free Newsletters
Space - Defense - Environment - Energy - Solar - Nuclear


Europe needs genetically engineered crops
London, UK (SPX) Apr 30, 2013
The European Union cannot meet its goals in agricultural policy without embracing genetically engineered crops (GMOs). That's the conclusion of scientists who write in Trends in Plant Science, a Cell Press publication, based on case studies showing that the EU is undermining its own competitiveness in the agricultural sector to its own detriment and that of its humanitarian activities in the dev ... read more

Japan's Mt Fuji to get World Heritage stamp: officials

China Successfully Sends First Gaofen Satellite Into Space

World's major development banks look closer at Earth observation

China launches high-definition earth observation satellite

Russia launches latest satellite in its global positioning system

Russia Launches New GLONASS-M Satellite

Northrop Grumman to Demonstrate Open Architecture Navigation System for DARPA

US army seeks new technology to replace GPS

Deforestation threatens Mekong region

Mekong forest facing sharp decline: WWF

Smoke signals: How burning plants tell seeds to rise from the ashes

In the Northeast, forests with entirely native flora are not the norm

Recipe for Low-Cost, Biomass-Derived Catalyst for Hydrogen Production

China conducts its first successful bio-fueled airline flight

Bugs produce diesel on demand

New input system for biogas systems

Community Solar Coming to City of Aurora and Arapahoe County

Trina Solar presents new high-efficiency products and focus on extended service proposition

How graphene and friends could harness the Sun's energy

Global Green USA Selects Far Rockaway As First 'Solar For Sandy' SiteSITE

Wind Power: TUV Rheinland Certifies HybridDrive from Winergy

UK Ministry of Defense Deems Wind Towers a National Security Threat

Wales wind power line to go underground near historic village

U.S. leads in wind installations

Australia in danger of 'carbon bubble'

Greenpeace activists board coal ship off Australia reef

Outside View: Coal exports save lives

China mine blast kills 28: state media

China officials holding secret sauna parties: state media

Cancer victim with jailed family faces China land battle

China hands down death sentences in lending crackdown

China investigating clashes that killed 21

The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement