As atmospheric CO2 levels rise, methods to mitigate these increases are becoming very important. Three studies published in the July-August 2008 issue of Soil Science Society of America Journal explore the potential roles of soils as a C sink in different regions in the Western Hemisphere.
Scientists from Alberta Agriculture and Rural Development (Canada), the National Institute of Agricultural Technology, the University of Buenos Aires (Argentina), and University of California, Davis (USA) have investigated soil C balance in distinct agroecosystems under different management practices including soil tillage, N fertilization, elimination of fallow, and establishment of grass. In each case, C sequestration occurred in response to higher C input to soil; however, increase in SOC was confined to labile fractions such as the light fraction and larger soil aggregates.
In southeastern Alberta, a long-term study showed previously that eliminating summer fallow or establishing grass significantly increased soil organic C after 6 yr. In the 12th year of the study, total organic C and light fraction C were determined in three rotations with summer fallow, two continuously cropped rotations and grass. All rotations had subtreatments with different levels of fertilization. The light fraction of soil C was obtained using density separation and consisted mostly of non-decomposed root and straw fragments.
Although soil organic C was increased by elimination of summer fallow, fertilization, and establishment of grass, gains in soil organic C between Years 6 and 12 were negligible in all treatments except the fertilized grass treatment. Most of the gains in total soil organic C were due to increased light fraction C. The results indicate that much of the gain in soil organic C in response to improved practices on semiarid prairie soils likely occurs within one decade.
The full article is available for no charge for 30 days following the date of this summary. View the abstract at: http://soil.scijournals.org/cgi/content/abstract/72/4/970
In the semiarid portion of the Pampas, scientist compared no-till management to a conventional tillage system (disk-tillage). Emissions of CO2-C from the soil and crop C inputs were determined, estimating soil C balance under both tillage systems.
As a part of this study, a field experiment was performed during 6 yr on an Entic Haplustoll where no-till and disk-tillage was applied to a soil cropped under a common rotation in the region (oat + hairy vetch, corn, wheat, oat). From Year 3 to 6 in situ CO2-C fluxes were measured and C inputs from above and below ground plant residues were estimated.
Results showed that in the semiarid environment of the study C sequestration occurred under no-till. The sequestration process was attributed to the effect of tillage systems on crop productivity rather than on the mineralization intensity of soil organic pools.
The full article is available for no charge for 30 days following the date of this summary. View the abstract at: http://soil.scijournals.org/cgi/content/abstract/72/4/1140
Investigation: United States
In Kentucky (USA) a study was conducted in a corn agroecosystem experiment to test the soil C saturation concept which postulates that there is an upper limit to the equilibrium soil C level of mineral soils even when soil C input is increased. In this experiment, a gradient of soil C input was produced with four N fertilizer application rates under two tillage systems, no-till and moldboard plowing. To investigate if physical protection of organic C leads to soil C saturation, C stabilization in soil fractions that differ in C stabilization potential was determined, and the relationship between soil C input and soil organic C was analyzed.
Total soil organic C was positively related to C input, and this was primarily due to C stabilization in larger soil aggregates. In both tillage systems, however, C in the two smallest soil size fractions did not increase with greater C input. Moreover, in three soil fractions further separated from larger soil aggregates, C associated with particulate organic matter and microaggregates increased with C input, but there was no increase in C associated with silt-plus-clay, which was the smallest soil size fraction.
Haegeun Chung at University of California, Davis, the first author of the study conducted in Kentucky (USA), stated “Our results indicate that soil fractions with low C stabilization potential show C saturation. Therefore, we need to consider soil C saturation levels to better predict the change in C sink capacity and fertility of soils when soil C input increases under higher plant production or organic amendment.”
The full article is available for no charge for 30 days following the date of this summary. View the abstract at http://soil.scijournals.org/cgi/content/abstract/72/4/1132.
Soil Science Society of America Journal, http://soil.scijournals.org, is a peer-reviewed international journal published six times a year by the Soil Science Society of America. Its contents focus on research relating to physics; chemistry; biology and biochemistry; fertility and plant nutrition; genesis, morphology, and classification; water management and conservation; forest, range, and wildland soils; nutrient management and soil and plant analysis; mineralogy; and wetland soils.
The Soil Science Society of America (SSSA) is a progressive, international scientific society that fosters the transfer of knowledge and practices to sustain global soils. Based in Madison, WI, and founded in 1936, SSSA is the professional home for 6,000+ members dedicated to advancing the field of soil science. It provides information about soils in relation to crop production, environmental quality, ecosystem sustainability, bioremediation, waste management, recycling, and wise land use.
SSSA supports its members by providing quality research-based publications, educational programs, certifications, and science policy initiatives via a Washington, DC, office. For more information, visit www.soils.org.
SSSA is the founding sponsor of an approximately 5,000-square foot exhibition, Dig It! The Secrets of Soil, opening July 19, 2008 at the Smithsonian's National Museum of Natural History in Washington, DC.
Sara Uttech | Newswise Science News
Some brain tumors may respond to immunotherapy, new study suggests
11.12.2018 | Columbia University Irving Medical Center
Climate change and air pollution damaging health and causing millions of premature deaths
30.11.2018 | International Institute for Applied Systems Analysis (IIASA)
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
14.12.2018 | Power and Electrical Engineering
14.12.2018 | Physics and Astronomy
14.12.2018 | Physics and Astronomy