Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Adapting agricultural practices to reduce the greenhouse effect

23.11.2004


More than one-third of the greenhouse gases emitted into the atmosphere stem from agriculture and forestry. One of the current concerns is to find ways of managing agriculture differently in order to increase the level of carbon storage in soils and limit emission of gases that contribute to global atmospheric warming.



Photosynthesis ensures that plants assimilate carbon dioxide, in the form of plant carbon, part of which (in roots and crop residues) is returned to the soil and stored in a stable form in organic matter. The quantities of carbon stored in the soil depend as much on crop practices as on the soil characteristics. However, some agricultural practices (such as fertilizing and irrigation) favour emission of other greenhouse gases, such as methane and nitrous oxide. Alternative plantation management methods often recommended include the omission of ploughing and cultivation under plant cover. IRD researchers are working on quantitative field assessment of different management alternatives for agriculture and forestry in tropical areas. In Brazil, they have been working with local partners (1) and have brought to evidence the advantages of changing over from traditional methods of sugarcane harvesting involving burning to practices that omit burning.

In Brazil, sugarcane plantations occupy nearly 5 million hectares and produce 10 to 15 tonnes (dry weight) of leaves per hectare per year. Traditional harvesting is a manual method and is carried out after burning of the uncut cane. Burning of the leaves immediately changes the plant carbon into carbon dioxide and methane, which add to existing atmospheric concentrations. It also leads to emissions of nitrous oxide, which comes from part of the plant nitrogen. Methane and nitrous oxide have high potential for contributing to global warming, respectively 20 and 300 times higher than that of carbon dioxide. Moreover, plantation burning liberates potentially toxic, polluting carbon-rich ash and, owing to the elimination of leaf litter, favours soil erosion. An alternative to this system is the non-burning method, but this practice demands mechanization of harvesting (2). In this case, the leaves are left lying as a mulch on the ground. Decomposition releases most of their components (80 to 90%) as carbon dioxide into the atmosphere during the year that follows. The remainder (10 to 20%) can accumulate as litter or become incorporated in the first few centimetres of soil, in this way increasing the amount of carbon stored.


Comparative and quantitative study of these two management methods, conducted over a period of 3 to 6 years, showed that the adoption of the non-burning method induced in the first years increased storage of carbon in the soils and a reduction of total emissions of oxides of nitrogen and methane. The average quantity of litter produced in one year was estimated at 10.4 tonnes per hectare, which represents about 4.5 tonnes of carbon. Thus, in the first 20 centimetres of soil, up to 1.6 tonnes more carbon are stored during the first four years of cultivation, compared with the traditional practice using burning. Whereas few differences are observed for emissions of methane and nitrous oxide measured on the soil surface, the absence of leaf burning avoids the emission of a significant amount of these gases into the atmosphere.

Globally, carbon storage in soils and the limitation of gas emissions lead to a net annual gain of 1837 kg equivalents of stored and/or non-emitted carbon. In fact, if the whole of the surface area devoted to sugarcane in Brazil was managed using non-burning systems, the annual sequestration of carbon would represent about 15% of the emissions ascribable to the use of fossil fuels in the country.

Furthermore, this harvesting practice appears beneficial for soil fauna activity and diversity. The traditional practices in fact lead to a sharp fall in diversity and faunal biomass from levels in soil that pre-existed the start of sugarcane growing. However, just three years of the non-burning system were sufficient to restore a diversity and a faunal activity equivalent to those of the initial soil. Adoption of the non-burning system in Brazil, which has advantages for both human health and the environment, could therefore provide the country with a means of contributing to the restriction of the greenhouse effect, even of eventually joining the international market for carbon. However, this practice, which involves a change-over from manual harvesting to mechanized methods, implies substantial financial investment and a sizeable loss of jobs.

Marie Guillaume - IRD

(1) For this investigation, the IRD research unit " Séquestration du carbone dans les sols tropicaux " worked, in Brazil (Piracicaba), with the Laboratory of Environmental Biogeochemistry of the CENA (Centro de Energia Nuclear na Agricultura, University of São Paulo).

(2) In the State of São Paulo, responsible for over half of Brazil’s sugarcane output, legislation now obliges sugar refineries and distilleries to move over gradually to a non-burning harvest system. This legislation is founded on government decree n°10.547 of 2 May 2000, supplemented with decree n°11.241 of 19 September 2002.

Marie Guillaume | alfa
Further information:
http://www.ird.fr

More articles from Ecology, The Environment and Conservation:

nachricht New mathematical model can help save endangered species
14.01.2019 | University of Southern Denmark

nachricht Foxes in the city: citizen science helps researchers to study urban wildlife
14.12.2018 | Veterinärmedizinische Universität Wien

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Ten-year anniversary of the Neumayer Station III

The scientific and political community alike stress the importance of German Antarctic research

Joint Press Release from the BMBF and AWI

The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...

Im Focus: Ultra ultrasound to transform new tech

World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles

The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.

Im Focus: Flying Optical Cats for Quantum Communication

Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.

In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Our digital society in 2040

16.01.2019 | Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

 
Latest News

Scientists discover new 'architecture' in corn

21.01.2019 | Life Sciences

Broadband achromatic metalens focuses light regardless of polarization

21.01.2019 | Physics and Astronomy

Nuclear actin filaments determine T helper cell function

21.01.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>