LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

GROUP 4, SESSION B: CROP PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
116. A life cycle assessment of rice cultivation
Torsten Rehl 1, , Barbara Dannenmann 2 , Sabine Deimling 1 , Joachim Müller 2
1 PE INTERNATIONAL AG, Leinfelden-Echterdingen, Germany, 2 University of Hohenheim, Institute of
Agricultural Engineering (440), Stuttgart, Germany, Corresponding author. E-mail: t.rehl@peinternational.com
Rice cultivation represented about 22% of the world´s grain crops area in 2008 (FAO 2010). It is cultivated
across a vast area spanning wide ranges of temperate, subtropical and tropical climates. Various climatic and
socio-economic conditions at different locations effect the rice cultivation and the environmental impacts
going along with it. Rice cultivation however is a major source of green house gasses, especially methane
(CH4) (e.g. Sass 2005; Yan 2005). However, the alternation in wetting and drying to mitigate methane emissions
can increase nitrous oxide (N2O) emissions through enhanced nitrification and de-nitrification (Akiyama
2005a & b). Complex mechanisms impact not only global warming potential (GWP) but also acidification
(AP), eutrophication (EP) and photochemical ozone creation (POCP). The objective of this study was to
assess the environmental performance of different rice cultivation systems in various countries and climates.
Eight cropping systems have been chosen for data collection on precipitation, soil type, irrigation system,
fertilisation, field operations, and pesticide use: conventional, irrigated, lowland rice cultivation in China
(CC); deepwater rice cropping system in India (DWI); irrigated, conventional, lowland rice cultivation in
India with rice straw incorporation (II) and with rice straw burning (IB); irrigated, conventional, lowland rice
cultivation in the Philippines with two cropping cycles (IP2) and with three cropping cycles per year (IP3);
irrigated, organic rice cropping system in Japan (OUJ) and a rain-fed, conventional, upland rice cultivation
system in Japan (UJ). Rice systems were compared on a hectare (ha yr-1) as well as a product (kg ha-1) basis.
The life cycle assessment followed ISO 14040. The inventory quantities fossil/renewable primary energy
demand (PED) and water use (WU) were analysed. GWP, AP, EP and POCP were computed according to
the CML method (Guinée 2002).
Upland rice systems (UJ and to some degree OUJ) showed lowest impacts among the rice-cropping systems
tested in WU, GWP, AP and POCP and one of the lowest in PED and EP. OJ performed well in PED, GWP,
POCP, AP and WU. On the other hand, the highest environmental impacts was caused by the systems IP2
and IP3, due to high inputs of fertiliser, diesel etc. along with low yields. The main emissions were released
in the field by decomposition of nitrogen into NH3, NO3- and carbon into CH4. Fertiliser production and diesel
combustion in tractors and diesel generators of irrigation pumps were identified as additional sources of
emissions. A removal of straw for bio-energy or burning on the field reduces nitrogen (i.e., N2O, NOx, NO3 − )
and carbon related emissions (CH4). At the same time potential accumulation rate of soil organic carbon
decreases and consequently increase PED and GWP due to the additional demand for mineral fertiliser. The
main challenges were identified as the water regime and organic inputs, as well as the type of soil, the climate,
the field management and the production and intensity of fertiliser use.
References
Akiyama, H., Yagi, K., Yan, X., 2005. Summary of N2O emissions from rice paddy fields: Summary of
available data. Global Biogeochemical Cycle 19: 1005.
FAO (2010). FAOSTAT database, Food and Agriculture Organization (FAO). Rome
Guinée, J. B., 2002. Handbook on LCA: Operational Guide to the ISO Standards. Netherlands
Watanabe, A., Kimura, M., 1999. Influence of chemical properties of soils on methane emission from rice
paddies. Commum Soil Sci Plant Anal. 30: 2449-2463.
Yan, X., Yagi, K., Akiyama, H., Akimoto, H., 2005. Statistical analysis of the major variables controlling
methane emission from rice fields. Global Change Biology 11 (7): 1131-1141.
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