For water use, our results (2.65e3.32 m3/kg rice) were much
higher than those from Wang et al. (2010) (0.431), yet compatible
with those from Blengini and Busto (2009) (4.9). However, apart
from WU, our results for Thai rice were either of similar magnitude
yet greater (energy use, GWP, ODP), or much greater (Acidification
and Eutrophication potentials) compared to the results from other
regions. This trend of LCA results per kg of rice being greater in our
case study can globally be explained by rice yields being markedly
lower in the Isaan region of Thailand aswell reflected by the sampled
systems. While yields can reach easily 4e6 tons per ha, and even
more, in the Central Plains of Thailand and in neighbouring countries,
they hardly reach 2.5 tons in Isaan, due to the specific, highquality,
high-value, low-yielding varieties of fragrant rice used
(Hom Mali). As showed previously, GWP100 per kg of rice in our case
study ranged between 2.97 and 5.55 kg CO2-eq against a range between
1.46 kg CO2-eq (Hokazono and Hayashi, 2012) and 2.374
(Blengini and Busto, 2009) from the literature. In addition to the
lower yields, the greater GWP result can be further explained by the
use of the CH4 baseline emission value suggested by Yan et al.
(2003a) that is higher than the generic one suggested by IPCC
(2006) for paddy rice, on account of specific pedoclimatic conditions
in Isaan. Our results on energy use (7.3e9.6 MJ per kg of rice)
and ODP (0.068e0.082 mg CFC11-eq per kg of rice) were similar to
those obtained by Blengini and Busto (2009) on Italian rice in highly
mechanised field conditions (8.75 MJ for non renewable energy use
and 0.06mg CFC11-eq for ODP). Conversely, our results for AP (0.04e 0.05 kg SO2-eq) and EP (0.08e0.10 kg PO4-eq) were much greater
than the values found in the literature ranging for AP from
0.00616 kg SO2-eq for Blengini and Busto (2009) to 0.024 kg SO2-eq
forWang et al. (2010) and for EP from 0.00678 kg PO4-eq for Blengini
and Busto (2009) to 0.013 kg PO4-eq for Wang et al. (2010). These
impact categories are mostly affected by field emissions of NH3, NO3
to water and P to water. As for CH4 emissions, specific emissions
factors or equationswere used to estimate field emissions in our case
study using equations from Yan et al. (2003b) for estimating
ammonia emissions and a combination of nutrient budgets (N or P)
and a precise water balance for the studied systems for N and P to
water. The greater AP and EP in our study might therefore reflect
more favourable conditions (e.g. higher temperatures) for these
emissions compared to other situations. However, the insufficient
level of detail and transparency in published LCA studies makes also
possible certain discrepancies in the methods used across studies.
Harmonised methods and assumptions would be desirable to complete
LCA study comparisons across contrasted situations