Abstract:
Paddy cultivation is well established in nine out of 15 agro ecological regions of the wet
zone of Sri Lanka. Kalutara District plays a major role in paddy cultivation and farmers
predominantly follow conventional methods in paddy cultivation. However, there is an
emerging trend to adopt organic farming due to better prices for rice of traditional varieties
grown without chemical inputs. The goal of this study was to compare cost of environmental
impacts of paddy cultivation practiced under conventional and organic methods. The study
used life cycle assessment (LCA) as a tool and eco-costing method. The study was
conducted using input output data from 156 farmers for the 2014 Yala season. The
functional unit used in the study was 100 kg of paddy at the farm gate. First, all emissions
and the consumption of resources connected to different processes were listed in a Life
Cycle Inventory (LCI). Six indicators for environment impacts; global warming;
eutrophication; human toxicity; terrestrial eco-toxicity; freshwater aquatic toxicity; depletion
of abiotic resources and atmospheric acidification were considered. These impacts were
then converted to monetary values adopting the eco-costing method to compare the
environmental damage cost of the two systems.
The results indicate that the value of global warming potential of inorganic cultivation is 717
Rs/kg CO2 eq followed by 323 Rs/ kg SO2 eq of acidification, and 1105 Rs/kg PO4
3- eq of
eutrophication. Values for organic paddy cultivation for the above indicators are
respectively, 181 Rs/kg CO2 eq, Rs/kg SO2 eq, and 260 Rs/kg PO4
3-. The total damage cost
of human, freshwater, and eco toxicity from conventional cultivation is 3,334,093 Rs/kg
DBeq. The total damage cost of organic cultivation is only Rs.770 which is only a minute
fraction when compared to the total damage cost of Rs.30,146,801 in conventional
cultivation. The study demonstrates that the eco-cost method is an appropriate tool in
determining the environmental cost between comparable production systems by
incorporating the LCA tool. It further reveals that the adoption of an organic system is
environmentally more profitable than the conventional cultivation of rice.
