A Comparative Study on Energy Use and Greenhouse Gas Emissions in Conventional and Organic Agriculture

Abstract

Abstracts

A Comparative Study on Energy Use and Greenhouse Gas Emissions in Conventional and Organic Agriculture

Kisong Lee Regional Information Department of Agricultural Economics and Rural Development Graduate School Seoul National University

How to enhance the efficiency of energy use and to abate greenhouse gas emissions (GHGE) in agriculture has become very decisive in the mitigation of climate change. Organic farming has been recognized as the most reasonable alternative in agriculture to overcome this climate crisis. Studies on comparisons of energy use and greenhouse gas emissions (GHGE) between conventional and organic farming have been carried out vigorously in the previous decades. However, controversies exist over the problems in comparative studies on energy use and greenhouse gas emissions. Taking these contexts into consideration, the objectives of this study are (i) to identify the structural variables to determine the differences of energy efficiency (EE) and greenhouse gas emissions (GHGE) between conventional and organic farming systems through meta-analysis of previous studies

(ii) to examine which input categories and farming practices cause the differences of energy efficiency (EE) and greenhouse gas emissions (GHGE) between conventional farming systems (CFS) and organic farming systems (OFS) by applying field studies on soybean production in Korea

and thereby, (iii) to explore alternative solutions to decrease environmental impacts in agriculture. First, the results of meta-analysis can be summarized as follows. 1. The results of the analysis obtained from 165 observations of 68 previous studies on the use of energy illustrate that 67.3% of their observations is positive in the organic superiority of EE - which means organic EE is higher than its counterpart. 2. In comparisons of EE ratio (%), - organic EE versus conventional EE -, the total mean value of EE ratio is 128.5%. This concludes that the EE of organic farming averages approximately 30% higher than that of conventional farming. 3. The results of the analysis on 195 observations of 66 previous studies on GHGE demonstrate that 67.7% of their observation is positive in the organic superiority of GHGE - which means organic GHGE is lower than its counterpart. The organic superiority of GHGE per ha basis is positive by 71.4%, and per ton basis is positive by 60.3%. 4. The GHGE ratio(%) shows 88.2%, which means that GHGE of organic farming is around 12% lower on the average than that of conventional farming. The GHGE ratio average per ha basis is 69.2%, which indicates that the GHGE of organic farming system (OFS) is considerably lower than that of conventional farming system (CFS), and the GHGE per ton basis is 96.5% on the average, which indicates that there is no difference between both systems per ton product unit. 5. As for the structural variables to determine the organic superiority of EE and GHGE, the duration of the data collection is estimated as the significantly influential variable to drive organic superiority of EE. The researchers selection on the energy coefficient values of input materials also appears as a very significant factor to affect the difference of EE between conventional farming systems (CFS) and organic farming systems (OFS). On the other hand, the variables of sample size, unit class, and farm product types appear to have a positive relationship with the organic superiority of GHGE. Second, the results of the field study on soybean production systems in Korea show considerable disparities with the European and American experiences. 1. The EE (0.98) of organic soybean farms is noticeably poorer than that of conventional farms (1.56). The energy consumption of OFS is higher than that of CFS, since the yields of OFS are apparently lower than that of CFS. 2. Seeds and mulch film in OFS and pesticides in CFS cause significant differences between both systems. Mulching and seeding used in OFS as well as weeding and spraying in CFS show significant variations between both systems. 3. Analysis of the input variables to drive the EE shows that fuel, fertilizers, mulch film, and labor are the influential input variables. As for the variables regarding farming practices to determine the EE, cultivation, mulching, threshing and grading are significantly related with EE. 4. The GHGE of organic soybean farms (1562.3 kg CO2eq/ha) is relatively lower than that of conventional farms (2003.2 kg CO2eq/ha). However, with respect to the product unit basis, the GHGE of organic soybean farms (1629.8kg CO2eq/ton) is inversely just a little higher than that of conventional farms (1473.1 kg CO2eq/ton). 5. In comparison of the GHGE by input categories between CFS and OFS, seeds and mulch film in OFS and pesticides in CFS led to significant differences between both systems. 6. Analysis of the input variables to drive the outcome of GHGE in both farm systems indicates fertilizers as a variable which is strongly influential. 7. Comparisons of LCIA (Life Cycle Impacts Assessment) between both soybean production systems show that 9 categories except ARD, EP and EU among 12 environmental impacts appear higher in CFS than in OFS. 8. In soybean production in Korea, fertilizers and manure are responsible for 37% of the total energy consumption in both systems. And they are the absolute contributors to GHGE which amount to 67.8% of total GHGE in both systems. This result indicates that although the use of synthetic fertilizers is reduced, the heavy use of animal manure can contribute greatly to the emission of nitrous oxide, which leads to the increase of GHGE. The substitution of manure in the place of synthetic fertilizers banned under organic agriculture regulations is not a recommendable alternative for organic farming. Therefore, reasonable strategies to mitigate climate change through energy consumption and GHGE reduction should be conducted not within, but beyond the scope of the nitrogen cycle. Finally, most previous studies did not present detailed statistical data except for the descriptive statistics of performance variables. This has led to limitation in explaining definitely the relationship of performance variables and structural variables. Therefore, for the progress of future EE and GHGE studies, presentation of more detailed data through the appropriate statistical analyses is required. In addition, more researches are needed in Asian countries including Korea, where studies on energy use and GHGE have not been pursued actively to date.

Key Words : Energy use, Energy efficiency , Greenhouse gas emissions, Organic farming, Global warming. Climate change. Meta-analysis

Student ID

85514-806 E-mail : lgeesong@gmail.com