Carbon Footprint of Commercial Vegetable Production: A Comparison of Conventional and Organic Farming in Phitsanulok Province

Abstract

The aim of this study was to assess and compare the life cycle greenhouse gas (GHG) emission of commercial vegetable production in conventional and organic production systems in Phitsanulok Province in Thailand. A cradle-to-farm-gate life cycle assessment approach was used to calculate the carbon footprint of lettuce, spring onion, and cabbage, in terms of one kg of fresh crop. Structured on farm surveys were conducted on 36 farms, which were synchronized according to cultivation schedule. The results showed that the GHG emissions from conventional farming were always higher in all the crops investigated, with the GHG emission values of the crops lettuce, spring onion, and cabbage being 0.3493, 0.2009, and 0.2757 kg CO2eq kg^-1 respectively. Organic practices lowered these values to 0.1123, 0.0753, and 0.1044 kg CO2eq kg^-1 for the corresponding crops, resulting in the total carbon footprint reduction by approximately 62-68%. The crop management stage was found to be the most carbon intensive stage of both systems in inventory disaggregation. The rather distinct emission gap was mainly caused by differences in inputs in the course of crop management; conventional systems made heavy use of synthetic N-P-K fertilizers as well as grid electricity for irrigation, which resulted in high production burdens at the beginning of the value chain and high nitrous oxide (N2O) emissions in the field. However, the organic alternative eliminated these hotspots by replacing chemical fertilizers with dried chicken manure and introducing solar-powered water pumping systems, thus reducing emissions associated with energy use. Furthermore, emission reduction from organic waste management was reduced by lower amounts of agricultural residues from the organic sector. The results enable the development of a science-based greenhouse gas emission inventory in the region and show that, by using organic amendments, low-carbon agricultural transitions can be achieved with a low carbon intensity in commercial vegetable production.