Carbon footprint of rubber/sugarcane intercropping system in Sri Lanka: a case study

Abstract

The global climate has been changing with the elevated CO2 in the atmosphere; hence identification of effective measures to mitigate or combat the adverse effects of climate change is at uttermost importance. The goal of Government of Sri Lanka (GoSL) for planting 40,000 ha of rubber (Hevea brasiliensis Muell. Arg.) in the Uva province may partly address this issue sequestering the key greenhouse gas (GHG), CO2. Farmers in the area usually practice intercropping sugarcane (Saccharum officinarum) under immature rubber plants for extra income during the initial period of rubber cultivation. In the process of valuing rubber cultivation in mitigating the climate change effect, information on net greenhouse gas (GHG) emission from rubber/sugarcane intercropping system is required. Being scanty of such knowledge, this study was aimed to estimate the carbon footprint in the cultivation of rubber/sugarcane intercropping system in Sri Lanka.GHG emissions from the cultivation of rubber and sugarcane were calculated using the information available in the smallholdings having rubber/sugarcane intercropping in Monaragala district (IL2). GHG emission resulting from raw rubber processing, i.e. Ribbed Smoked Sheets (RSS) and Crepe Rubber (CR), was assessed using the data available in Kumarawatta Estate, Monaragala and Dartonfield Estate, Agalawatta, respectively. Also, GHG emission resulting from processing refined sugar was gathered from Palwatta Sugar Industries (Ltd), Monaragala. Carbon sequestration capacities of both crops were adopted from previous studies. Guidelines of Intergovernmental Panel on Climate Change (IPCC) were used in the estimation of carbon footprint. GHG emission in the process of cultivating rubber for its lifespan (30 years) was 65.15 CO2-eq ton/ha. When sugarcane was cultivated in rubber lands for four year period as a rubber/sugarcane intercropping system, GHG emission increased only by 9.72 CO2-eq ton/ha. Processing of RSS throughout the lifespan was responsible for additional 93.49 CO2-eq ton/ha emission whilst that for processing CR was limited to 50.14 CO2-eq ton/ha. Processing of refined sugar during four year intercropping period was accountable only for 0.62 CO2-eq ton/ha emission. In conclusion, carbon footprint (Net GHG emission) of cultivating rubber/sugarcane intercrop to produce CR and refined sugar was -1537.02 CO2-eq ton/ha/30yr whilst that for RSS and refined sugar was -1493.73 CO2-eq ton/ha/30yr. Increase in carbon footprint by intercropping sugarcane was only ca. 0.5% over mono cropping rubber. Potential application of this information in developing carbon trading projects is discussed.