Greenhouse gas emissions from agricultural land use in the coastal area of Red River Delta

Abstract

This study aims to provide reliable greenhouse gas emission data from dominant land-use types in the coastal areas of the Red river delta, Vietnam. The field measurements were conducted on freshwater paddy rice, paddy rice with salinity intrusion, rice–vegetable rotation, and continuous vegetables for two consecutive years. Greenhouse gases were measured for methane, carbon dioxide, and nitrous oxide. The results showed that annual CH4 emissions were highest in the paddy rice with salinity intrusion (1852 kg C ha−1), followed by freshwater rice paddy (971 kg C ha−1), rice–vegetable rotation (102 kg C ha−1), and continuous vegetable (7.8 kg C ha−1). Annual N2O emissions were the highest in rice–vegetable rotation (54.9 kg N ha−1), followed by the continuous vegetable (15.5 kg N ha−1), paddy rice with salinity intrusion (3.3 kg N ha−1), and freshwater rice (2.7 kg N ha−1). The CO2 emissions fluctuate over the year. The paddy rice with salinity intrusion and freshwater paddy rice contribute to sequestration of 2000 kg C ha−1. For continuous vegetable fields, CO2 emissions are positive and higher in the rainy season. The global warming potential obtained highest in salinity intrusion rice paddy as it emits 17,177 kg CO2-eq ha−1 which is as twice the level in freshwater paddy rice (8,389 kg CO2-eq ha−1) and rice–vegetable rotation (8,134 kg CO2-eq ha−1). The continuous vegetable emits about 2,658 kg CO2-eq ha−1. It is recommended to alter the paddy rice with salinity intrusion to other crops for better reduction of greenhouse gas emissions.