Nitrous Oxide Emission from Fertilized Soils: An Analytical Review

Soils are among the main biological sources of nitrous oxide (N2O), and nitrification and denitrification processes are the major N2O production factors in soils. The nitrogen of mineral and organic fertilizers applied to the fields is easily involved in the biogeochemical cycle of soil nitrogen and contributes to the N2O emission to the atmosphere. A longer lifetime (121 years) of nitrous oxide and a higher global warming potential as compared with CO2 and CH4 are responsible for its high importance in the greenhouse effect. An increase in the N2O concentrations enhances the destruction of the ozone layer. To evaluate the regional contributions of agricultural soils to the total world greenhouse gas emissions, the Intergovernmental Panel on Climate Change (IPCC) recommends using emission factors (EFN2O) for national N2O inventories. The EFN2O value depends on many factors, including soil and climatic conditions, type of mineral fertilizer, organic amendments, and nitrogen-containing waste. The data on the direct measurements of N2O emission from soils in Russia are rather limited and the estimates for N2O emission from soils for The Russian National Greenhouse Gas Inventory rely on the data calculated according to the IPCC Guidelines. The nitrogen budget in the Russian agriculture in the past 25 years has been sharply deficient. This means that a considerable part of the crop yield is formed at the expense of mineralized soil nitrogen, which is quickly assimilated by plants and microorganisms and almost does not accumulate in a free state. The estimated EFN2O value for fertilized cereal crops (22-27 million hectares) and cereal crops is 0.66-0.70 and 0.54-2.56, which is considerably lower as compared with the IPCC default (1.0) recommended for ecologically permissible level of fertilizer nitrogen.