Emissions of nitrous oxide from boreal agricultural mineral soils-statistical models based on measurements.

摘要

This study compiles data of nitrous oxide (N₂O) emissions from 13 fields on mineral soils in Finland with differing soil type, crop and management. Measurements using the chamber technique were conducted for periods of 1-3 years on each field in 2000-2009. The annual emissions varied between 0.12 and 12 kg N₂O-N ha-1 yr-1 and the emission rates were higher for annual compared to perennial crops. Statistical mixed models were derived based on the measured emissions of N₂O and background variables. Environmental and management data available for the analysis were the crop, fertilizer rate, type of fertilizer, soil characteristics and weather data. Models with the fertilizer rate and type of crop (annual/perennial) as variables were selected as the simplest method to estimate the flux of N₂O from mineral agricultural soils. The effect of fertilizer type (mineral/organic) can be added to obtain a more detailed model. In the case of manures, the amount of mineral nitrogen was better related to N₂O flux than the amount of total nitrogen. These models give realistic estimates of N₂O fluxes in boreal conditions with frozen soils in the winter, frequently renewed grasslands and spring-sown crops as majority of the annual crops.