Indirect nitrogen losses of managed soils contributing to greenhouse emissions of agricultural areas in Austria: results from lysimeter studies

Abstract

A considerable share of greenhouse gas emissions, especially N2O, is caused by agriculture, part of which can be attributed to indirect soil emissions via leaching and runoff. Countries have to report their annual emissions, which are usually calculated by using the default value of 0.3 for FracLEACH, a factor that represents the fraction of nitrogen losses compared to total nitrogen inputs and sources. In our study we used 22 lysimeters, covering a wide range of soils, climatic conditions and management practices in Austria, to evaluate nitrogen losses through leaching and to calculate FracLEACH. The terms of the nitrogen mass balance of the lysimeters were directly measured for several years. Both grassland and arable land plots gave significantly smaller values of FracLEACH than the default value. For grassland, FracLEACH values of only 0.02 were found which varied very little over the entire observation period. For arable sites, FracLEACH values were higher (around 0.25) and showed significant variability between years due to variations in crop rotation, fertilization rates, and yields.