Quantification of priming and CO2 emission sources following the application of different slurry particle size fractions to a grassland soil

The highest emissions of CO2 from soils and most pronounced priming effect (PE) from soils generally occur immediately after slurry application. However, the influence of different particle size slurry fractions on net soil C respiration dynamics and PE has not been studied. Therefore, a slurry separation technique based on particle sizes was used in the present study. Six distinct fractions (>2000, 425–2000, 250–425, 150–250, 45–150, 250 μm fractions. The overall contribution of slurry C to total CO2 emissions was higher in smaller slurry particle size treatments in the first days after application. The addition of the various slurry fractions to soil caused both significant positive and negative PEs on the soil organic matter mineralization. The timing and type (positive or negative) of PE depended on the slurry particle size. Clearly, farm based separation pre-treatment leading to two or more fractions with different particle sizes has also the potential to reduce or modify short-term CO2 emissions immediately after slurry application to soil