Three-dimensional spatial variability in soil microorganisms of nitrification and denitrification at a row-transect scale in a tea field

The recent boom of the tea industry in southern China is associated with large inputs of nitrogen (N) fertilizers and the significant emissions of nitrous oxide (N2O), and leads to investigation of mitigation options. In this study, three-dimensional (3D) geostatistics was applied at a tea row-transect scale to investigate the spatial distributions of N2O producers (ammonia oxidizers: AOA and AOB, denitrifiers: narG-type and nosZ-type) in a tea field in southern China. Our results showed that most of AOA, AOB, and denitrifiers of narG-type and nosZ-type concentrated in the topsoil at 0-20 cm. Soil depth was found a main factor to influence the spatial distributions of nitrifiers and denitrifiers, which were well-described by a Boltzmann sigmoidal equation with half-maximum coefficients ranging from 7 to 16 cm. Effective spatial ranges for log10-transformed AOA, AOB, and denitrifiers of narG-type and nosZ-type were 50.2 cm, 92.8 cm, 35.6 cm, and 20.4 cm, respectively. The predicted 3D spatial distributions of AOA, AOB, and narG-type denitrifier were smooth, while a patchy distribution along the rhizosphere was observed for nosZ-type denitrifiers.