Spatial distribution patterns of nitrate nitrogen and ammonia nitrogen were studied in the tidal marsh soils of the Yellow River Delta by geo-statistical methods.The results showed that the NO3--N and NH4+-N contents had significant horizontal variability in different soil layers

which was mainly correlated with their active physical transport characteristics caused by the better water conditions in the tidal marsh.The horizontal distribution of NO3--N in topsoil displayed significant spatial structure

which can be best fitted with Gaussian model and had moderate spatial correlation.The natural structure factors had significant effects on the spatial variability

while the effects of random factors were relatively low.The maximum spatial variability of NO3--N in topsoil was observed in the direction extending towards the low tidal marsh

showing a great effect by the ebbs and flows of tide.The spatial distribution patterns of NO3--N in topsoil were significant.The lowNO3--N contents in topsoil were generally observed on the sites close to low tidal marshes

while the high values appeared on the edges of the study area.This study indicated that micro-physiognomy characteristics and tidal micro-domain physical disturbance were the two most important random factors inducing spatial heterogeneity

while water and salinity conditions

soil types and tidal circulation were three important structure factors.