Spatial and Temporal Distributions of Soil Organic Carbon and Total Nitrogen in Two Marsh Wetlands with Different Flooding Frequencies of the Yellow River Delta, China

A field study was carried out in two typical marsh wetlands (Sites A and B) with different flooding frequencies in the Yellow River Delta of China in three different dates to investigate spatial and temporal distributions of soil organic carbon (SOC) and total nitrogen (TN) along the distance away from one tidal creek and the Yellow River, respectively. The results showed that SOC and TN contents and densities generally decreased with depth, except for an obvious accumulation peak of TN at the 2040?cm soil layer; and they had higher heterogeneity at both Sites A and B; However, SOC and TN contents and densities showed different spatial distribution patterns at both sites in different sampling dates. Generally, SOC and TN contents in marsh soils were higher at Site A than those at Site B. TN was significantly correlated with available phosphorous, SOC, and the carbon/nitrogen (C/N) ratio at both sites, whereas SOC was significantly correlated with soil depth, soil moisture and salinity at both sites. Additionally, the C/N ratios were higher at Site B than those at Site A, and they were significantly correlated with soil moisture (Site A), bulk density, and TN (Sites A and B).