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| Net nitrogen mineralization and nitrification in the tidal marsh soils of the Yellow River Estuary |
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Abstract The dynamics of inorganic N pool, N net mineralization/nitrification rates, and their affecting factors in the tidal marsh soils in the Yellow River Estuary were investigated by an in situ incubation approach with top-closed PVC tubes. Results showed that soil inorganic N concentrations in the high marsh (LW), middle marsh (JP1) and low marsh (JP2) had significantly dynamic characteristics. The NH4+-N concentrations were the highest in LW, in the order of LW＞JP1＞JP2, while NO3--N concentrations presented JP1＞LW＞JP2. The soil N net mineralization/nitrification rates in the three marshes showed a clear seasonal dynamics. The net mineralized N in LW, JP1 and JP2 in the growing season were 27.81, 11.90 and 0.33kg/hm2, the net nitrified N were 12.09, 15.99 and 1.19kg/hm2, and the percentage of nitrified N in mineralized N were 43.47%, 100.00% and 100.00%, respectively. The net mineralized N was significantly correlated with soil water content, while the net nitrified N was significantly correlated with soil pH. The inorganic N-maintaining capacity of the three marshes presented LW＞JP1＞JP2, suggesting that, from the standpoint of N cycling, the high marsh was more stable, while the stability of low marsh were the lowest.
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Received: 30 September 2014
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