Regulation of denitrification/ammonia volatilization by periphyton in paddy fields and its promise in rice yield promotion

Abstract

BACKGROUND Nitrogen (N) is the most limiting nutrient in rice production. N loss via denitrification and ammonia (NH3) volatilization decreases N utilization efficiency. The effect of periphyton (a widespread soil surface microbial aggregate in paddy soil) on N‐cycling processes and rice growth in paddy soils remain unclear. The purpose of this study was to reveal the interactions of periphyton with the overlying water and sediment in paddy soils on denitrification/NH3 emissions and rice yield by combining pot experiments and path analysis modeling. RESULTS The sediment exerted significant direct and positive effects on denitrification. The periphyton both directly and indirectly enhanced denitrification, mainly by regulating the ammonium (NH4+)‐N content in the sediment. The total contribution of periphyton to denitrification was stronger than that of the overlying water but smaller than that of the sediment. The pH in the overlying water and the NH4+‐N content in the sediment had a strong positive effect on NH3 volatilization. Although the periphyton biomass and chlorophyll a directly prohibited NH3 emissions, this was counterbalanced by the indirect stimulation effects of the periphyton due to its positive alteration of the pH. Moreover, periphyton facilitated rice yield by 10.2% by releasing N. CONCLUSION Although the periphyton may have driven N loss by regulating the NH4+‐N content in the sediment and the pH in the overlying water, our study also found that the periphyton was considered a temporary N sink and provided a sustained release of N for rice, thus increasing the rice yield. © 2022 Society of Chemical Industry.

Responses of Rice Yield, N Uptake, NH3 and N2O Losses from Reclaimed Saline Soils to Varied N Inputs

“…As for other two stages, the NH 3 volatilization load during BF under the N240 treatment was higher than during SF2, which is similar to the experiment conducted by Wang et al (2012) in non-saline soil [44]. This may be due to the sparse growth of rice in BF and a root system that was insufficient for absorbing N, resulting in a greater loss of NH 3 volatilization, whereas the growth of rice in SF2 was vigorous, and the rice plants directly blocked gas flow and reduced NH 3 volatilization [45,46].…”

Ammonium Adsorption by Surface Sediments in the Loughor Estuary, UK

“…The amount of ammonium adsorption depends on the ion exchange capacity of the sediment which is usually related to organic matter and clay content of the sediments [14]. Therefore, the adsorption of ammonium by the sediments has an important influence on nitrogen cycling [15], which affects not only the diffusive flux of ammonium into the overlying water column but also the coupled nitrification/ denitrification occurring in the sediments.…”