Effects of Arbuscular Mycorrhizal Fungi on N2O Emissions from Rice Paddies
2015
Zhang, Xue | Wang, Li | Ma, Fang | Shan, Dan
Arbuscular mycorrhizal fungi (AMF) can alter the dynamics of soluble nitrogen in paddy field soils by promoting nitrogen assimilation by rice. However, it is unknown whether this affects N₂O emissions from rice paddies. This study was designed to assess the effects of AMF on N₂O emissions by analyzing the relationships between AMF and the parameters affecting N₂O emissions. Path analysis was used to quantitatively partition the direct and indirect effects of different parameters on N₂O emissions. Results showed that N₂O emissions were controlled by environmental pathways (transpiration, evaporation, and precipitation affecting soil water content) and biotic pathways (soluble nitrogen assimilation by the rice, which varies according to rice biomass). Under different water conditions, the contributions of the two pathways to N₂O emissions varied strongly. During the flooding stage, the environmental pathways were dominant, but inoculation with AMF promoted the contribution of the biotic pathway to the reduction of N₂O emissions. During the draining stage, the environmental pathways were dominant in the non-inoculated treatment, but inoculation made the biotic pathways dominant by increasing the biomass of rice. During the growing stage, N₂O emissions from inoculated soil (17.9–492.9 μg N₂O-N m⁻² h⁻¹) were significantly lower than those in non-inoculated soil (22.1–553.1 μg N₂O-N m⁻² h⁻¹; p < 0.05). Consequently, inoculating with AMF has the potential for mitigating N₂O emissions from rice paddies.
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