Soil retention of 15N in a simulated N deposition study: effects of live plant and soil organic matter content
2012
Wang, Wenwen | Zhu, Weixing
BACKGROUND AND AIMS: The impacts of atmospheric nitrogen (N) deposition on terrestrial ecosystem processes remain controversial, mostly because of the uncertainty regarding the fates of deposited N. We conducted a 16-week simulated deposition study to experimentally trace N in a greenhouse plant-soil system. METHODS: Using a two-way factorial design, we added (15NH4)2SO4 solution twice a week to pots containing different soil organic matter (SOM) content and with or without a live plant (Salix dasyclados). The recoveries of 15N in soil, plant biomass, and leaching solution were quantified. RESULTS: We found most 15N was retained in soil (18.0–59.2%), with significantly more 15N recovered from high-SOM soils than from low-SOM soils. Plant presence significantly increased 15N retention in soil. Plant biomass accounted for 10–20% of the 15N input, with proportionally more 15N assimilated when plants were grown in low-SOM soils. Leaching loss of 15N was relatively low (10–17%). CONCLUSION: Our study suggests that SOM content and plant presence significantly affect the fates of deposited N. Indeed, N would be preferentially retained in soils with high SOM content and live plant, while plants would assimilate more deposited N when grown in low SOM soils. Global biogeochemical models thus need to incorporate such soil-specific N retention and plant N assimilation.
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