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- George, T. S., et al.
(författare)
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Organic phosphorus in the terrestrial environment : a perspective on the state of the art and future priorities
- 2018
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Ingår i: Plant and Soil. - : Springer Netherlands. - 0032-079X .- 1573-5036. ; 427:1-2, s. 191-208
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Tidskriftsartikel (refereegranskat)abstract
- Background: The dynamics of phosphorus (P) in the environment is important for regulating nutrient cycles in natural and managed ecosystems and an integral part in assessing biological resilience against environmental change. Organic P (P-o) compounds play key roles in biological and ecosystems function in the terrestrial environment being critical to cell function, growth and reproduction.Scope: We asked a group of experts to consider the global issues associated with P-o in the terrestrial environment, methodological strengths and weaknesses, benefits to be gained from understanding the P-o cycle, and to set priorities for P-o research.Conclusions: We identified seven key opportunities for P-o research including: the need for integrated, quality controlled and functionally based methodologies; assessment of stoichiometry with other elements in organic matter; understanding the dynamics of P-o in natural and managed systems; the role of microorganisms in controlling P-o cycles; the implications of nanoparticles in the environment and the need for better modelling and communication of the research. Each priority is discussed and a statement of intent for the P-o research community is made that highlights there are key contributions to be made toward understanding biogeochemical cycles, dynamics and function of natural ecosystems and the management of agricultural systems.
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| 2. |
- Chen, Z, et al.
(författare)
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Importance of heterotrophic nitrification and dissimilatory nitrate reduction to ammonium in a cropland soil: Evidences from a 15N tracing study to literature synthesis
- 2015
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717 .- 1879-3428. ; 91, s. 65-75
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Tidskriftsartikel (refereegranskat)abstract
- Future climate change is predicted to influence soil moisture regime, a key factor regulating soil nitrogen (N) cycling. To elucidate how soil moisture affects gross N transformation in a cultivated black soil, a 15N tracing study was conducted at 30%, 50% and 70% water-filled pore space (WFPS). While gross mineralization rate of recalcitrant organic N (Nrec) increased from 0.56 to 2.47 mg N kg−1 d−1, the rate of labile organic N mineralization declined from 4.23 to 2.41 mg N kg−1 d−1 with a WFPS increase from 30% to 70%. Similar to total mineralization, no distinct moisture effect was found on total immobilization of ammonium, which primarily entered the Nrec pool. Nitrate (NO3−) was mainly produced via autotrophic nitrification, which was significantly stimulated by increasing WFPS. Unexpectedly, heterotrophic nitrification was observed, with the highest rate of 1.06 mg N kg−1 d−1 at 30% WFPS, contributing 31.8% to total NO3− production, and decreased with WFPS. Dissimilatory nitrate reduction to ammonium (DNRA) increased from near zero (30% WFPS) to 0.26 mg N kg−1 d−1 (70% WFPS), amounting to 16.7–92.9% of NO3− consumption. A literature synthetic analysis from global multiple ecosystems showed that the rates of heterotrophic nitrification and DNRA in test soil were comparative to the forest and grassland ecosystems, and that heterotrophic nitrification was positively correlated with precipitation, soil organic carbon (SOC) and C/N, but negatively with pH and bulk density, while DNRA showed positive relationships with precipitation, clay, SOC, C/NO3− and WFPS. We suggested that low pH and bulk density and high SOC and C/N in test soil might favor heterotrophic nitrification, and that C and NO3− availability together with anaerobic condition were crucial for DNRA. Overall, our study highlights the role of moisture in regulating gross N turnover and the importance of heterotrophic nitrification for NO3− production under low moisture and DNRA for NO3− retention under high moisture in cropland.
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