1 / 13

Impact of long-term N fertilisation on C stocks in trees and soils in northern Europe

Impact of long-term N fertilisation on C stocks in trees and soils in northern Europe. Riitta Hyvönen, Tryggve Persson, Stefan Andersson, Bengt Olsson, Göran Ågren & Sune Linder Biogeochemistry (Online). Objectives.

zulema
Download Presentation

Impact of long-term N fertilisation on C stocks in trees and soils in northern Europe

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Impact of long-term N fertilisation on C stocks in trees and soils in northern Europe Riitta Hyvönen, Tryggve Persson, Stefan Andersson, Bengt Olsson, Göran Ågren & Sune Linder Biogeochemistry (Online)

  2. Objectives • To determine the efficiency of added N on C storage in trees and soils in 15 long-term experiments in Sweden and Finland • To use data on N-use efficiency to draw conclusions about the role of 100 years of N deposition on C stocks

  3. Methods • Long-term (14-30 yrs) experiments with repeated (3-30 times) addition of N and/or NPK in doses of 30-200 kg N ha-1 occasion-1. • Tree biomass: Stem diam, no. of trees ha-1 and Marklund (1988) expansion factors, C=50% of dry wt • Soil sampling: Organic layer + 0-10 cm min. soil on, at least, one occasion

  4. Tree biomass C (above and below ground) in control plots (0) and after annual additions of ammonium nitrate (N), potassium and phosphorus (PK) or NPK at different doses (N1=33, N2=67, N3=109 kg N ha-1 yr-1) at two sites.

  5. Cum. increase in tree biomass C in excess of control plots as a function of the cumulative amount of N added. N1=33, N2=67, N3=109 kg N ha-1 yr-1. Conclusion: Low application doses of N more efficient to sequester C than high N doses. Example: 35, 17, 9 kg (C) kg-1 (N) for N1, N2 and N3, respectively, at Norrliden).

  6. N-use efficiency for C sequestration in tree biomass as a function of C/N ratios in humus layers of control plots after addition of N (left) or NPK (right) fertiliser at P. abies (PA) and Pinus sylvestris (PS) sites. Conclusion: Soil N status (C/N) seems to regulate N-use efficiency in trees, but low C/N ratio often reflects low availability of P and K as seen by NPK addition.

  7. N-use efficiency for C sequestration in soil (org. layer + 0-10 cm min. soil) as a function of C/N ratios in humus layers of control plots after addition of N or NPK fertilisers

  8. Relationship between N-use efficiencies in trees and soils for P. abies and P. sylvestris sites with both tree and soil studies. Figures from both N and NPK fertilisation.Conclusion: (1) Higher SOC seq. in P abies than in P sylvestris soils. (2) High SOC seq. also when trees don´t sequester extra C indicates reduced decomposition.

  9. Mean (SE, n=4) C pools, C mineralisation rates (at 15°C) and calculated field Rh to a depth of 10 cm in the mineral soil at Stråsan in control (0) and N-fertilised (N1) treatments in 2004. N1 had received, on average, 33 kg N ha-1 y-1 during 39 yrs.

  10. Estimates of cumulative N deposition in S and N Sweden during 1900-2000 and resulting tree and soil C pools as calculated from the N-use efficiencies

  11. Mean SOC content (±95% c.i.) for forest floor and total soil at dry and mesic forest sites in southern (55-60 oN, n= 445), central (60 – 64 oN, n=448) and northern Sweden (64-68 oN, n=329). After Mats Olsson, pers. comm.

  12. Conclusions • N-use efficiencies for trees (P abies) varied (0-50 kg (C) kg-1 (N)) depending on C/N ratio and PK availability. • N-use efficiencies for SOC was generally lower than for trees and averaged 13 kg (C) kg-1 (N)) for P abies and 7 for P sylvestris. • 10 kg N ha-1 yr-1 higher N deposition in S than in N Sweden for a whole century should have resulted in 2.0±1.0 kg m-2 more tree C and 1.3±0.5 kg m-2 more SOC.

More Related