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Fertilizer Management, Parent Material, and Stand Age Influence Forest Soil Greenhouse Gas Fluxes
Author(s) -
Shrestha Raj K.,
Strahm Brian D.,
Sucre Eric B.,
Holub Scott M.,
Meehan Nathan
Publication year - 2014
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2014.03.0118
Subject(s) - fertilizer , nitrous oxide , urea , zoology , soil water , chemistry , flux (metallurgy) , greenhouse gas , environmental chemistry , environmental science , soil science , ecology , biology , organic chemistry
Impacts of forest management on greenhouse gas (GHG) fluxes have not been well documented. Therefore, we examined GHG fluxes from Pacific Northwest Douglas‐fir [ Pseudotsuga menziesii (Mirb.) Franco] forest soils as affected by fertilizer type (no fertilizer or 224 kg N ha −1 as either urea or coated urea fertilizer [CUF]), stand age (younger vs. older), and parent material (sedimentary vs. volcanic). Following spring fertilization, soil GHG fluxes were measured for four seasons. Daily N 2 O (0.17 mg N 2 O‐N m −2 d −1 ) and CO 2 (2.32 g CO 2 –C m −2 d −1 ) emissions increased with urea application compared with the control (N 2 O: 0.09 mg N 2 O‐N m −2 d −1 ; CO 2 : 1.87 g CO 2 –C m −2 d −1 ); however, CUF did not. Daily CH 4 uptake was inhibited with both urea (0.95 mg CH 4 –C m −2 d −1 ) and CUF (0.91 mg CH 4 –C m −2 d −1 ) compared with the control (1.12 mg CH 4 –C m −2 d −1 ). Nitrous oxide fluxes and CH 4 uptake were greater in older stands. Sedimentary parent material emitted more N 2 O and inhibited CH 4 uptake relative to volcanic parent material. Urea increased annual N 2 O flux by 0.48 kg N 2 O‐N ha −1 yr −1 and CO 2 flux by 1.6 Mg CO 2 –C ha −1 yr −1 and decreased CH 4 uptake by 0.7 kg CH 4 –C ha −1 yr −1 . The global‐warming potential (GWP) after urea and CUF application was 1.7 and 1.1 Mg CO 2 equivalent ha −1 yr −1 , respectively, greater than the unfertilized control for the first year after fertilization. Nitrogen fertilization had little or no effect on GWP when considered the added growth benefit from fertilization.