Premium
Greenhouse gas fluxes from an Australian subtropical cropland under long‐term contrasting management regimes
Author(s) -
WANG WEIJIN,
DALAL RAM C.,
REEVES STEVEN H.,
BUTTERBACHBAHL KLAUS,
KIESE RALF
Publication year - 2011
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2011.02458.x
Subject(s) - greenhouse gas , environmental science , tillage , soil water , subtropics , fertilizer , conventional tillage , soil carbon , agronomy , nitrogen , zoology , atmospheric sciences , hydrology (agriculture) , soil science , ecology , chemistry , biology , geotechnical engineering , organic chemistry , engineering , geology
AbstractThe long‐term effects of conservation management practices on greenhouse gas fluxes from tropical/subtropical croplands remain to be uncertain. Using both manual and automatic sampling chambers, we measured N 2 O and CH 4 fluxes at a long‐term experimental site (1968–present) in Queensland, Australia from 2006 to 2009. Annual net greenhouse gas fluxes (NGGF) were calculated from the 3‐year mean N 2 O and CH 4 fluxes and the long‐term soil organic carbon changes. N 2 O emissions exhibited clear daily, seasonal and interannual variations, highlighting the importance of whole‐year measurement over multiple years for obtaining temporally representative annual emissions. Averaged over 3 years, annual N 2 O emissions from the unfertilized and fertilized soils (90 kg N ha −1 yr −1 as urea) amounted to 138 and 902 g N ha −1 , respectively. The average annual N 2 O emissions from the fertilized soil were 388 g N ha −1 lower under no‐till (NT) than under conventional tillage (CT) and 259 g N ha −1 higher under stubble retention (SR) than under stubble burning (SB). Annual N 2 O emissions from the unfertilized soil were similar between the contrasting tillage and stubble management practices. The average emission factors of fertilizer N were 0.91%, 1.20%, 0.52% and 0.77% for the CT‐SB, CT‐SR, NT‐SB and NT‐SR treatments, respectively. Annual CH 4 fluxes from the soil were very small (−200–300 g CH 4 ha −1 yr −1 ) with no significant difference between treatments. The NGGF were 277–350 kg CO 2 ‐e ha −1 yr −1 for the unfertilized treatments and 401–710 kg CO 2 ‐e ha −1 yr −1 for the fertilized treatments. Among the fertilized treatments, N 2 O emissions accounted for 52–97% of NGGF and NT‐SR resulted in the lowest NGGF (401 kg CO 2 ‐e ha −1 yr −1 or 140 kg CO 2 ‐e t −1 grain). Therefore, NT‐SR with improved N fertilizer management practices was considered the most promising management regime for simultaneously achieving maximal yield and minimal NGGF.