Fluxes of greenhouse gases from Andosols under coffee in monoculture or shaded by Inga densiflora in Costa Rica uri icon

abstract

  • The objective of this study was to evaluate the effect of N fertilization and the presence of N-2 fixing leguminous trees on soil fluxes of greenhouse gases. For a one year period, we measured soil fluxes of nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4), related soil parameters (temperature, water-filled pore space, mineral nitrogen content, N mineralization potential) and litterfall in two highly fertilized (250 kg N ha(-1) year(-1)) coffee cultivation: a monoculture (CM) and a culture shaded by the N-2 fixing legume species Inga densiflora (CIn). Nitrogen fertilizer addition significantly influenced N2O emissions with 84% of the annual N2O emitted during the post fertilization periods, and temporarily increased soil respiration and decreased CH4 uptakes. The higher annual N2O emissions from the shaded plantation (5.8 +/- 0.3 kg N ha(-1) year(-1)) when compared to that from the monoculture (4.3 +/- 0.1 kg N ha(-1) year(-1)) was related to the higher N input through litterfall (246 +/- 16 kg N ha(-1) year(-1)) and higher potential soil N mineralization rate (3.7 +/- 0.2 mg N kg(-1) stop d.w. d(-1)) in the shaded cultivation when compared to the monoculture (153 +/- 6.8 kg N ha(-1) year(-1) and 2.2 +/- 0.2 mg N kg(-1) d.w. d(-1)). This confirms that the presence of N-2 fixing shade trees can increase N2O emissions. Annual CO2 and CH4 fluxes of both systems were similar (8.4 +/- 2.6 and 7.5 +/- 2.3 t C-CO2 ha(-1) year(-1), -1.1 +/- 1.5 and 3.3 +/- 1.1 kg C-CH4 ha(-1) year(-1), respectively in the CIn and CM plantations) but, unexpectedly increased during the dry season.

publication date

  • 2008
  • 2008