Land use change and biogeochemical controls of nitrogen oxide emissions from soils in eastern Amazonia

Abstract

Abstract. The objectives of this study were (1) to determine the effects of land use change on N oxide fluxes from soil in seasonally dry, eastern Amazonia and (2) evaluate the "hole-in-the-pipe" model in a field setting where N availability varies among land uses and soil moisture varies among seasons. We measured N oxide flux from an old-growth forest, a 20-year-old secondary forest, an active pasture, and a degraded pasture. We also measured soil water content, soil inorganic N stocks, net N mineralization and nitrification potential. To determine the effects of pasture age on N oxide flux, we measured gas fluxes at a chronosequence of pastures (0-13 years).In the land use study, N20 fluxes followed the order: primary forest (

Landscape and Regional Scale Studies of Nitrogen Gas Fluxes

“…It is important to note that hole-in-the-pipe type modeling is ongoing at many sites around the world, providing many opportunities for comparison and synthesis (Verchot et al 1999, Davidson et al 2000.…”

Potential N2O emissions from leguminous tree plantation soils in the humid tropics

“…[11] We calculated the minimum significant flux (a = 0.05 [Hutchinson and Livingston, 1993;Verchot et al, 1999;Ishizuka et al, 2005b]) from verification of each chamber flux. The minimum flux considered significantly different from zero was 37 mg N m À2 d À1 .…”

“…[20] Annual N 2 O emissions from secondary forest soils (0.33 kg N ha À1 ) are low relative to other tropical forests; e.g., tropical forest emissions are estimated at 0.01 -7.68 kg N ha À1 [Breuer et al, 2000] and Amazon secondary forests at 0.94 kg N ha À1 [Verchot et al, 1999] or 0.80 kg N ha À1 [Palm et al, 2002]. These low secondary forest emissions are comparable to those observed at primary forests in central Sumatra (0.13 kg N ha À1 and 0.39 kg N ha À1 [Ishizuka et al, 2002]), but relatively low compared to emissions from southern Sumatra forests (1.47 and 1.80 kg N ha À1 at sites showing high WFPS (90 -100% [Verchot et al, 2006]) and montane forests in central Sulawesi (0.29, 1.01, and 1.11 kg N ha À1 [Purbopuspito et al, 2006]).…”

Nitric oxide emissions from black soil, northeastern China: A laboratory study revealing significantly lower rates than hitherto reported

“…For example, a laboratory study showed an optimum soil moisture of about 20% WFPS (Yang and Meixner, 1997), but in another study conducted in saline sodic soil of northeastern China, maximum NO fluxes was observed at approximately 9.5%e18% WFPS (Yu et al, 2008). The optimum value was even discovered to be approximately 50% WFPS in a seasonally dry forest of the eastern Amazon (Verchot et al, 1999). In this study, the optimum soil moisture for black soil NO emission was approximately 25.7%.…”

“…Many studies have shown that an optimum soil moisture does exist for soil NO emissions (Otter et al, 1999;Verchot et al, 1999;Yang and Meixner, 1997;Yu et al, 2008), but the value varied with soils. For example, a laboratory study showed an optimum soil moisture of about 20% WFPS (Yang and Meixner, 1997), but in another study conducted in saline sodic soil of northeastern China, maximum NO fluxes was observed at approximately 9.5%e18% WFPS (Yu et al, 2008).…”