Nitrous Oxide Emissions from an Ultisol of the Humid Tropics under Maize–Groundnut Rotation

Abstract

Nitrous oxide (N20) contributes to global climate change and agricultural soils seem to be the major source. Lack of information led to this study on the influence of different amounts and sources of nitrogen on N2O emission from a maize (Zea mays L.)-groundnut (Arachis hypogae L.) crop rotation in an Ultisol of the humid tropics. The treatments were: inorganic N + crop residues (NC), inorganic N only (RN), and half of inorganic N + crop residues + chicken manure (NCM). The corresponding amount of N applied was 322, 180, and 400 kg ha(-1) yr(-1), respectively. The N2O emissions depended on the amounts and types of N. A maximum peak (9,889 +/- 2,106 microg N2O-N m(-2) d(-1)) was detected at 2 wk before maize sowing amended with chicken manure, showing a persistent influence on N transformations and N2O release. The mineral N from either applied source became low by 2 to 4 wk, coinciding with the small N2O fluxes or its consumption to a few isolated instances. The N2O flux significantly correlated with the mineral N and water-filled pore spaces. The direct annual N2O emission was 3.94 +/- 0.23, 1.90 +/- 0.08, and 1.41 +/- 0.07 kg N2O-N ha(-1) from the NCM, NC, and RN treatments, respectively. The corresponding N2O-N loss of the applied N plus N fixed by groundnut was 0.83, 0.49, and 0.59%. Overestimations of direct annual N2O emission using the Intergovernmental Panel on Climate Change (IPCC) methodology suggest a location-specific emission factor for variable N sources to be considered.

Methane and Nitrous Oxide Emission from <i>Kharif</i> Rice Field as Influenced by Nutrients and Moisture Regimes in New Alluvial Agroclimatic Region of West Bengal

“…A negative value indicates low N 2 O emission, where gradient of slope is less. These views are supported by other researchers as well 16,17 . Table 1).…”

Emissions of Nitrous Oxide (N2O) and Di-Nitrogen (N2) from the Agricultural Landscapes, Sources, Sinks, and Factors Affecting N2O and N2 Ratios

“…3.2.1) especially nitrous oxide reductase is reported to be sensitive to soil O 2 level, while anaerobic soils and sediments will generate both N 2 O and N 2 . A number of studies have reported higher amounts of N 2 than N 2 O at lower O 2 partial pressure and WFPS above 70% (Eriksen & Hartwig, 1993;Dendooven et al, 1999;Kwong et al 1999, Khalil et al, 2002. Aulakh et al (2001) reported that gaseous N losses as N 2 O after application of urea (120 kg ha -1 ) to flooded rice were 8 to 10 times higher than those of upland wheat because of the anaerobic conditions in the former.…”

“…These areas include; urine patches in grazed pastures, where up to 1,000 kg N ha -1 can be found Zaman & Blennerhassett., 2010), riparian wetlands (Nguyen et al, 1999;Matheson et al, 2003), drains and ditches, and stream or river channels (Garcia-Ruiz et al, 1998;Bronson & Fillery, 1998;Mcmahon & Dennehy, 1999;Walker et al, 2002;Zaman et al, 2008b&c, Zaman & Nguyen, 2010. However denitrification can also occur in less obviously waterlogged areas within the agricultural landscape due to the existence of anaerobic microsites such as in the center of soil aggregates (Parkin, 1987) or in areas of localized high O 2 consumption (hot spots), which are created by decaying organic C (Burton et al, 1999;Godde & Conrad, 2000;Khalil et al, 2002;Mosier et al, 2002). Depending on soil physical and chemical conditions, other processes like chemo-denitrification can result in substantial production of N 2 O.…”

“…Denitrification becomes a major source of N 2 O and N 2 production at lower O 2 partial pressure (<0.5 vol. %) and higher WFPS (>60%) (Davidson, 1993;Scholefield et al, 1997;Bronson & Fillery, 1998;Khalil et al, 2002). In such scenarios, more aerobic soils are likely to produce mainly N 2 O because denitrification reductases (Eq.…”

Effect of soil amendments on greenhouse gas emissions from subtropical soils

“…However, annual rainfall in their study was much lower (~700 mm) compared to the study presented here (1292 mm). Khalil et al (2002) reported cumulative N2O emissions of 0.83% per total N applied (400 kg N ha -1 ) from chicken manure application in Malaysia (annual rainfall: 2293 mm), but the manure was applied in combination with inorganic N in this study.…”