Spatial Variability of Nitrous Oxide Fluxes and Controlling Soil and Topographic Properties

Abstract

Spatial heterogeneity of nitrous oxide (N2O) flux was characterized along with various soil chemical, physical, and microtopographical properties to identify those determining flux in fertilized grassland in spring 1993 and in fertilized winter wheat in spring 1994. Measurements were made at random locations within regular grids. Nitrous oxide emission was measured using closed chambers at 84 locations in each grid, spread over 2 d. The ranges of emissions from the grassland and from the winter wheat were 0 to 134 and 0 to 26.4 g N2O‐N ha−1 d−1. Variograms for N2O emission and for concentrations in the soil atmosphere at 100 mm depth indicated that spatial dependence was weak at both sites. Of the other properties, pH and nitrate showed weak autocorrelation but none of the soil physical properties showed any significant spatial dependence. The results of multiple linear regression suggested that denitrification was the main N2O production process at the grassland site, but nitrification may have been equally important at the drier winter wheat site. At both sites, the highest N2O emissions were associated with areas of a few square centimeters to a few square meters, lying below the average slope. Use of a partial least squares regression technique to predict nitrous oxide flux revealed the contribution of air permeability in addition to nitrate, ammonium, and soil water contents. Our analyses suggested that nitrous oxide production, consumption, and transport processes varied markedly with depth (over a few centimeters) near the soil surface.

Spatio-temporal variability in N<sub>2</sub>O emissions from a tea-planted soil in subtropical central China

“…In this study, the median (13.6 mg N m −2 d −1 ) and CV (143 %) of N 2 O fluxes measured in the tea field were all found to be higher than those in other agricultural systems, such as grasslands (Ambus and Christensen, 1994;Turner et al, 2008),winter wheat (Ball et al, 1997;Clemens et al, 1999;Mathieu et al, 2006), and summer maize (Clemens et al, 1999); the findings were similar to the results for the wet season reported by Fu et al (2015), predominantly because of the optimal conditions for soil microbe activity…”

“…Our findings were similar to those of Fu et al (2015) for a fertilized tea field during the wet season. As in other agricultural soils (Ball et al, 1997;Mathieu et al, 2006;Yanai et al, 2003), fertilization contributes to the spatial pattern of the N 2 O fluxes from the tea-planted fields, with the highest average fluxes being observed at the fertilization points . With regard to rainfall, it is possible that rainfall affects 5 the soil moisture and then regulates the variations in the availability of oxygen in tea planted soils, thereby causing spatio-temporal heterogeneity in N 2 O emissions by inducing different degrees of soil nitrification and denitrification (Firestone and Davidson, 1989;Fu et al, 2015;Konda et al, 2010).…”

“…To obtain complete information regarding N 2 O emissions from soils, clas-5 sical continuous temporal observations using static box methods and micro meteorological methods (Davidson et al, 1993(Davidson et al, , 2000, as well as purely spatial-structure-based research (Ball et al, 1997;Clemens et al, 1999;Röver et al, 1999;Folorunso et al, 1984;Li et al, 2013) have been applied in recent decades and have yielded significant results. However, these studies failed to provide a sufficient description of the process 10 of the evolution of N 2 O emissions over space and time .…”

Greenhouse Gas Emissions from Housing and Manure Management Systems at Confined Livestock Operations

“…The availability of N (NH4 + and NO3 -) [43,49,50], and the factors that alter the redox potential of the soil, such as changes in soil moisture [51][52][53], soil texture, and organic C, have major effects on the production of N2O in soils. In addition, several soil management practices such as tillage, soil compaction [54][55], irrigation, and drainage affect the production and transport of N2O release by influencing the physical condition of the soils such as aeration and soil water content.…”

Automated sampling system for long-term monitoring of nitrous oxide and methane fluxes from soils

“…Greenhouse gas fluxes from soils, particularly those of nitrous oxide (N 2 O), show large spatial variability (Ball et al 1997;Yanai et al 2003) and temporal variability (e.g. Akiyama et al 2000).…”