Short‐range spatial variation of nitrous oxide fluxes in relation to compaction and straw residues

Abstract

Summary The spatial heterogeneity of N2O flux at short distances (0.1–2 m) was characterized in relation to various soil physical and chemical properties and the location of incorporated crop residues in arable soils. Plots were prepared with uniform compaction (either zero or compacted by a laden two‐wheel‐drive tractor) in two field experiments, one under winter barley (Hordeum vulgare), the other under oil‐seed rape (Brassica napus). Flux measurements were made of N2O using small chambers (7.3 cm diameter) placed at intervals of approximately 10 cm along a transect (c. 2 m long) across the direction of application of the treatments of compaction and residue incorporation. The flux of N2O and many other measurements showed large variation over short distances, particularly when fluxes were small. The spatial variation of the flux was not closely related to the soil properties. Correlations showed that cone resistance, air permeability and closeness to incorporated residues were as important as soil NO3, NH4 and soluble C in determining flux of N2O from non‐compacted soils. Most properties of compacted soils did not correlate with N2O flux. Correlation and multiple regression analysis failed to establish consistent relations between soil environmental variables and N2O flux, but principal component regression indicated that, overall, N2O flux increased with decreasing distance from straw residues and air permeability, and with increasing cone resistance and wet bulk density.

Seasonal variation in N2O emissions from urine patches: Effects of urine concentration, soil compaction and dung

“…However, there is little data to indicate to what extent these increases in N 2 O emissions will occur under field conditions. Ball et al (2000) could only detect a weak relationship between cone resistance and N 2 O emissions in the field. Hansen et al (1993) reported an increase in N 2 O emissions for fertilizer from 3.9% to 5.3% due to compaction.…”

Toward Improved Coefficients for Predicting Direct N2O Emissions from Soil in Canadian Agroecosystems

“…For example, in some studies one 'measurement' refers to the mean cumulative flux calculated for flux determinations on 36 days from April through October in a given year for one field treatment (4 replicates); in other studies it might refer to cumulative flux calculated from determinations on 30 sampling days during an entire year. N 2 O emissions are inherently variable (Grant and Pattey 1999;Ball et al 2000;Yanai et al 2003;Sˇimek et al 2004). As such, we did not exclude 'outliers' in the data set, except in two extreme cases.…”

Weed Responses to Soil Compaction and Crop Management

“…Decrease of nitrogen content in plant dry matter in wet years, especially in 2001 and 2004, was probably connected next to poorer root development also with increased denitrification and decreased mineralization of organic matter in highly compacted soil due to decreased soil aeration. N 2 O flux increases with decreasing distance from straw residues and air permeability, and with increasing cone resistance and wet bulk density (Ball et al, 2000).…”

“…There is also an interaction between compaction and soil water content. Carbon mineralization increases with increasing water content in loose soil but decreases in compact soil (Ball et al, 2000) and may increase the total amount of nutrients in soil. There is an increased the amount of total N in the compacted soil, as total N content in soil is connected with organic C content.…”