Small-scale heterogeneity in carbon dioxide, nitrous oxide and methane production from aggregates of a cultivated sandy-loam soil

Abstract We developed an automated miniature constant-head tension infiltrometer that measures very small infiltration rates at millimetre resolution with minimal demands on the operator. The infiltrometer is made of 2.9 mm internal radius glass tube, with an integrated bubbling tower to maintain constant negative head and a porous mesh tip to avoid air-entry. In the bubbling tower, bubble formation and release changes the electrical resistance between two electrodes at the air-inlet. Tests were conducted on repacked sieved sands, sandy loam soil and clay loam soil, packed to a soil bulk density ρd of 1200 kg m-3 or 1400 kg m-3 and tested either air-dried or at a water potential ψ of -50 kPa. The change in water volume in the infiltrometer had a linear relationship with the number of bubbles, allowing bubble rate to be converted to infiltration rate. Sorptivity measured with the infiltrometer was similar between replicates and showed expected differences from soil texture and ρd, varying from 0.15 ± 0.01 (s.e.) mm s-1/2 for 1400 kg m-3 clay loam at ψ = -50 kPa to 0.65 ± 0.06 mm s-1/2 for 1200 kg m-3 air dry sandy loam soil. An array of infiltrometers is currently being developed so many measurements can be taken simultaneously.

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Nitrous oxide emissions as affected by liquid and solid pig manures applied to annual and perennial forage crops on a sandy loam soil

Canadian Journal of Soil Science ◽

10.1139/cjss-2015-0052 ◽

2016 ◽

Vol 96 (4) ◽

pp. 361-371 ◽

Cited By ~ 5

Author(s):

Paligwendé Nikièma ◽

O.O. Akinremi ◽

M. Tenuta

Keyword(s):

Nitrous Oxide ◽

Sandy Loam ◽

Sandy Loam Soil ◽

Nitrous Oxide Emissions ◽

Pig Manure ◽

Soil Conditions ◽

Forage Crops ◽

Manure Application ◽

Growing Seasons ◽

Loam Soil

Emissions of nitrous oxide (N2O-N) from manure applied to annual crop (AC) and perennial forage (PF) are poorly quantified for the Canadian Prairie Region. This study used static chambers over two growing seasons to assess soil N2O-N emissions from solid pig manure (SPM) and liquid pig manure (LPM) in AC and PF systems on a sandy loam soil. In 2011, when manure application coincided with hot and wet soil conditions, both manure treatments in AC induced N2O-N emission episodes a week later. In the PF, however, only LPM resulted in an N2O-N emission peak after 8 d. In 2012, manure application did not coincide with hot and wet soil conditions, and emission rates were smaller. Overall, the effect of manure type was inconsistent. In 2011, cumulative emissions in AC from LPM and SPM were 5.8 and 7.8 kg N2O-N ha−1, respectively, and in PF were 10.7 and 0.6 kg N2O-N ha−1, respectively. In 2012, cumulative emissions were <1 kg N2O-N ha−1, except LPM in PF. In 2011, LPM had significantly higher emission factor (EF ≍ 7%) than SPM (≤0.2%) in both AC and PF, whereas in 2012 manure type had no effect on EF (≍ 0). Over the two growing seasons and across manure types, EF did not differ between AC and PF. These results suggest that SPM would reduce N2O-N emission relative to LPM when conditions favor intense denitrification.

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