In:
Journal of Environmental Quality, Wiley, Vol. 45, No. 4 ( 2016-07), p. 1169-1177
Abstract:
Despite increased use of irrigation to improve forage quality and quantity for grazing cattle ( Bos taurus, Linnaeus), there is a lack of data that assess how irrigation practices influence nitrous oxide (N 2 O) emissions from urine‐affected soils. Irrigation effects on soil oxygen (O 2 ) availability, a primary controller of N 2 O fluxes, is poorly understood. It was hypothesized that increased irrigation frequency would result in lower N 2 O emissions by increasing soil moisture and decreasing soil O 2 concentrations. This would favor more N 2 O reduction to dinitrogen (N 2 ). We examined effects of high (3‐d) versus low (6‐d) irrigation frequency with and without bovine urine addition to pasture. Nitrous oxide fluxes were measured daily for 35 d. Soil O 2 , temperature, and water content were continuously measured at multiple depths. Inorganic nitrogen, organic carbon, and soil pH were measured at 6‐d intervals. Measurements of denitrification enzyme activity with and without acetylene inhibition were used to infer the N 2 O/(N 2 O + N 2 ) ratio. The N 2 O/(N 2 O + N 2 ) ratio was lower under high‐ compared with low‐frequency irrigation, suggesting greater potential for N 2 O reduction to N 2 with more frequent irrigation. Although N 2 O fluxes were increased by urine addition, they were not affected by irrigation frequency. Soil O 2 decreased temporarily after urine deposition, but O 2 dynamics did not explain N 2 O dynamics. Relative soil gas diffusivity ( D P / D O ) was a better predictor of N 2 O fluxes than O 2 concentration. On a free‐draining soil, increasing irrigation frequency while providing the same total water volume did not enhance N 2 O emissions under ruminant urine patches in a grazed pasture. Core Ideas Irrigation effects on N 2 O emissions from ruminant urine patches are rarely studied. Irrigation frequency influenced soil oxygen and N 2 O reductase enzyme. N 2 O emission was unaffected by irrigation frequency on a free‐draining soil Soil gas diffusivity ( D P / D O ) was a strong predictor of cumulative N 2 O emissions.
Type of Medium:
Online Resource
ISSN:
0047-2425
,
1537-2537
DOI:
10.2134/jeq2015.10.0516
Language:
English
Publisher:
Wiley
Publication Date:
2016
detail.hit.zdb_id:
120525-0
detail.hit.zdb_id:
2050469-X
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