Nitrous Oxide Emissions from In Situ Deposition of 15N‐Labeled Ryegrass Litter in a Pasture Soil. Issue 2 (1st March 2013)

• Record Type: Journal Article
• Authors: Pal, Pranoy; Clough, Tim J.; Kelliher, Francis M.; Sherlock, Robert R.
• Is Part Of: Journal of Environmental Quality. Volume 42:Issue 2(2013)
• Page Start: 323
• Page End: 331
• Publication Date: 2013-03-01
• Subjects: Agricultural ecology -- Periodicals; Environmental engineering -- Periodicals; Pollution -- Periodicals; 630
• DOI: 10.2134/jeq2012.0271
• Languages: English
• ISSNs: 0047-2425

Abstract

Abstract : During pasture grazing, freshly harvested herbage (litterfall) is dropped onto soils from the mouths of dairy cattle, potentially inducing nitrous oxide (N2 O) emissions. Although the Intergovernmental Panel on Climate Change (IPCC) recommends accounting for N2 O emissions from arable crop residues in national inventories, emissions from the litterfall of grazed pasture systems are not recognized. The objective of this study was to investigate the potential of litterfall to contribute to N2 O emissions in a field study located on a pasture site in Canterbury, New Zealand (43°38.50′ S, 172°27.17′ E). We applied 15 N‐labeled perennial ryegrass ( Lolium perenne L.) to the surface of a pastoral soil (Temuka clay loam) and, for up to 139 d thereafter, quantified the contribution of herbage decomposition to N2 O production and soil N dynamics. Litterfall contributed to the 15 N enrichment of soil NO3 –N and N2 O–N pools. After 49 d, 15 N recovery as N2 O equated to 0.93% of the surface‐applied litter 15 N, with 38 to 75% of the cumulative N2 O flux occurring within 4 to 10 d of treatment application. Emissions of N2 O likely resulted from ammonification followed by a coupling of nitrification and denitrification during litter decomposition on the soil surface. The emission factor of the litter deposited in situ was 1.2 ± 0.2%, which is not substantially greater than the IPCC default emission factor value of 1% for crop residues. Further in situ studies using different pasture species and litterfall rates are required to understand the microbial processes responsible for litter‐induced N2 O emissions.