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Cover Crop Effects on Nitrous Oxide Emissions: Role of Mineralizable Carbon
Author(s) -
Mitchell David C.,
Castellano Michael J.,
Sawyer John E.,
Pantoja Jose
Publication year - 2013
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2013.02.0074
Subject(s) - cover crop , nitrous oxide , agronomy , environmental science , secale , fertilizer , soil water , greenhouse gas , crop residue , denitrification , nitrogen , agriculture , chemistry , soil science , biology , ecology , organic chemistry
Nitrous oxide (N 2 O) emission from denitrification in agricultural soils often increases with N fertilizer and soil nitrate (NO 3 ) concentrations. Overwintering cover crops in cereal rotations can decrease soil NO 3 concentrations and may decrease N 2 O emissions. However, mineralizable C availability can be a more important control on N 2 O emission than NO 3 concentration in fertilized soils, and cover crop residue provides mineralizable C input. We measured the effect of a winter rye ( Secale cereale L.) cover crop on soil N 2 O emissions from a maize ( Zea mays L.) cropping system treated with banded N fertilizer at three rates (0, 135, and 225 kg N ha –1 ) in Iowa. In addition, we conducted laboratory incubations to determine if potential N 2 O emissions were limited by mineralizable C or NO 3 at these N rates. The rye cover crop decreased soil NO 3 concentrations at all N rates. Although the cover crop decreased N 2 O emissions when no N fertilizer was applied, it increased N 2 O emissions at an N rate near the economic optimum. In laboratory incubations, N 2 O emissions from soils from fertilizer bands did not increase with added NO 3 , but did increase with added glucose. These results show that mineralizable C availability can control N 2 O emissions, indicating that C from cover crop residue increased N 2 O emissions from fertilizer band soils in the field. Mineralizable C availability should be considered in future evaluations of cover crop effects on N 2 O emissions, especially as cover crops are evaluated as a strategy to mitigate agricultural greenhouse gas emissions.