Denitrification and nitrous oxide to nitrous oxide plus dinitrogen ratios in the soil profile under three tillage systems

• Published in: Biology and fertility of soils Vol. 38; no. 6; pp. 340 - 348
• Main Authors: ELMI, Abdirashid A, MADRAMOOTOO, Chandra, HAMEL, Chantal, AIGUO LIU
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01-10-2003; Springer Nature B.V
• Subjects: Agricultural practices; Agronomy. Soil science and plant productions; Biological and medical sciences; Carbon; Crop residues; Denitrification; Fundamental and applied biological sciences. Psychology; Nitrous oxide; Sandy loam; Soil conservation; Soil depth; Soil profiles; Soil science; Soil surfaces; Soils; Tillage; SOIL BIOLOGY; Mole fraction; Denitrification; Soil science; Nitrous oxide production; Nitrogen protoxide; Soil profile
• ISSN: 0178-2762; 1432-0789
• DOI: 10.1007/s00374-003-0663-9

There is a growing interest in the adoption of conservation tillage systems [no-till (NT) and reduced tillage (RT)] as alternatives to conventional tillage (CT) systems. A 2-year study was conducted to investigate possible environmental consequences of three tillage systems on a 2.4-ha field located at Macdonald Research Farm, McGill University, Montreal. The soil was a sandy loam (0.5 m depth) underlain by a clay layer. Treatments consisted of a factorial combination of CT, RT, and NT with the presence or absence of crop residue. Soil NO^sub 3^^sup -^-N concentrations tended to be lower in RT than NT and CT tillage treatments. Denitrification and N^sub 2^O emissions were similar among tillage systems. Contrary to the popular assumption that denitrification is limited to the uppermost soil layer (0-0.15 m), large rates of N^sub 2^O production were measured in the subsurface (0.15-0.45 m) soil, suggesting that a significant portion of produced N^sub 2^O may be missed if only soil surface gas flux measurements are made. The N^sub 2^O mole fraction (N^sub 2^O:N^sub 2^O+N^sub 2^) was higher in the drier season of 1999 under CT than in 2000, with the ratio occasionally exceeding 1.0 in some soil layers. Dissolved organic C concentrations remained high in all soil depths sampled, but were not affected by tillage system. [PUBLICATION ABSTRACT]