No-till only increases N₂O emissions in poorly-aerated soils

• Published in: Soil & tillage research Vol. 101; no. 1-2; pp. 97 - 100
• Main Author: Rochette, Philippe
• Format: Journal Article
• Language: English
• Published: Amsterdam [Amsterdam]: Elsevier Science 01.09.2008; Elsevier
• Subjects: aeration; agricultural soils; Agronomy. Soil science and plant productions; Biological and medical sciences; climatic factors; denitrification; drainage; Fundamental and applied biological sciences. Psychology; gas emissions; greenhouse gases; literature reviews; nitrous oxide; no-tillage; Soil science; soil texture; soil water content; No-till; Gas emission; Zero tillage; N2O; Soil air; Greenhouse gases; Aeration; Drainage; Soils; Drainage class; Greenhouse gas; Soil science; Nitrogen protoxide; Soil aeration
• ISSN: 0167-1987
• DOI: 10.1016/j.still.2008.07.011

Denitrification rates are often greater in no-till than in tilled soils and net soil-surface greenhouse gas emissions could be increased by enhanced soil N₂O emissions following adoption of no-till. The objective of this study was to summarize published experimental results to assess whether the response of soil N₂O fluxes to the adoption of no-till is influenced by soil aeration. A total of 25 field studies presenting direct comparisons between conventional tillage and no-till (approximately 45 site-years of data) were reviewed and grouped according to soil aeration status estimated using drainage class and precipitation during the growing season. The summary showed that no-till generally increased N₂O emissions in poorly-aerated soils but was neutral in soils with good and medium aeration. On average, soil N₂O emissions under no-till were 0.06kgNha⁻¹ lower, 0.12kgNha⁻¹ higher and 2.00kgNha⁻¹ higher than under tilled soils with good, medium and poor aeration, respectively. Our results therefore suggest that the impact of no-till on N₂O emissions is small in well-aerated soils but most often positive in soils where aeration is reduced by conditions or properties restricting drainage. Considering typical soil C gains following adoption of no-till, we conclude that increased N₂O losses may result in a negative greenhouse gas balance for many poorly-drained fine-textured agricultural soils under no-till located in regions with a humid climate.