Low nitrous oxide emission from organic management results in efficient production

• We compare nitrous oxide (N2O) emission due to organic and integrated conventional farming systems on a research farm "Logården" in south-west Sweden. The soil is characterized by an average clay content of 40%. Both systems have 7 year crop rotations since 1991. Faba beans and spring wheat crops in each management system are compared. The faba bean crops did not receive any nitrogen addition. The organic fields were weeded by hoe while the integrated fields had an under-sown catch crop. Spring wheat followed the next year after the beans, where both managements had a green manure crop under-sown. Fertiliser is only given to the conventional field, 110 kg N ha-1. N2O emission rate was measured by manual chambers during two years. Gas samples were collected every second week and more frequent during freeze/thaw events and at management occasions. Integrated beans had significantly higher emissions (2.3 kg N2O-N ha-1) than the organic. The organic wheat had the significantly lowest average N2O emission (0.2 kg N2O-N ha-1) one year out of two The overall emission is governed by very few occasions of high emissions, mainly in spring and autumn but not specifically following fertiliser addition. We try to explain the causal factors. Yield-scaled N2O emission (emitted N2O-N per harvested N) was found low for both management systems producing wheat but only for the organic faba beans, all having ca 10 g N2O-N kg-1 harvested N, which was twice as high for the integrated beans. Based on our results we discuss options for sustainable and productive agricultural management characterised by low emissions.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries (hsv//eng)

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

Faba beans; Integrated farming; Clay soil

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