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Nitrous oxide emissions from organic farming: the importance of well-timed ley cultivation

Ball, B C (2006) Nitrous oxide emissions from organic farming: the importance of well-timed ley cultivation. In: Atkinson, C; Ball, B; Davies, D H K; Rees, R; Russell, G; Stockdale, E A; Watson, C A; Walker, R and Younie, D (Eds.) Aspects of Applied Biology 79, What will organic farming deliver? COR 2006, Association of Applied Biologists, pp. 317-320.

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Summary

The period after ploughing of grass-clover within a ley-arable rotation is when nitrogen accumulated during ley cropping is most vulnerable to loss. I investigated how date of ploughing and date of cessation of grazing before ploughing influenced losses of nitrogen as nitrous oxide during establishment of the first cereal crop. Crop nitrogen uptake was also assessed. Nitrous oxide (N2O) emissions in the 1-2 month period after autumn or spring ploughing or after sowing were typically between 20 and 150 g N ha-1 day-1 and increased with temperature and rainfall. Tillage and sowing operations on previously ploughed soil stimulated N2O emissions even several months after ploughing. Cumulative N2O emissions were highest (~8 kg ha-1 over 17 months) after late cessation of grazing and late ploughing, and lowest (~5.5 kg ha-1) after early cessation of grazing and early ploughing. The optimum time of ploughing appears to be midwinter when the cold restricts nitrogen mineralisation, but sufficient nitrogen subsequently becomes available for early spring crop growth and satisfactory N offtake. Restricting tillage operations to cool conditions should help to reduce N2O emissions. However, the soil should also be dry enough to reduce the risk of damage to soil structure.


EPrint Type:Conference paper, poster, etc.
Type of presentation:Poster
Keywords:Greenhouse gas, ley-arable, nitrogen offtake, ploughing and grazing
Subjects: Soil > Nutrient turnover
Crop husbandry > Crop combinations and interactions
Crop husbandry > Soil tillage
Research affiliation: UK > Scottish Agricultural College (SAC)
UK > Colloquium of Organic Researchers (COR) > COR 2006
Deposited By: MILLMAN, Mrs Carol A
ID Code:10261
Deposited On:20 Dec 2006
Last Modified:12 Apr 2010 07:34
Document Language:English
Status:Published
Refereed:Not peer-reviewed

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