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Can organic farming help to reduce N-losses? (1998)

Dalgaard, Tommy ; Halberg, Niels ; Sillebak Kristensen, Ib

Springer

Nutrient cycling in agroecosystems 52 (1998), S. 277-287

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ISSN: 1573-0867

Keywords: dairy farming ; efficiency ; nitrogen ; organic ; pig farming ; surplus

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract This study is in two parts. In the first part, nitrogen (N) losses per unit of milk and meat in Danish conventional and organic pig and dairy farming were compared on the basis of farm data. In the second part, organic and conventional dairy farming were compared in detail, using modelling. N-surpluses at different livestock densities, fodder intensities, and soil types were simulated. Finally, simulated N-surpluses were used in national scenarios for conversion to organic dairy farming in Denmark. In Part one, pig farming was found to have a higher N-efficiency than dairy farming. Organic pig production had a lower N-efficiency and a higher N-surplus per kg meat than conventional pig production. The possibilities to reduce N-loss by conversion to organic pig production therefore appear to be poor. Organic dairy farming had a higher N-efficiency and a lower N-surplus per kg milk than conventional dairy farming. Conversion from conventional to organic dairy farming may therefore reduce N-losses. In Part two, a positive correlation between livestock density and N-surplus ha-1 was found for dairy farming. For all simulated livestock densities, fodder feeding intensities and soil types, organic systems showed a lower N-surplus per unit of milk produced than conventional systems. National scenarios for dairy farming showed that the present Danish milk production could be achieved with a 24% lower total N-surplus if converted from intensive conventional farming to extensive organic farming. At the same time, N-surplus ha-1 and N-surplus (t milk)-1 would be lowered by 50% and 25% respectively. Changing from intensive to extensive conventional dairy farming with a livestock density equal to that in the organic scenario resulted in a reduction in N-surplus ha-1 of 15%. It was concluded that a reduction in total N-loss from agriculture is possible by converting from conventional to organic dairy farming but at the cost of either lower production on the present dairy farm area, or the current production on a substantially larger area.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009790722044

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Estimated N leaching losses for organic and conventional farming in Denmark (2006)

TRYDEMAN KNUDSEN, MARIE ; SILLEBAK KRISTENSEN, IB ; BERNTSEN, JØRGEN ; [et al.]

Cambridge University Press

In: Journal of Agricultural Science. 2006; 144(2): 135-149. Published 2006 Feb 10. doi: 10.1017/s0021859605005812.

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Publication Date: 2006-02-10

Description: The impact of organic, compared with conventional, farming practices on N leaching loss was studied for Danish mixed dairy and arable farms using an N balance approach based on representative data. On mixed dairy farms, a simple N balance method was used to estimate N surplus and N leaching loss. On arable farms, the simple N balance method was unreliable due to changes in the soil N pool. Consequently, the Farm ASSEssment Tool (FASSET) simulation model was used to estimate N surplus, N leaching loss and the changes in the soil N pool.The study found a lower N leaching loss from organic than conventional mixed dairy farms, primarily due to lower N inputs. On organic arable farms, the soil N pool increased over time but the N leaching loss was comparable with conventional arable farms. The soil N pool was increased primarily by organic farming practices and incorporation of straw. The highest increase in the soil N pool was seen on soils with a low initial level of organic matter. The N leaching loss was dependent on soil type, the use of catch crops and the level of soil organic matter, whereas incorporation of straw had a minor effect. N leaching was highest on sandy soils with a high level of soil organic matter and no catch crops. The present results stress the importance of using representative data from organic and conventional farming practices in comparative studies of N leaching loss. Lack of representative data has been a major weakness of previous comparisons on N leaching losses on organic and conventional farms.

Print ISSN: 0021-8596

Electronic ISSN: 1469-5146

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition