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Phosphorus deficits by long-term organic farming?

Løes, Anne-Kristin and Ebbesvik, Martha (2017) Phosphorus deficits by long-term organic farming? In: Rahmann, Gerold and Andres, Christian (Eds.) Innovative research for Organic Agriculutre 3.0. Proceeedings of the Scientific Track, Organic World Congress 2017, ISOFAR, TIPI and NCOF (India), pp. 531-534.

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Summary

Long term studies (1989- ) on an organic dairy farm show decreasing topsoil concentrations of extractable phosphorus (P-AL), and a low P surplus on farm level. The average P-AL value, 100 mg kg-1 dry soil is still above optimal (70 mg), but has decreased by more than 50% since 1989. Perennial ley yields tend to decline, and variations in soil P concentrations contribute to explain ley yields. This may call for additional P application on fields with low P status. However, for soils with medium (30-70) or low (< 30) P-AL, no relationship was found with yield level. Further, in a field experiment located on this farm, on low P soil with low and high applications of slurry over 5 years, applied P increased P concentrations in plant material rather than in soil. Future farm management should utilise locally available P sources to close the P gap by bringing back P removed in farm products, to avoid long-term P deficiency in soil.


EPrint Type:Conference paper, poster, etc.
Type of presentation:Paper
Keywords:phosphorus, extractable soil P, nutrient balance
Subjects: Farming Systems > Farm nutrient management
Research affiliation: Norway
Norway > NORSØK - Norwegian Centre for Organic Agriculture
Related Links:https://www.norsok.no/prosjekter/2015/biogassbehandling-av-husdyrgjodsel-hvordan-pavirker-det-jordas-fruktbarhet-feltforsoket-soileffects
Deposited By: Løes, Anne-Kristin
ID Code:32708
Deposited On:28 Feb 2018 16:10
Last Modified:28 Feb 2018 16:10
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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