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Phosphorus budget and phosphorus availability in soils under organic and conventional farming

Oehl, F.; Oberson, A.; Tagmann, H.U.; Besson, J.M.; Dubois, D.; Mäder, P.; Roth, H.-R. and Frossard, E. (2002) Phosphorus budget and phosphorus availability in soils under organic and conventional farming. Nutrient Cycling in Agroecosystems, 62, pp. 25-35.

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Summary in the original language of the document

The aim of this work was to assess to which extent organic farming practices would affect the accumulation of total and available phosphorus (P) in a cropped soil in comparison to conventional practices. In order to achieve this, soil samples were taken from a long-term field trial comparing a non-fertilised control (NON), two conventionally cultivated treatments (MIN, CON), and two organically cultivated treatments (ORG, DYN). Soil samples were taken from each treatment at two depths (0-20 and 30-50 cm) before starting the field trial (1977) and at the end of every three crop rotations (1984, 1991 and 1998). They were then analysed for total P (Pt ), total inorganic P (Pi ), total organic P (Po) and isotopically exchangeable Pi . After 21 years, the average P input-output budget reached -20.9 kg P ha−1 a−1 for NON, -7.8 for DYN, -5.7 for ORG, -5.0 for MIN and +3.8 for CON. Total P, Pi as well as the amount of Pi isotopically exchangeable within 1 minute (E1) were positively correlated to the P budget. Comparison between P budget and Pt in the top- and subsoils of the fertilised treatments suggested a net transfer of P from the 0–20 to the 30–50 cm layers between 13 and 26 kg P ha−1 a−1during the first rotation and between 3 and 12 kg P ha−1 a−1during the second rotation. During the third rotation a net upward movement of P from the subsurface to the topsoil ranging between 3.7 and 10.5 kg P ha−1 a−1was estimated. In the topsoil, E1decreased from an initial value of 12 mg P kg−1 to 11 in CON, 8 in MIN, 6 in ORG, 5 in DYN and 2 in NON after 21 years. In the subsoil, E1 increased from an initial value of 2 mg P kg−1 to 4 in MIN, ORG, DYN and NON and to 6 in CON. These results show that, with the exception of NON, all treatments had still an adequate level of available P after 21 years of trial and that, in this low to moderately P sorbing soil, an equilibrated input-output budget allows to maintain P availability at a constant level. In the organic systems, yields have so far partly been attained at the expense of soil reserves or residual P from earlier fertiliser applications.


EPrint Type:Journal paper
Keywords:conventional farming, integrated production, organic farming, P availability, P budget, P loss, P movement, Department of Soil Sciences, Long-term Experiments, DOK-Trial, Systems comparison
Agrovoc keywords:
Language
Value
URI
English
conventional farming
UNSPECIFIED
English
integrated production
UNSPECIFIED
English
organic farming
UNSPECIFIED
English
P availability
UNSPECIFIED
English
P budget
UNSPECIFIED
English
P loss
UNSPECIFIED
English
P movement
UNSPECIFIED
Subjects: Soil
Research affiliation: Switzerland > ETHZ - Agrarwissenschaften
Switzerland > FiBL - Research Institute of Organic Agriculture Switzerland > Crops > Field trials > DOK Trial
Switzerland > FiBL - Research Institute of Organic Agriculture Switzerland > Soil
Switzerland > FiBL - Research Institute of Organic Agriculture Switzerland > Sustainability > Climate
Switzerland > Other organizations Switzerland
Deposited By: Mäder, Paul
ID Code:26761
Deposited On:26 Sep 2014 11:36
Last Modified:19 May 2021 12:07
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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