Changes in the nutrient content of agricultural soil on conversion to organic farming in relation to farm-level nutrient balances and soil contents of clay and organic matter

• Published in: Acta agriculturae Scandinavica. Section B, Soil and plant science Vol. 47; no. 4; pp. 201 - 214
• Main Authors: Loees, A.-K. (Norwegian Centre for Ecological Agriculture, Tingvoll (Norway)), Oegaard, A.F
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 01.12.1997
• Subjects: AGRICULTURA ORGANICA; AGRICULTURAL SOILS; AGRICULTURE BIOLOGIQUE; AZOTE; CALCIO; CALCIUM; carbon; ECOLOGIA; ecological; ECOLOGIE; ECOLOGY; FOSFORO; MAGNESIO; MAGNESIUM; NITROGEN; NITROGENO; NORUEGA; NORVEGE; NORWAY; NUTRIENTES; NUTRIENTS; ORGANIC AGRICULTURE; PHOSPHORE; PHOSPHORUS; POTASIO; POTASSIUM; PROPIEDADES FISICO-QUIMICAS SUELO; PROPRIETE PHYSICOCHIMIQUE DU SOL; SOIL CHEMICOPHYSICAL PROPERTIES; SOL AGRICOLE; SUBSTANCE NUTRITIVE; SUELOS AGRICOLAS; sustainable agriculture; whole farm case studies
• ISSN: 0906-4710; 1651-1913
• DOI: 10.1080/09064719709362462

Agricultural soil on 12 farms converting to organic farming was sampled in 1989 and 1995 at the same sample points. Concentrations of plant-available (-AL) P, K, Ca and Mg, HNO 3 -soluble K, total-N, total-C and pH were measured in two layers. The average K-AL concentration and pH were reduced in both layers. The average P-AL concentration was reduced in the topsoil. K-AL and P-AL increased in samples with low concentrations and decreased in samples with high and very high concentrations in 1989. K HNO3 increased in the topsoil and total-N increased in the subsoil. Total-N and total-C increased in top- and subsoil with a low organic matter content. The net import of P, calculated by farm-level nutrient balances, was negatively correlated to the change in kg P-AL ha −1 in the topsoil. No such correlation was found for K.