IMPACT OF DISEASE-SUPPRESSIVE COMPOST ON SOIL QUALITY AND PYTHIUM INOCULUM POTENTIAL

M. Vestberg, S. Kukkonen
The impact of application of two disease suppressing composts, bonemeal and mineral fertilizer on biological, physical and chemical soil quality was studied in a field experiment. The experiment was arranged in a split-split-plot design with three replicate blocks with crop (grass mixture or cucumber) as main plot, number of applications (one, two or three during successive years) as sub-plot and fertilization (mineral, bonemeal, compost 1 and compost 2) as sub-sub-plot. The experiment ran from 2010 to 2012. Inoculum potential of the soil-borne pathogen Pythium (PythiumIP) was determined in a bioassay with cucumber as a test plant. Relative mycorrhizal effectiveness (RME50-value) of indigenous soil arbuscular mycorrhizal fungi was studied in another bioassay with flax as test plant. Both composts decreased PythiumIP significantly as compared with mineral fertilization, the effect being best in compost 2. Application of organic fertilizers had no impact on RME50-values, but these were significantly higher under grass than under cucumber. Compost 2 significantly decreased volume weight of dry soil as compared with mineral fertilizer, but neither compost affected water-holding capacity (WHC). Soil from grass plots had significantly lower volume weight and higher WHC than soil from cucumber plots. The percentage of organic carbon (Corg) in soil was significantly increased by a combined crop and organic fertilizer effect, but organic fertilizer alone did not affect Corg in comparison with mineral fertilizer. Field effects of compost on suppressiveness of Pythium could not be demonstrated, therefore it can be concluded that the use of disease-suppressive compost in the field remains a challenge and will need further research for optimal application of its beneficial effects.
Vestberg, M. and Kukkonen, S. (2014). IMPACT OF DISEASE-SUPPRESSIVE COMPOST ON SOIL QUALITY AND PYTHIUM INOCULUM POTENTIAL. Acta Hortic. 1034, 423-430
DOI: 10.17660/ActaHortic.2014.1034.52
https://doi.org/10.17660/ActaHortic.2014.1034.52
cucumber, grass, soil-borne pathogen, arbuscular mycorrhiza, organic carbon, volume weight, water-holding capacity
English

Acta Horticulturae