Introductory lecture. Development of humus researchduring the past Humus et Planta symposia (R. Apfelthaler).Section A Structure, physical and chemical properties ofhumus substances. Application of electron spin resonanceand fluorescence spectroscopies to the study of soil humicsubstances (N. Senesi). Applications of pyrolysis-gaschromatography/mass spectrometry to the study of soils, plantmaterials and humic substances. A critical appraisal (C. Saiz-Jimenez). Section B Relationships among humus soilsproperties and fertility. Carbon and nitrogen dynamics insoil in long term field experiments (M. Körschens). Therole of root properties and organic matter on mobilization ofsoil P and rock phosphates (A. Amberger). Influence of organiccarbon and nitrogen associated with cropping history and soiltextural class on nitrogen use by winter wheat (Triticumaestivum) (L.V. Vaidyanathan, W.S. Wilson). Effect of chemicalproperties of soil on humification of organic soil matter withrespect to organic and mineral phosphorus fractions (L.Kolář, V. Řiha, R. Tichý).Compensation for organic carbon loss from soil at nitrogenfertilizer application (V.N. Kudeyarov). Section CBiotransformations of organic substances in soil. Biotransformations in different climate belts; source - sinkrelationships (H.W. Scharpenseel, H.V. Neue, S.T. Singer).Availability of carbon and nitrogen contained in differentsoil and particle-size fractions (B. Nicolardot, D. Cheneby,M.R. Allard). The fertilizing value of waste waters from theolive processing industry (U. Tomati, E. Galli). Microbialdegradation of plant materials and allelochemicals formationin different soils (W. Weyman-Kaczmarkowa, D. Wójcik-Wojtkowiak). Section D Relationships between humicsubstances and plants. Humic substances affect transportproperties of root membranes (A. Maggioni, Z. Varanini, R.Pinton, M.G. de Biasi). Effect of natural substances onplants: biological control of telluric phytopathogenic fungiby an antifungal compost (O. Reisinger, S. Durecu, F.Toutain). Section E Interactions of humus and xenobioticsubstances. Organic substrates and microbial conversion ofherbicides in soil (F. Kunc). Prediction of the role of soilorganic matter and some other soil characteristics inherbicide adsorption (J. Kozák, M. Valla, P. Prokopec,O. Vacek). Surveys of individual poster sessions. Humicsubstances, their structure, chemical and physical properties(M. Valla). Relationships between humus, soil properties andsoil fertility (L. Kolář). Biotransformations oforganic matter and nitrogen in soil (J.Nováková, M. Tesařová).Relationships between humus substances and plants (F.Pospišil). Interactions of humus and xenobioticcompounds (F. Kunc).