DOK-Versuch (Langzeituntersuchung zu biologisch-dynamischen, organisch-biologischen und konventionellen Landbausystemen)An understanding of agro-ecosystems is key to determining effective farming systems. Here we report the 21-year study of agronomic and ecological performance of bio-dynamic, bio-organic, and conventional farming systems in Central Europe. We found crop yields to be 20 % lower in the organic systems, although input of fertiliser and energy was reduced by 34 – 53 % and pesticide input by 97 %. Enhanced soil fertility and higher biodiversity found in organic plots may render these systems less dependent on external inputs. Definition of the problem: Soils are well buffered systems and an adaptation of the soil - plant relationship from high-input to low external input farming practices may last decades. For instance, soil nutrient stocks are frequently huge in European soils and a normalisation after conversion to organic low-input systems needs time. Also the adaptation of the soil micro-flora to altered chemical soil conditions presumably occurs only after a prolonged period of time upon conversion from high-input to low-input farming. Therefore, long-term trials are essential to assess the agronomic performance of low-input production systems and a focus should be put on studying the underlying soil processes. Project aims: - to analyse the long-term agronomic performance of a Swiss wheat cultivar under organic and integrated farming systems (continued) - to investigate the interrelations of soil properties and plant growth in different farming systems Experiments: - to perform a system comparison experiment with organic and integrated farming (continued, running since 1978) - to assess soil chemical, physical and biological properties - to determine nitrogen and phosphorus dynamics related processes in the soil-plant –microorganisms - system - to study the soil - plant interface Methodology: Soil microbial biomass analyses, enzyme activities, characterisation of microbial populations (Biolog, PLFA, DNA), assessment of mycorrihizal root colonisation and diversity by molecular tools, isotope tracer and dilution techniques. Soil Biodiversity and ecosystem servicesProject description