Organische Substanz in ökologisch bewirtschafteten Böden,Quantität, Qualität und ihr Einfluss auf Getreideerträge

In an on-farm investigation a total of 39 fields of 9 organic managed farms (main crop winter cereals) were sampled in the years 2005 and 2006. Several soil variables were evaluated as well as crop yield, weather data and the field history. Results of statistical analyses (mean, range, standard deviation, correlation and multiple linear regression) are presented. Comparable to physical and chemical variables certain fields were also characterised by soil biological variables. Main factors of cereal N-yield were pre crop, crop rotation, soil type and soil organic matter content (SOM). Soil biological variables had only a low influence. Nitrogen availability was affected by physical and biological soil factors, the weather and management measures as straw fertilization and pre crop. Negative correlations between SOM and yield or N-availability were probably caused by the connection of SOM and environmental factors