DOK study compares soil quality of different cropping systems after 42 years of agricultural use

How do different farming systems influence soil quality over time?
The DOK trial (BioDynamic, BioOrganic, Konventionell (German for conventional)) began in 1978 and, having been in operation for over 40 years, is one of the oldest comparative studies of its kind. Most of the test plots receive regular farmyard manure applications in varying amounts. The organically fertilised test plots are compared with both minerally fertilised plots and unfertilised control plots. In their work, the research team led by Hans-Martin Krause investigated how the proportion of soil organic carbon (SOC) has developed over time. The primary research questions were first, how long it takes for changes in SOC content to be detected and, second, which cultivation system is best able to stabilise or build up SOC. The researchers conclude that the application of composted farmyard manure – as is common in biodynamic agriculture – leads to a long-term enrichment of organic carbon in the soil and thus increases soil quality.