Einfluss von biologischer und konventioneller Bewirtschaftung auf biologische Bodenqualitätsparameter: Entwicklungen im DOK Langzeitversuch nach pH-Regulierung

Summary

In the long-term DOK field trial at Therwil, Switzerland, agricultural farming systems
are compared since 1978: CONFYM (mineral and organic fertilisers, synthetic
pesticides), BIOORG (organic fertilisers, mechanical weeding and biological disease
and pest control) and BIODYN (with composted manure and bio-dynamic
preparations), all of them at two fertiliser intensities of 0.7 and 1.4 livestock units per
ha, respectively. They are compared with CONMIN (conventionally managed,
exclusively minerally fertilised) and NOFERT (unfertilised control). CONFYM and
CONMIN were limed with 2.7 t CaCO3 ha-1 in 1999, CONMIN with additional 2 t
CaCO3 ha-1 in 2005, since pH values had dropped below officially recommended
values. In spring of 1998 and 2006 soil samples from 0 to 20 cm depth were analysed
for soil microbial biomass (substrate induced respiration SIR and chloroform
fumigation extraction CFE), soil respiration and dehydrogenase activity.
NOFERT and CONMIN exhibited the lowest microbial soil properties Manure
application influenced most soil microbial parameters positively. Differences between
treatments in soil microbial parameters were smaller in 2006 than in 1998 due to pH
regulation. Only CFE and dehydrogenase activity were higher in BIODYN than in
BIOORG and CONFYM in 2006. For physiological methods SIR and soil respiration,
no differences between these three systems were measured. Because of liming,
manure use, a wide ley rotation and equal plant residue management no more
differences between BIOORG and CONFYM, representing the predominant farming
systems in Switzerland were observed for all soil microbial properties.