Importance of the soil in the Burgrain farmingsystem trial

In the Burgrain field trial (1991–2008; Alberswil, Canton of Lucerne, Switzerland), where the soils have developed on alluvial and moraine sediments, it was found that the soil nature often had greater effects on the investigated parameters than the three different farming systems applied, which were «intensive IP» (Integrated Production) with intensive use of auxiliary substances, «extensive IP» with restricted use of auxiliary substances, and «organic». The alluvial Calcari-gleyic Cambisol plots with 4 % humus and 22 % clay content showed a more stable soil structure and a significantly higher nitrogen mineralisation potential than the decarbonated Cambisol plot on moraine with 2,6 % humus and 17 % clay. Because of this, the organic wheat grown on the moraine plot, fertilized with only small amounts of nitrogen, achieved no more than barely sufficient protein contents in some cases. In contrast, the high amounts of soil-borne nitrogen in the more humous gleyic soils occasionally led to lodging in the case of the extensively raised «Extenso» cereals. The biomass of earthworms and soil microorganisms was significantly higher in the alluvial than in the moraine soils. Because of the similar tillage methods and the use of farmyard manures in all three systems, there was little evidence for differences in soil biological parameters between the farming systems. Only reduced tillage in «extensive IP» towards the end of the trial provided generally positive results on these parameters.