Auswirkungen differenzierter Bodenbearbeitung auf das Bodengefüge und die Stickstoffdynamik von Lößböden bei viehloser und viehstarker Bewirtschaftung

Abstract

Abstract Effect of different tillage practices on soil structure and nitrogen dynamic in loess soils with and without longterm application of farmyard manure Field trials were conducted in 1979 and 1980 on two farms with and without longterm application of farmyard manure respectively, to study the effect of different tillage practices (ploughing at low soil moisture in summer and autumn and ploughing at highsoil moisture in autumn) on soil structure and nitrogen dynamic. Soil structure measurements showed great differences between ploughing at low and high soil moisture contents. Ploughing soil at high moisture contents caused a rise in penetrometer resistance as in bulk density and a decrease of macropors as well as in oxygen concentration in top soil and in tillage pan. But little differences were observed between ploughing in summer and autumn at low soil moisture contents.Ploughing soil at high moisture contents caused a higher soil compaction on the farm without longterm application of farmyard manure compared to the farm with longterm application of farmyard manure.The differences in soil nitrate content were strongly correlated with soil compaction. Very large differences in soil nitrate content between ploughing at low and high soil moisture contents were always observed in May, when the soil temperature was higher than 15°C These differences in soil nitrate content are due to reduced nitrogen mineralization and an increase of denitrification activity after ploughing at high soil moisture contents.