Grass-clover leys are an integral part of organic rotations. We performed an
experiment with reduced tillage (RT) and conventional tillage (CT) using mouldboard
ploughing in a rotation in Frick (Switzerland) on a heavy soil and 1000 mm mean
annual precipitation. The grass-clover mixture was sawn in autumn 2005 after uniform
seed bed preparation with a rotary hoe in both tillage systems without ploughing. After
emergence most of the clover seedlings collapsed in the CT plots due to draught,
while they survived in the RT plots. This led to a much higher share of clover in the
mixture under RT. Grass-clover yields were 29 and 23% higher in RT than in CT plots
in the first and second year of cultivation in 2006 and 2007, respectively. Grass grown
in RT plots was higher in nitrogen (N), phosphorous (P), potassium (K) and
magnesium (Mg) content than in CT plots; clover contained solely more P in RT plots.
Over all grass-clover had better growing conditions in RT compared to CT plots in our
experiment, reflecting after-effects of the differentiated tillage schemes applied for the
preceding arable crops. It is suggested that reduced tillage has a high potential to
improve water stress tolerance of cropping systems
