IN ORGANIC CROP ROTATION WINTER COVER CROPS IMPROVE SOIL, WEED SUPPRESSION AND CROP YIELDS

The aim of this study was to investigate the effects of different winter cover crops (CC) in combination with composted cattle manure on weed infestation, crop yields and soil characteristics. The experiment was conducted in 2012-2014 in three different organic cropping systems under five-field crop rotation (barley undersown with red clover, red clover, winter wheat, peas and potato). The control system followed the given rotation, whilst in the second and third organic system also winter cover crops (ryegrass after winter wheat (in 2012) and mixture of winter oilseed-rape and winter rye (since 2013); winter oilseed rape after pea and winter rye after potato) were used. In the third organic system composted cattle manure in addition to winter cover crops was applied The results indicate, that winter cover crops reduced the dry biomass and density of weeds compared to the control system. In 2012 and 2013 the best suppressor of weeds was winter lye, in 2014 the mixture of winter rye and oilseed rape. In 2012 and 2013 there was a statistically significant increase of barley and potato yields under the combination of green manure with cattle manure. These results also indicate a remarkable improvement of soil properties, such as the decrease of soil acidity and increase of Carbon (C) content.