Abstract
The aim of the study was to compare the grain yield and weed infestation rate of winter wheat in crop rotations with 40, 60 and 80% share of cereals and in continuous cropping. The trial was situated in the area of continental climate. The trial had two parts. In the first part, there were crop rotations with 40, 60 and 80% share of the cereals. Two levels of fertilization were used: H1 mineral fertilization + organic manure Veget; H2 mineral fertilization only. In the second part, winter wheat and spring barley were grown in monoculture. Three variants of fertilization were used: 1 - mineral fertilization; 2 - mineral fertilization + straw of cereals were ploughed; 3 - mineral fertilization + straw of cereals + organic manure Veget were ploughed in the soil. In the years 2006-2009 the grain yield, thousand kernel weight and weed infestation rate of winter wheat in different crop rotations and by the continuous cropping were investigated. The statistically higher winter wheat grain yield (6.50 t ha-1) was recorded by 40% share of cereals in crop rotation than by 60% and 80% share of cereals (6.23 t ha-1). The grain yield of winter wheat by continuous cropping was lower by 2.24 t ha-1 (34.46%) than in crop rotation with 40% share of cereals. The weed infestation rate by 80% share of cereals in crop rotation was determined 2.4 times higher than by 40% share of cereals.