Very important element of proecological vegetables cultivation it is cover plants applied. They have favourable influence on the soil environment, indicated the possibility of limiting mineral fertilizer use and also reduce an application of herbicides, allow to keep soil fertility and in this same achieve high and good quality of yield. An experiment was carried out in 2002–2005 at the Experimental Farm in Zawady belonging to University of Podlasie. The objective of the study was the effect of cover plants (phacelia, spring vetch, serradella and oat) ploughed down in the autumn, spring or retained on the soil surface as a cover crop on the yield of red and savoy cabbage, and dry matter and vitamin C contents in white and savoy cabbage was investigated. The effects of covers were compared to the uncovered control. White cabbage cv. 'Masada F₁', red cabbage cv. 'Koda' and savoy cabbage cv. 'Wirosa F₁' were cultivated. Irrespective of the date of ploughing down of cover plants, serradella was the best plant cover preceding red cabbage, and phacelia was most beneficial when preceded savoy cabbage. Oat cover ploughed down in the autumn favoured dry matter accumulation, when spring-incorporated, stimulated vitamin C in white cabbage. The autumn-incorporated phacelia cover resulted in the greatest dry matter and vitamin C contents in savoy cabbage.

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