In a view of the predicted drought that has appeared in recent years and water shortage in the growing season, which is getting worse every year, the problem of water retention in the soil and increasing its humidity becomes of exceptional importance. The field experiment was carried out in 2009–2012 on grey brown podzolic soil developed from loess formations covering the cretaceous marls with a granulometric composition corresponding to medium dusty loam. The aim of the study was to assess the impact of various species of cover crops and the method and date of mixing their biomass with the soil on the soil moisture in ploughless carrot cultivation. The experimental design included seven cover crop species (spring rye, common oat, common vetch, white mustard, lacy phacelia, buckwheat, fodder sunflower) and six kinds of soil tillage. The effect of cover crops and tillage on soil moisture was modified by the course of the weather and varied depending on the year of research, sampling date and soil layer. In spring, the highest layer of soil (0–20 cm) not cultivated before winter (NTz) accumulated the most water, and the least after pre-winter ploughing (Oz). In the 0–40 cm layer, the lowest humidity was in the soil ploughed before winter (Oz), and the highest after no-till (NTz) and after subsoiling before winter (GLz). The ridge cultivation performed in the spring caused the soil to dry out. In the remaining variants of no-ploughing tillage, soil moisture in the 0–40 cm layer was similar to that of conventional cultivation. Cover crops exerted a significant influence on the soil moisture in carrot cultivation at all test dates, increasing its moisture content compared to cultivation without cover crops. The rye cover crop had particularly favourable effect on the soil moisture.