Seed yield and weed infestation of pea as well as soil properties were evaluated in the systems of conventional (TA) and conservation (CA) agriculture. In both agricultural systems, pea was grown in crop rotation: potato – winter wheat – pea – winter barley. Shallow ploughing (10–12 cm) after previous crop harvest and pre-winter ploughing (20–25 cm) were performed, whereas a pre-sowing cultivation set was deployed in the springtime in TA. In CA, glyphosate was applied after previous crop harvest, and post-harvest residues were left on the filed surface (4.5 t ha–1). A cultivation-sowing set was used in the springtime, and pea was sown at the beginning of April. The study demonstrated that the agricultural systems tested had no significant effect on pea seed yield. A higher number and air-dry weight of weeds, and a higher weed species number were demonstrated in TA than in CA. Also, a higher number and air-dry weight of weeds were recorded in 2020 than in the other study years. Contents of organic C and total N in the soil and the number of earthworms were higher in CA than in TA.