A field experiment was established in 2003-2005 at Uhrusk Experimental Station of Lublin Agricultural University. The experiment was conducted according to the method of split–plot which was designed with four replications, on 10 m2 plots. The grey-brown rendzina soil was formed from light loam, weak sandy, and it was classified into the very good rye complex. The experiment concerned five forecrops for hard wheat: pea, potato, hard wheat (1x), hard wheat (2x), hard wheat (3x), and two agrotechnical levels: minimized (nitrogen 90 kg ha–1, harrowing) and intensive (nitrogen 140 kg ha–1, harrowing, herbicides: 2,4-D, fenoxaprop-P-ethyl and fungicides). Number of weeds in hard wheat was higher after hard wheat (3x) in relation to pea, potato, wheat (1x) and wheat (2x). Air dry mass of weeds in hard wheat was higher after hard wheat (3x) and hard wheat (2x) in relation to pea, potato, and wheat (1x). Intensive agrotechnical level decreased the number and air dry mass of weeds, in relation to the minimized level. In hard wheat predominated: Avena fatua, Chenopodium album, Amaranthus retroflexus, Stellaria media, Fallopia convolvulus, Galium aparine, Veronica persica and Melandrium album.