abstract: The aim of the present research was to compare the residual effect of four nurse-crops cultivated on a light soil on the yielding of six companion crops. The field experiment was carried out in the years 1993-1997 at the Experimental Station of Bezek near Chełm. The static field research was carried out by the split-plot method in four replications. The field experiment included six companion crops: serradella Bydgoska 40 kg ha-1, white clover Podkowa 10 kg ha-1, red clover Hruszowska 20 kg ha-1, hop trefoil Renata 15 kg ha-1, white melilot Selgo 20 kg ha-1, Dutch ryegrass Motycki 40 kg ha-1 planted into four cereal crops: winter rye Dankowskie Złote (240 plants per m-2), winter triticale Presto (350 plants per m-2), spring barley Rudzik (230 plants per m-2) and oat Dragon (400 plants per m-2), and a control treatment. The root mass was determined after harvest by means of a steel cylinder of 400 cm-2 down to 25 cm. The roots were rinsed with running water on a sieve with mesh of about 1 mm, then they were dried and weighed. Dutch ryegrass produced the biggest air dry mass of roots compared to the remaining companion crops. The nurse-crops did not differentiate the air dry mass of roots of companion crops which, however, displayed a significant dependence on climatic conditions.