The soil from a field experiment was determined for: (1) earthworm (Lumbricus) number, (2) organic carbon content, (3) total nitrogen content, (4) available phosphorus content, (5) potassium content, and (6) magnesium content depending on tillage systems and previous crops cultivated. The two-factor experiment was established in the system of randomized subblocks. Tillage systems (TS): conventional tillage (CT), reduced tillage (RT), and no-tillage (NT) were the main experimental factor; whereas previous crops (CP): winter wheat, winter durum wheat, winter barley, and common pea were the second-order experimental factor. Shallow ploughing and pre-sowing ploughing were performed in the CT system, double cultivation in the RT system, and only glyphosate treatment in the NT system. An over 2-fold higher number of earthworms per m2 was recorded on RT and NT plots than on the CT plots as well as on plots after winter barley and pea than on these after winter wheat and winter durum wheat. The contents of organic C and total N were higher in NT and RT systems compared to the CT system, and also on plots after pea than on these after all other analyzed crops. The content of P was higher in the soil from the RT plot than in the soil samples from CT and NT plots as well as in the soil from the plots after winter wheat than in that from plots after durum wheat, pea, and winter barley. Also, higher K and Mg contents were determined in the soil from the RT system compared to CT and NT soil samples, as well as in the soil from the plots after durum wheat than after pea, winter wheat, and winter barley.