Soil nematode communities under the influence of potato cultivation were studied in a laboratory experiment (initial stages of agrocenosis formation) and on the basis of field data (long-term crop cultivation). Natural meadows located nearbyPetrozavodsk(RepublicofKarelia) were considered as controls. Soil nematode community structure in agrocenoses was changed as compared with meadows. The number of bacterial feeders was increased in the short-term observation, the contribution of omnivores and predators as K-strategists to the nematode community, and the abundance of nematodes associated with plants decreased under long-term potato cultivation. In all trials (experimental and field data) values of Maturity index and Structure index decreased. In contrast, the Enrichment index of soil food web increased in field samples. The analysis of nematode metabolic footprints characterizing the magnitudes of carbon flow in the soil food webs is suggested as an effective tool in nematological investigations for assessment of nematode contributions to ecosystem functions of agrocenoses and meadows.