They are carried out two comparative experiments for determining the real guiding accuracy of a seed drill during spring sowing an earth-up crop. At the first one the seed drill is running with circle turns. The juxtaposition is made for the guiding accuracy by conventional disk markers and by agricultural navigation with RTK correction. At the second experiment the seed drill is running with stretch turns. The guiding accuracy of both navigation without RTK and RTK navigation are compared. The agricultural navigation with RTK ensures better statistical estimations, better qualitative indices for the boundary row distance and higher operational indices of the tractor with a seed-drill during sowing of the earth-up crop.