This groups divides the agricultural trials into groups with regard for targets, distinguishes the trials with varieties which results should be confirmed in agricultural practice and the seed trials which results should be used in the seed production. In these trial groups the author recommends using methods and machines tor harvest which give the results similar to the results which are achieved in the agricultural practice or in the seed production. In the scientific trials the author recommends using the methods and the machines which make possible achivement and collecting of maximum yield. It will give possibility of estimation of yield potential of tested genotype. In special trials (field cultivation, fertilization) the should be taken into consideration expediency of achievement of result which make possible elaboration of suitable recommendation for farmers. In order to obtain the precise results for all the trial groups it is necessary to use modern and precise machines for field cultivation, fertilization, sowing and plant protection.