The present work was developed between January · and October of the 2000, in the object of evaluating the effect of fann zero in yield of 4 varieties of commercial of rice one cari-ies out an experimend Found 2ª of the UNSM located in the District of Cacatachi, county and Department of San Martin, located geographically at 06º 22 of south latitude, 76.12 longitude west, with an altitude of 330 m.s.n.m., you uses the statistical design of (DBCR) with 04 treatments and 04 repetitions. The system of farm zero consists on carrying out the following activities: To give a heavy watering to facilitate the germination of rice remainder and overgrowths, to eliminate the overgrowths then with glifosato, to carry out another watering before the 1 volley of the seed. Certified seed was used and it was volleyed pre-germinated to reason of 80 Kg. /Ha., in each variety parcels of 50 m2 were used in ...