About 15% of the world surface suffers the effect of man activities. The main causes of surface degradation are livestock production, desertification and excess of cultural mechanic practices in Mexico little attention have been done to soil conservation as a removable resource. The soil degradation has been increased as a result of excess of agricultural machinery uses, consequently 64% of national soil surface is affected. The Comarca Lagunera located between Coahuila and Durango states is main milk cow production region. Therefore, annually in this region 900 0000 t of cow manure is produced. This amount of cow manure must be used again in soil fertility and biology studies. The main objective of this study was to determine the effect of conservation tillage and cow manure amounts and their effects over soil physics properties and corn forage production. In the spring crop cycle of 2003 were evaluated two tillage systems; conventional and conservation and four fertilizer levels; 40, 60 y 80 kg ha-1 of cow manure and one with chemical fertilizer. The experimental design used was randomized block, with four replications. The results show statistical differences in soil physical properties measured. With respect corn forage yields the conventional tillage systems had a 16% higher than conservation tillage system. Key words: Tillage conservation, agricultural practices, cow manure.