Accumulative Effect of Long-term Conservation Tillage Methods on Irrigated Corn in San Luis Potosi, Mexico.
Miguel A. Martinez-Gamiņo and Cesario Jasso-Chaverria. INIFAP, Santos Degollado #1015, Col.Cuauhtemoc, San Luis Potosi, Mexico
Conservation tillage has not been successfully adopted by farmers in the north central region of Mexico as in other Latin American Countries because of the use of crop residues to feed animals. As an alternative to this problem, a long-term conservation tillage experiment with an irrigated corn-forage oat rotation was established with the following objectives: to assess the accumulative effect of seven tillage methods on corn grain and stubble yields so farmers can leave at least 2 ton ha-1 of corn stubble as soil cover. Conservation tillage methods were established since the spring of 1995 and traditional tillage were performed twice a year, one before sowing corn and the other before planting oat. Corn was growth during the spring-summer season and forage oat for the fall-winter period of each year. Seven tillage methods have been evaluated: 1) traditional with plow and disk (B+R), 2) disturbing the upper 0-10 cm layer (R), 3) without disturbing the upper 0-10 cm layer (M), 4) zero tillage with 0% soil covered by crop residues (ZT-0%C), 5) zero tillage with 33% soil covered by crop residues (ZT-33%C), 6) zero tillage with 66% soil covered by crop residues (ZT-66%C), and 7)zero tillage with 100%% soil covered by crop residues (ZT-100%C). Since the first year, corn grain yield obtained with all ZT treatments was statistically higher (p ≤ 0.05) than that of B+R, and it was consistent throughout each one of the 10-year period evaluated so far. Corn grain 10-year average yield was increased 60% compared to that of B+R. In addition, with the same treatments, corn stubble yield was increased 3.431 ton ha-1, indicating that farmers can use 2 ton ha-1 to cover at least 33% of the soil surface. It could be concluded that zero tillage in a corn-forage oat rotation system is a good option to increase corn grain and stubble production with a sustainable trend in the north-central region of Mexico.