Global Maize Project in Mexico: Toluca, México

The study was started in 2009 in Toluca, State of México, at an altitude of 2,370 meters above sea level. The objective was to compare the effects of six combinations of plant populations and fertilizer applications. Half of the treatments—labeled as intensive management—included high plant populations and the application of a complete fertilizer formula (90 kg P₂O₅/ha, 90 kg K₂O/ha, 44 kg MgO/ha, 50 kg S/ha, and 3 kg Zn/ha). The remaining treatments were similar to current farmers’ practices with regards to plant population and fertilizer application (30 kg P₂O₅/ha and 30 kg K₂O/ha). Three N fertilizer application regimes were combined with the management systems just described: 0-N, 300 kg N/ha applied two out of three years, and 300 kg N/ha applied every year with the intensive management, and 0-N, 180 kg N/ha applied two out of three years, and 180 kg N/ha applied every year, with the farmers’ management.

The 2011 season was very bad, with lack of rain at the beginning; followed by flooding, hail storms, and a devastating early frost in the first week of September. The yield levels were therefore lower than in the previous years. Yield under intensive management (3,594 kg/ha) was significantly higher than under traditional management (2,699 kg/ha). This result mirrored the differences in plant population at harvest: 80,208 and 62,691 plants/ha in the intensive and farmers’ management treatments, respectively. Under intensive management, yields with N (3,906 kg/ha) were 31% higher than without N (2,971 kg/ha), whereas no significant effects from N could be detected under the traditional management. Partial Factor Productivity was low under both management systems: 12 and 15 kg grain kg/N, for intensive and traditional, respectively. Likewise, agronomic efficiency was extremely low (3 kg grain/kg N for both management systems). IPNI-29