Global Maize Project in Mexico: Toluca, México

IPNI-2010-MEX-GM29

08 Apr 2011

2010 Annual Interpretive Summary


México’s central highlands include highly productive agricultural valleys ranging in altitude between 2,000 and 2,800 meters above sea level (masl). The diversity of environments and farming systems pose varied challenges related to crop nutrition.

The study was started in 2009 in Toluca, México State, at an altitude of 2,370 masl 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 other half of the treatments were similar to current farmer practices with regards to plant population and fertilizer application (30 kg P2O5/ha and 30 kg K2O/ha). Three fertilizer N application regimes were combined with the management systems just described: no N, 300 kg N/ha applied 2 out of 3 years, and 300 kg N/ha applied every year with the intensive management, and no N, 180 kg N/ha applied 2 out of 3 years, and 180 kg N/ha applied every year, with the farmer management.

In 2010, plant population at harvest in the intensive management treatments (83,750 plants/ha) was 30% higher than in the farmer management (64,635 plants/ha).The intensive management system with 300 kg N/ha applied both in 2009 and 2010 produced the highest grain yield (10.3 t/ha). Grain yield without applied N–under both management systems—averaged 4.7 t/ha, which is 46% of the maximum. High yields were associated mainly with large ears and number of grain/m2. Under both population densities, no N application resulted in almost 30% less ears/ha. High plant populations were associated with lower grain harvest index values; the lowest grain harvest index corresponded to the high plant population and no N applied.

Under intensive management, the agronomic efficiency (AE) of N was 19 and 14 kg grain/kg N when N was applied in 2009 and 2010 and only in 2010, respectively. Both values are low. The application of N in 2009 affected the response to N in 2010 when the intensive management was used, but not under the farmer management. No significant effect of N management on ear size could be detected under the farmer plant populations. However, the heaviest grains were observed when N was applied under the farmer management. IPNI-29