Global Maize Project in Mexico: Celaya, Guanajuato

The study was started in 2009 in Celaya, State of Guanajuato, Mexico, at 1,830 meters above sea level. The treatment design included a combination of two management systems (plant populations) (Farmers’ practice [FP] and a higher population [EI]) and three N fertilization regimes (0-N, 300 kg N/ha applied two out of three years, and 300 kg N/ha applied every year). In 2011, the six treatments were: 1) 120,192 seeds/ha, 0-N; 2) 120,192 seeds/ha, 300 kg N/ha (0 N in 2009; 300 kg N/ha in 2010); 3) 120,192 seeds/ha, 300 kg N/ha (300 kg N/ha applied both in 2009 and 2010); 4) 90,580 seeds/ha, 0-N; 5) 2) 90,580 seeds/ha, 300 kg N/ha (0-N in 2009; 300 kg N/ha in 2010); 6) 90,580 seeds/ha, 300 kg N/ha (300 kg N/ha applied both in 2009 and 2010). The first three treatments are considered as an intensification of the last three, which represent the traditional farmers’ practice.

Yields responded to N, regardless of its application sequence. The application of 300 kg N/ha increased grain yields from an average of 1.9 t/ha to 10.9 t/ha, a reflection of significantly greater Harvest Index, more ears/ha, and larger ears with heavier kernels. Partial Factor Productivity and Agronomic Efficiency were 36 and 30 kg grain/kg N, respectively. No significant differences in grain yield could be detected between the intensive and traditional management options, although plant population at harvest differed significantly between them: 91,600 vs. 68,900 plants/ha, respectively. By harvest time, the plant population under both management systems had decreased by 24% on average, which is higher than normal, especially under experimental conditions. Most of that loss (15%) had taken place by the third week after crop planting. IPNI-28