Global Maize Project in Mexico: Celaya, Guanajuato

The study started in 2009 in Celaya, State of Guanajuato, at 1,830 meters above sea level, in an environment classified as non-equatorial, tropical–subtropical, mid-altitude. In 2012, the design of treatments was modified to include a combination of two plant populations: Farmers’ practice (FP) (89,286 seeds/ha) and a higher population (119,048 seeds/ha), three N fertilization regimes (0 N always, 0 N following 300 kg N/ha applied in 2011, and 300 kg N/ha applied every year), and two levels of P+K+Mg+Zn (0 and 90 kg P₂O₅/ha + 150 kg K₂O/ha + 25 kg MgO/ha + 10 kg Zn/ha). Treatments were arranged in a split-split-plot design, where plant populations, N fertilization regimes, and P+K+Mg+Zn were assigned to large, sub-, and sub-sub-plots, respectively.

Plant populations at harvest differed significantly between FP (67,370 plants/ha) and the higher population (86,311 plants/ha). Average stand reduction between planting and harvest for both populations (24%) was greater than normal. This reduction was probably due to soil crusting at seedling emergence and losses to wildlife. However, population differences did not result in significant average grain yields differences between FP (5.27 t/ha) and the higher population (5.62 t/ha) treatments. Grain yield with the application of 300 kg N/ha (11 t/ha) was significantly higher than the grain yields obtained with 0 N following 300 kg N/ha applied in 2011 (2.84 t/ha) and 0 N always (2.49 t/ha). The latter two did not differ statistically. Partial Factor Productivity (PFP) and Agronomic Efficiency (AE) of N were 37 and 28 kg grain/kg N, respectively. No significant differences in grain yield could be detected between the two levels of P+K+Mg+Zn used in the experiment (5.48 vs. 5.41 t/ha). These results were consistent with the soil test values for these nutrients. IPNI-28