Response of Two Maize Cultivars to Potassium in Cintalapa

The objective of this study is to determine the responses of an open pollinated variety and a hybrid of maize to K fertilizer applied using two sources and at four rates. The study was conducted in a farmer’s field in Cintalapa, Chiapas, Mexico on a sandy clay loam soil (pH 5.5, 2.4% organic matter, 51 ppm Bray 1-P, 48 ppm available K, 1,214 ppm Ca, 213 ppm Mg, 18 ppm Na, 0,7 ppm Zn, 32 ppm Mn, 2 ppm Cu, and 0,2 ppm B). The effective cation exchange capacity of the experimental soil was 8 cmol/kg. Treatments included two cultivars (variety ‘V 424’ and hybrid ‘P4063W’), two K sources (KCl and K₂SO₄) and four K rates (0, 60, 120, and 180 kg K₂O/ha). The resulting 16 treatments with 2 replications were arranged in an experimental design with split-split-plots, where the cultivars were assigned to main plots, sub-plots had K sources and sub-sub-plots had K rates.

Maize grain yield averaged 2.6 t/ha (14% moisture) because of the drought that affected the location. No significant effects (p=0.05) could be detected for any treatment. Average yield for the hybrid (3.5 t/ha) was almost twice as high as that of the open-pollinated variety (1.8 t/ha), which could be due to several factors including open-pollinated variety's lower tolerance to drought and more severe damage by fall armyworm in the season.