Response of maize to potassium in La Frailesca, Chiapas, México

Low soil K is widespread in the sandy acid soils of the La Frailesca region of Chiapas, Mexico. Maize response to K applications in acid soils depends on effective amelioration of the acidic condition. In 2015, we conducted studies in four farms where soil acidity in the top 30 cm of soil was not severe (pH 5.3, and exchangeable Al of 10%) to measure the response of maize to 0, 90, 180, and 270 kg K₂O/ha. Soil exchangeable K averaged 0.2 cmol/kg of soil.

Maize grain yield increased significantly from 3,395 kg/ha when no K was applied to 4,970 kg/ha with 90 kg K₂O/ha, a 46% increase. Yields at higher K application rates did not differ statistically among themselves, nor from the yield at 90 kg K₂O/ha (5,020 and 5,405 kg/ha for 180 and 270 kg K₂O/ha, respectively).