Effect of gypsum and potassium on corn yield and on the exchangeable bases of an acid soil in La Frailesca, Chiapas

Abstract

Objective: To evaluate the residual effect of gypsum in corn crops (2 years after its application in a previously limed soil), as well as the result of a new addition of gypsum combined with potassium in La Frailesca, Chiapas, Mexico. Design/Methodology/Approach: We used a composite factorial design. The initial arrangement (2017) consisted of four levels of gypsum (0, 1.25, 2.5, and 5 t ha-1) and four levels of potassium (0, 60, 120, and 180 kg K2O ha-1). In 2019, the gypsum-treated plots were divided in half: the same amount of gypsum applied in 2017 was added to the first half and the other half was used to assess the residual effect of the initial treatment. The potassium doses were the same as the original. Corn grain yield, pH, exchangeable bases, and aluminum saturation percentage were measured at 0 to 7 and 7 to 14 cm below ground level. Results: The greatest effect on yield was obtained with 2.5 t ha-1 of gypsum applied in 2017; no significant increases were recorded with higher gypsum doses. The exchangeable calcium content and pH level increased, while magnesium, potassium, and aluminum in the soil decreased. Study Limitations/Implications: Suspected presence of Tar Spot Complex was diagnosed. Findings/Conclusions: An excessive application of gypsum generates an imbalance in exchangeable potassium and magnesium in the soil; therefore, producers must exercise caution in the use of these products as part of their fertilization plan.