The Need for P and K in "La Fraylesca Soils" - Heart of Corn Production in Southern Mexico
La Fraylesca is a corn producing region in the State of Chiapas, Mexico, where acid soils are the result of erosion, high summer rains and continuous crop cultivation. According to FAO the predominant soils of the region are "cromic Cambisols" (Bc), eutric Regosols (Re) and eutric Cambisols (Be). All these soils are very susceptible to erosion and show low natural fertility (low cation exchange capacity, CEC). The main corn producing area is located around Villa Flores and Villa Corzo, and as we can see from Figure 1, Bc soils dominate. Other classifications refer to these soils as Andisoils due to their volcanic origin. Despite this volcanic origin, available P is low due to soil acidity that ranges from <3.9 to 5.5. Potassium (K) levels range from less than 50 to 200 ppm due to the low CEC and sandy textures. Corn has been grown for thousands of years in this region, with very low inputs of P and K, and as a consequence yields have been very low and unprofitable.
Figure 1. Soil Types of "La Fraylesca" Region in Chiapas, Mexico.
INPOFOS has been working in the region for more than five years to demonstrate the effect of combining Ag-lime, P, K and balanced fertilization together with changes in corn producing technology. Results of five years of demonstration trials are summarized in Table 1. Phosphorus and K applications will only have an impact if the soil pH is raised to 5.5. After the pH is raised to >5.5, balanced fertilization with other nutrients like magnesium (Mg), sulphur (S), iron (Fe) or zinc (Zn) may begin to have a positive impact on corn yield.