Chemical and physical properties of a vertisol soil cultivated with sugarcane

In the Santa Rosalia sugar mills, in Tabasco, Mexico, 8200ha have been dedicated to the monoculture of sugarcane for over 30 years. Mechanization and a low dose of NPK fertilizers applied on the Vertisol soil, affect the physical properties of the soil and its productivity. The purpose of this study was to evaluate the changes in the chemical and physical properties of a Vertisol soil cultivated with sugarcane. Treatments consisted in four different durations (5, 10, 20 and 30 years) of continuous soil usage, with twelve repetitions each one except for the control, a virgin soil with only four repetitions. At each site, a compound sample was obtained with 3 sub-samples of soil from the furrow and 3 from the interfurrows, 0 to 30cm in depth. The treatment for the year zero corresponded to a medium perennial rainforest. The variables studied were pH, MO, Nt, P K, Ca, Mg, Na, CIC, texture, and bulk density (Da). The Vertisol soil cultivated with sugarcane tends to modify its chemical properties. The pH, P K and CIC levels were maintained through the years and are considered as the only factors for soil fertility stability. MO and Nt decreased, implying the loss of soil fertility and consequently instability. Texture (clay) and Da (1.4g(.)cm(-3)) were not modified by cane monoculture under the conditions of this study. The changes observed in the Vertisol soil cannot be generalized to other types of cane culture soils in the area and similar studies must be carried out for each type of soil.