EFFECT OF DIFFERENT SOIL CORRECTIVES AND GYPSUM ON THE SOIL CHEMICAL CHARACTERISTICS CROPPED WITH RICE AND SOYBEANS

Abstract

Aiming to verify the action of different soil correctives on the chemical characteristics of a dark red latosoil median texture, a two-years field experiment was carried out. A completely randomized design with 7 treatments (6 different soil correctives and a control with no liming) and four repetitions were used. As soil correctives limestone (calcitic, dolomitic, calcinated dolomitic, and magnesian), gypsum and calcium hydroxide were employed. On the first year the experimental area was cropped with rice (Oryza sativa L.) c.v. IAC-25 and on the second one with soybean (Glycine max L. Merrill) c.v. IAC-8. Dolomitic limestone caused the greatest chemical alterations on soil characteristics, with increase on pH, K⁺, Ca⁺² and Mg⁺² and decrease on H⁺ + Al⁺³ values, during the first year. Losses of exchangeable Mg⁺ by leaching have been found during the second year, due to the use of gypsum and calcitic limestone. All liming materials, but gypsum, increased rice yields when compared with the control. The calcinated dolomitic limestone gave the highest soybean yields.

KEY-WORDS: Soil; soil acidity; liming materials; pH.