After four years of the first lime application in a permanent field experiment with cotton, the liming was reapplied with the same previous levels (1.5, 3.0 and 6.0 t/ha) of dolomitic limestone, except for the test treatments where the lowest dose was used. Annual fertilizations of 60 kg N/ha, 0, 60 and 120 kg P2O5/ha and 40 and 80 kg K2O/ha, were carried out. The experiment was conducted in an acid, clayey soil, rich in organic matter: a Dusky-Red Latosol. The pH value at the superficial soil layer was kept around 6.0, with the reapplication of 6.0 t/ha of limestone, and near the value of 5.5, at 20-40 cm depth, due to leaching of alkaline cations. Cotton yields and values of pH and Ca + Mg from the soil analysis increased linearly with liming. However, the effect of ordinary superphosphate upon cotton yield, decreased with liming, showing a negative correlation. The data of phosphorus extracted by anion-exchange resin method showed low variability and high correlation with the soil pH values, during the four years of study. For this reason, the ion-exchange resin method was considered more adequate than the 0.05N H2SO4 method. Appreciable decreases in leaf concentrations of some macronutrients and micronutrients were observed with the high application of limestone and superphosphate, as a rule to recover acid soils, and indicated the need of readjusting the cotton fertilization with regard to the levels of K and B, specially.
dolomitic limestone; ordinary superphosphate; correlation between liming and phosphorus; leaching of basic cations; and leaf blades analyses