Incubação de um latossolo amarelo distrófico com calcários e desenvolvimento do milho

Abstract

Incubating soils with increasing doses of limestone is the safest way of defining the ideal dose for each soil. However, these studies do not take into account plant responses, which can vary depending on the composition of the limestone. Based on this fact, this study was carried out with the aim of evaluating the effects of different limestones on the development of maize. The experiment was conducted in a greenhouse at the Federal University of Mato Grosso. Soil samples were collected from 0 to 20 cm deep in a natural area (native forest), whose soil is classified as a dystrophic red-yellow oxisol. The experimental design was completely randomized (DIC) with four treatments and five replications. The treatments consisted of the three limestones and a mixture of calcitic and dolomitic limestones, called "Blend". The limestones used were: calcitic limestone - 50.7% CaO and 2.45% MgO (PRNT - 86.57%), dolomitic limestone - 30.8% CaO and 21.5% MgO (PRNT - 103.77) and magnesian limestone - 40.6% CaO and 12% MgO (PRNT - 95.46). The limestone doses were calculated with the aim of achieving 60% of the soil's base saturation, while the amount of limestone in the mixture was defined with the aim of obtaining 50% Ca and 10% Mg in the CTC at pH 7.0. The plots where the corn was grown were made up of 6.0 dm3 plastic pots, with humidity maintained at 80% of field capacity through daily weighing. Plant height, ear insertion height, stalk diameter, leaf area, dry mass of leaves, stalks, tendrils, ears, roots and total plant mass were assessed. The values obtained were subjected to analysis of variance using the F test (p< 0.05) and the means were compared using the Skott-Knott test. The results of the analysis of variance showed that the limestones did not influence the morphological characteristics of the maize, except for the diameter of the stalk, but did promote significant increases in the dry mass of the ears and total. It was concluded that: a) limestones have different effects on the development and dry matter production of maize, b) the Ca:Mg ratios of limestones influence the development and dry mass production of maize and c) the addition of dolomitic limestone promotes gains in ear production and total dry mass of maize.