Desempenho de sulcadores na dinâmica dos nutrientes e no desenvolvimento agronômico da soja num sistema de integração lavoura-pecuária submetido a calagem e gessagem

Abstract

The use of integrated systems of agricultural in areas under a no-tillage system improves the soil conditions as long as both are used correctly. If an inappropriate use of these systems is carried out, the areas might present problems both on soil compaction and on nutrients concentration on their superficial layer, which may harm the root growth of plants and the grain yield, especially during long periods of water deficit. Considering all the above-mentioned, the aim of the experiment was to evaluate the nutrient dynamics in soil profile and the agronomic performance of soybean crop implanted with different furrow mechanisms, combined with ways of correting and conditioning soild acidity in an area previously grazed in winter. The experiment was carried out in Vitorino, a town in the State of Paraná, on a distrophic Oxisol, in a field that was cultivated with soy in the summer and black oats for animal grazing in fall-winter. The experiment was carried out in a randomized blocks design, in a bifactorial scheme (2x4) in subdivided plots with four repetitions. In the main plots, two furrow mechanisms were used in the soybean sowing operations were allocated (mismatched double discs and hoe furrow opener). In the subplots, four ways of correcting and conditioning soil acidity were applied (without any corrections; with the recommended dose of limestone - 1 t ha-1; with the dose of gypsum - 2 t ha-1; a gypsum-limestone mixture - 3 t ha-1). The soybean cultivar tested was TMG “7262”. Also, the soil was chemically characterized twice at five different depths. The first time it was characterized six months after the treatment was applied, and on the second time, twelve months after the treatment started. Sowing uniformity parameters as well as yield components and soybean yield in the 2019/20 harvest were also determined. Small changes in pH and calcium and magnesium rates were observed only in the most superficial layers of the soil when it was prepared with the use of mismatched double disks and limestone, but it did not have any effects on deeper layers, nor by the use of gypsum, nor by the use of a hoe furrow opener in the soybean sowing. The use of the hoe furrow opener along with gypsum or its mixture with limestone increased the final stand of soybean plants and the percentage of soybean seedlings with normal spacing. Despite the greater height of insertion of the first pod with the use of mismatched double discs and a greater number of grains per plant with limestone and gypsum, the grain yield was not influenced by the action of the furrow mechanisms and the ways of correcting and conditioning soil acidity, possibly because there was no water limitation during cultivation.