Compactação do solo e fatores operacionais da semeadora-adubadora na distribuição longitudinal da soja

Abstract

During the initial establishment of crops, it is necessary, in addition to an excellent physical and water environment from soil to seed, the correct action of the dosing and distributor mechanisms of the no-till seeder-fertilizer. In this management system, a minimum mobilization of the soil combined with the cutting of the straw is essential for the distribution of seeds in the previously opened furrows. Thus, such cutting devices can help the furrowing efficiency and, consequently, benefit the initial establishment of cultures. The objective of this study was to evaluate the influence of displacement speed and the action of the straw cutting mechanism during direct sowing of soybean under the plant distribution in the field, in soil with different levels of compaction. The study was carried out using a randomized block design, in a split-plot scheme, with four replications. The treatments consisted of no-tillage for ten years and additional compaction induced states by tractor traffic in 2, 4, 6, 8, and 12 passes of wheelsets over the ground. Two speeds of the tractor-seeder-fertilizer set (5.3 and 6.4 km h-1) and two types of cutting mechanisms for covering straw were used. At 21 days after sowing, the stand and longitudinal distribution of plants in normal, faulty and double spacing were evaluated. The data were analyzed by variance analysis and regression. Soil compaction does not influence soybean sowing quality indicators. The speed of 6.4 km h-1 causes an increase in faulty and double spacings between soybean seedlings using the original straw cutting disc. The adapted straw cutting mechanism provides greater efficiency in the longitudinal distribution of soybean seedlings when greater speed is adopted in operation.