Rendimento de grãos e decomposição de resíduos de soja em cultivo tradicional e em sistema de integração lavoura-pecuária

Abstract

The integrated systems of agricultural production (ILP) aim to associate two activities in the same area, farming and livestock, making it a complex system that encompasses physical, chemical and biological factors of the soil, in addition to the recycling of nutrients. The soils of the southwest of Paraná are characterized by their depth and presence of toxic aluminum in their solution, which leads to reduced crop development; liming and plastering are techniques performed to change this scenario, leaving the soil less acidic and more productive. Based on this, the present study aimed to analyze the effect of different soil corrections, associated with different seeding methods, in the crop-livestock integration systems (area pastured in winter) and no-till farming (area without pasture in winter), on the productivity of soybean cultivation (Glycine max(L.)), in addition to evaluating the residual decomposition of this crop. The experiments (one on grazed oats in winter and the other on unpastected oats) were conducted in an integrated system of cattle ranching and direct planting in the municipality of Vitorino-PR, in the 2 x 4 bifatorial scheme, in subdivided parcels. In the main plot, the combinations of two seeding methods (mismatched double disc and furrower rod) were allocated; and in the sub-plot, four different corrections (no correction, recommended dose of plaster, recommended dose of limestone, recommended dose of plaster + recommended dose of limestone), in the random block design, with four repetitions. The productive variables analyzed were plant height (AP), first pod insertion height (AIPV), number of plant-1 pods (NVP), number of pod-1 grains (NGV), grain yield (Kg ha-1) (REND) and weight of 1000 grains (g) (PMG). For the yield components were initially verified the assumptions of the anova and then performed analysis of variance in bifatorial scheme, 2 x 4, in subdivided plots, in DBA, at a level of 5% probability of error, deploying the interactions by means of the Tukey test for comparison between means, when necessary. For the analysis of dry mass decomposition (MS), analysis of variance was performed, and subsequently, the interactions were unfolded adjusting a simple exponential model for each situation studied. The data were analyzed using the computer program RBIO and GENES and the graphs generated in the program SigmaPlot®, version 12.5. For the experiment carried out in pastegnated area, NGP was higher when sowing with a furrower rod and the highest PMG was obtained by associating the use of furrower rod with correction via limestone. For the non-pastejo experiment, the use of a mismatched double disc showed higher grain yield, as well as a higher insertion height of the first pod, when associated with correction using plaster. The decomposition of soybean crop residues is accelerated, as well as other leguminous species, promoting a low soil coverage.