Plantabilidade de milho em função de métodos de manejo de palhada e mecanismos sulcadores

Abstract

Corn sowing, especially in no-tillage systems, is decisive for productivity due to the crop's sensitivity to inadequate management. No-tillage systems uses vegetation cover to protect the soil, regulate the microclimate, and reduce erosion. Straw management, carried out by mechanical or chemical methods, directly affects the quality of sowing, influencing the depth of seed deposition, stand uniformity, and seedling emergence. Furrowing mechanisms, such as rod, double disc, and guillotine openers, play a fundamental role in crop plantability. The rod-type furrower mobilizes more soil, allowing greater depth and better seed-soil contact, while the double disc is efficient in soils with high vegetation cover, but finds it difficult to cut straw. The guillotine furrower combines versatility and lower traction resistance, with moderate impact on the soil. With the objective of evaluating corn plantability parameters based on straw management methods and furrowing mechanisms, the present work was developed in the municipality of Renascença 3 PR. A factorial scheme (3x2) was used, with three furrowing mechanisms (furrowing rod, mismatched double discs and guillotine) and two straw management (desiccated and rolled), in a randomized block design, with four replications. The results showed that the rod-type furrower provided greater seeding depth and better emergency velocity index (EVI), due to favorable soil moisture conditions. Straw management did not show significant differences for these indicators. The vegetation cover presented adequate levels of dry matter (>6,000 kg ha-1), benefiting moisture retention and the gradual release of nutrients. However, dense straw can make it difficult for furrowers to cut and compromise the performance of the seeder. The initial and final plant stand did not vary significantly between treatments, but the rod-type furrower demonstrated an advantage due to its greater effectiveness in breaking the soil and avoiding seed-soil contact failures. However, the uniformity of plant distribution was similar between treatments, confirming the efficiency of the adjusted machinery. It is concluded that the choice of furrowing mechanism and straw management must be adapted to local soil and cultivation conditions. These practices, aligned with good operational conditions, are essential to maximize corn productivity in the direct planting system.