Impacts of the tillage systems on the production of green corn (Zea mays L.) in long-term plots in Northeastern Brazil

In the current global context of climate change and the increasing demand for sustainability, optimizing agricultural production is very important in order to meet the demands for food and to mitigate environmental impact. To achieve sustainable agricultural production, particularly in regions with tropical soil and climate conditions, is necessary to adopt conservation-oriented techniques. This includes no-tillage system, the use of soil-cover crops, and the application of inoculants. The objective of this research was, at the end of the 22nd cropping season, to assess the influence of soil compaction in the production of green corn (Zea mays L.) in a long-term field experiment. This study was conducted under different soil tillage systems in a Red-Yellow Ultisol from the Coastal Tablelands of northeastern Brazil. Three soil tillage systems were applied: Conventional Tillage (CT), Minimum Tillage (MT), and No-tillage (NT). These were combined with four previous crops: cowpea (Vigna unguiculata), crotalaria (Crotalaria juncacea), pigeon pea (Cajanus cajan), and millet (Pennisetum glaucum), as well as two levels of nitrogen fertilizer application: (1) 100% of the recommended N dose, and (2) 50% of the recommended N dose plus Azospirillum brasilense inoculant. The experimental design consisted of strip plots with subplots divided and randomized within each strip, with three replications. Soil compaction was assessed using parameters of soil density (SD) and soil mechanical resistance to penetration (MRP) in conjunction with moisture content (MC). The principal component analysis (PCA) highlighted that conservation-oriented systems exhibited greater soil organic carbon (SOC) levels, leading to increased productivity of commercial green corn cobs. The synergistic effect of diversifying previous crops and adopting conservation tillage systems, especially in soils under long-term tillage, resulted in heightened productivity of commercial green corn ears.