In order to evaluate the viability of corn planting in a soil under reduced tillage, a field trial was conducted in Passo Fundo (Rio Grande do Sul, Brazil), in December, 1988. In the control plots, soil tillage consisted of chisel plowing and disking. In the other five treatments, tillage was done through a conjugated operation (chisel plow with a clod break roller). In the control and in one of the other treatments, the configuration of each line of the planter-fertilizer consisted of two sets of double disks and a press-wheel. For the other four treatments, ondulated disk colters, or sections of packer rollers, were adapted in front of the lines of the planter-fertilizer. Two days after planting, the percentage of soil cover by residues was significantly lower (Tukey test - 5%) in the control, whereas there were no differences between the treatments and hence the latter were characterized as conservation tillage. The geometric mean diameter (GMD) of the soil aggregates did not differ between treatments. However, the aggregates collected in the rows showed significantly lower GMD than those collected between rows. Water absorption speed of the seeds, radicle length, emergence velocity index and initial plant stand did not vary significantly as a function of the treatments. The results show clearly that reduced tillage through a chisel plow equipped with a clod break roller allowed the planting of corn without secondary tillage operations and without modifications on the planter-fertilizer.
reduced tillage; chisel plow; planting; maize