Mechanical Intervention in Compacted No-Till Soil in Southern Brazil: Soil Physical Quality and Maize Yield

Abstract

The intense and successive use of mechanization in modern cropping systems has increased soil compaction under no-till areas. In this study, we aimed to assess the performance of a fixed shank coupled with a seeder for the mitigation of soil compaction induced by machinery traffic as an efficient alternative to replacing the chiseling and subsoiling operations in no-till areas. We evaluated a long-term experiment conducted in clay loam (Rhodic Haplustox) soil in southern Brazil. The experiment was conducted under a randomized block design, whose treatments consisted of three wheel-traffic intensities: 0 wheel-traffic (0 WT), 14 wheel-traffic (14 WT), and 28 wheel-traffic (28 WT), combined with four soil tillage mechanical interventions under a no-till field: no-till (NT), no-till with a fixed shank (NT + FS), soil chiseling (SC), and soil subsoiling (SS). The soil physical attributes evaluated were the soil penetration resistance (SPR), macroporosity (MaP), microporosity (MiP), total porosity (TP), bulk density (BD), field-saturated hydraulic conductivity (Kfs), S index, and plant-available water capacity (PAWC). In addition, three critical soil physical functions were evaluated by using a soil physical quality index (SPQI). The results showed that SPR was sensitive to soil compaction and captured differences among the mechanical intervention methods. Machinery traffic caused soil compaction, increasing SPR and reducing PAWC. Soil chiseling and subsoiling promoted lower BD, a higher TP, MaP, Kfs, and higher S index at the 0.05–0.15 m soil layer. Based on the SPQI, no changes were detected in the soil physical functions between NT and NT + FS. On the other hand, SC and SS enhanced soil physical functioning by 10%. We concluded that a 15-cm deep fixed shank could not mitigate the soil compaction induced by machinery traffic at the seeder operation. Therefore, this method is less effective in improving the soil’s physical environment than chiseling and subsoiling operations. Finally, we encourage monitoring the persistence of these benefits on the soil over the subsequent crop seasons and in years with an intense water deficit along with the crop cycle.