Soil physical quality associated with tillage practices during sugarcane planting in south-central Brazil

Soil tillage operations had been carried out during the sugarcane planting to improve soil's physical quality, thus providing proper conditions for sugarcane growth. Long-term field experiments were designed to assess the implications of tillage operations during sugarcane planting on soil physical quality and the associated effects on sugarcane yields under two soil types in south-central Brazil. In 2013, two treatments were arranged in a randomized block design with four repetitions: (i) conventional tillage (CT) and ii) no-tillage (NT). Undisturbed soil samples were collected representing the row and inter-row positions to a 0.40-m depth (0-0.10, 0.10-0.20 and 0.20-0.40 m) over four crop cycles (from 2014 to 2017). In the laboratory, bulk density (BD), soil resistance to penetration (SRP), snacroporosity (MaP) and microporosity (MiP) were evaluated. Additionally, sugarcane yields were measured annually using an instrumented truck equipped with load cells. CT management alleviated soil compaction only in the plant cane cycle, indicating that the intensive machinery traffic performed in sugarcane harvesting nullify the effects of tillage practices. The opening of planting furrow in both tillage systems reduced soil physical limitations, thus favoring the crop development in the row position. The changes in soil physical attributes were observed mostly in the inter-row position. In clayey soil, BD increased by 24 and 16%, and the SRP by 63 and 55% in the 0-0.10 m layer from plant cane to 3rd ratoon for CT and NT, respectively. Similarly, in sandy loam soil, the SRP increased over time in the 0-0.10 m layer for CT and NT, reaching values higher than 2 MPa. Likewise, MaP decreased for values lower than 0.10 m(3) m(-3) after four years for both soils and tillage systems. Regardless of soil type, tillage management did not show differences in sugarcane yields over the assessed period. Our findings suggest that NT could be a feasible strategy to reduce soil mobilization and its negative implications on several ecosystem services without compromise sugarcane yield. (AU)