Linking soil physical quality to shoot and root biomass production in scenarios of sugarcane straw removal

Understanding how sugarcane straw removal affects soil physical attributes and root development over successive cultivation years is critical for sustainable straw-based bioenergy production. The aim of this study was to evaluate the effects of straw removal on soil physical quality and its relationship with sugarcane root development and crop yield in soils with contrasting textures. Three straw removal rates corresponding to total removal (TR), moderate removal (MR), and no removal (NR) were arranged in a randomized block design with four replicates. Soil was sampled at depths of 0-0.10, 0.10-0.20, and 0.20-0.40 m to determine soil bulk density, macro- and microporosity, soil penetration resistance, and carbon stock. Annual assessments of sugarcane root and stalk dry biomass were conducted. Overall, excessive straw removal rates were detrimental to soil porosity, C stock, and increased bulk density in the surface layer over successive years compared to moderate and no removal rates. Higher soil penetration resistance levels were observed under total removal, reaching values of 2.6 MPa in the 0-0.10 m layer in both soils. Average reductions in root biomass of 23-33% were verified at moderate and total removal rates in both soils, which affected sugarcane stalk yield, with maximum losses of 24% over crop cycles in the clayey soil. In the sandy loam soil, increases in soil C were correlated with reduced soil penetration resistance, which positively influenced root biomass production. Soil compaction over the years was particularly detrimental in the clayey soil, where the biomass production performance of sugarcane roots and stalk yield decreased in response to increased soil bulk density. Our results suggest that reductions in root biomass may occur in response to straw removal, as well as the loss of soil physical quality induced by soil compaction, with negative effects on C accumulation and soil resistance to root penetration.