Machinery traffic in sugarcane straw removal operation: Stress transmitted and soil compaction

Abstract Straw removal requires a complex set of mechanized operations, including machines for raking, baling, and transporting the straw, which may intensify soil physical degradation in sugarcane fields. A field experiment was conducted to estimate the stress transmitted caused by a set of machines used for sugarcane straw removal and to quantify the impact of these stresses on soil physical indicators. The treatments consisted of reproducing the field traffic of individual and sequential operations used for straw removal, including raking; raking + baling; and raking + baling + transporting operations. Soil bulk density (BD), soil penetration resistance (SPR), macroporosity (MaP) and microporosity (MiP) at the depths of 2.5, 5, 15, and 30 cm were measured before and after the field operations. Contact area of the tires and stress transmitted into the soil induced by the straw removal operations were simulated by SoilFlex model and then used to assess the magnitude of the changes in soil physical indicators. Results showed that baling operation transmitted the highest stress (∼400 kPa), followed by straw raking and transporting, whose transmitted stress level exceed 300 kPa near the soil surface. The sum of sequential operations (i.e., raking + bale + transporting) showed the highest negative impact on soil physical quality. The magnitude of the changes in soil physical indicators occurred according to initial conditions of BD and transmitted stress. Our results show that operations for straw removal intensify soil compaction, which can be detrimental to sustain soil health and plant growth. Therefore, we advocate that traffic control strategies should be adopted during the straw removal operations to improve soil quality towards greater sustainability of sugarcane production in Brazil.