Soil Pathogens and Straw Removal in Sugarcane

The presence of straw in agricultural areas directly influences the soil microbiota, contributing to pathogen suppression, moisture retention, and increased carbon sequestration. In sugarcane cultivation, management practices such as straw removal may favor soil-borne phytopathogenic microorganisms, such as Fusarium oxysporum, Pythium sp., and Rhizoctonia solani, which compromise root systems and reduce crop productivity.

This study aimed to evaluate the effects of straw removal and irrigation systems on the soil pathogen community and total organic carbon (TOC) content in sugarcane fields in the Cerrado. The experiment was conducted in Goianésia, Goiás, Brazil, in a typical dystrophic Red Latosol, with clayey texture, average pH of 5.2, and organic matter content of 2.4%. A completely randomized design was used in a 3 × 3 factorial scheme (three irrigation systems: sprinkler, center pivot, and rainfed × three straw management regimes: no removal, one-year removal, and two-year removal), with four replications. Soil samples were collected at a depth of 0–20 cm. The abundance of Fusarium oxysporum, Pythium sp., and Rhizoctonia solani was evaluated using selective culture media, and TOC was quantified. Data were analyzed by analysis of variance (ANOVA), and means were compared using Tukey’s test (p < 0.05).

Results showed that plots with straw retention had significantly lower concentrations of Fusarium oxysporum (5.2 × 10³ CFU/g soil) compared to areas with two years of straw removal under sprinkler irrigation (1.1 × 10⁴ CFU/g soil). Pythium sp. was more prevalent in rainfed areas with two years of removal (8.7 × 10³ CFU/g), statistically differing from the other treatments. TOC levels were higher in straw-covered plots (22.4 g/kg) compared to those without straw (16.1 g/kg). The presence of Trichoderma spp. was also higher in straw-retained soils (6.3 × 10³ CFU/g), suggesting a potential antagonistic effect.

It is concluded that straw removal favors pathogen incidence and reduces soil organic carbon, while straw retention promotes greater abundance of beneficial microorganisms. Practices that preserve straw cover contribute to soil health and the sustainability of sugarcane production in the Cerrado.