Influence of sugarcane management on the carbon management index and soil aggregation

Abstract

This study aimed to evaluate the physical fractions of soil organic matter (SOM), carbon management indexes (CMI), and the aggregation in soil areas of sugarcane cultivation. Five sugarcane cultivated areas were evaluated, in addition to a reference area of native forest (NF). Samples of disturbed soil, soil layers and undisturbed were collected In the disturbed samples, total carbon (TC), physical-granulometric fractionation of SOM were determined with subsequent CMI calculations. Aggregation analysis was performed in the undisturbed samples, and the weighted mean diameter (WMD), geometric mean diameter (GMD), and percentage of aggregates retained in the different sieve classes were determined, in addition to determining the TC contents of each aggregate class. The NF presented the highest levels of TC, particulate carbon (C-POM), and mineral carbon (C-MOM). Among the managed areas, the area that received filter cake and vinasse application stood out with higher TC, C-POM, and C-MOM levels in the most subsurface layer. All areas cultivated with sugarcane presented CMI lower than the area with NF. The worst aggregation indexes were observed in the area with management with burning in the pre-harvest and only filter cake application. The best aggregation indexes were in the NF. The area with the practice of burning, but with the joint application of filter cake and vinasse for 16 consecutive years, provided the highest aggregation of soil and best CMI among the areas cultivated with sugarcane.