Effects of sugarcane cropping on organic carbon properties of the soil

With the expansion of the sugarcane cropping area in Brazil, it is necessary to study the changes that this crop may affect to the soil organic matter storage (SOM). The aim of this research was to quantify the carbon management index (CMI), total organic carbon stocks (TOC), labile carbon (LC) and carbon amount in the oxidized fractions of SOM in cropping soil cultivated by sugarcane crop. The experiment was carried out in the sugarcane crop farm located in a dystroferric Red Latosol. The experimental design was completely randomized with four replications. The treatments were comprised of: reference area (RA), area cultivated with sugarcane crop for one year (AC1yr), two years (AC2yr), three years (AC3yr), and four years (AC4yr). The soil samples were collected at two depths (0-10 and 10-30 cm). The highest TOC stock was observed in the treatment AC4yr (15.32 Mg ha-1), which differed from the RA (11.01 Mg ha-1) at 0-10 cm depth. No significant difference was observed in LC at 0-10 cm depth. The treatment AC3yr and AC4yr showed the highest value of LC stocks differing from RA and AC1yr (10-30 cm). There was significant increasing in total organic carbon stocks and labile carbon, indicating the capacity of sugarcane crop on mitigation of greenhouse gases. It also promoted a balanced distribution in the TOC stocks in the fraction of oxidized OM (F1+F2 and F3+F4).