Organic cultivation of sugarcane restores soil organic carbon and nitrogen

Abstract

Sugarcane cultivation in the Cerrado biome causes changes in soil attributes and affects the sustain- ability of agricultural production. The organic system may constitute an alternative to the conventional system. We have hypothesized that (i) the replacement of native Cerradão vegetation to sugarcane cultivation in a con- ventional system modifies the physical and chemical attributes of the soil and that (ii) organic cultivation may contribute to restoring physical and chemical prop- erties that have been degraded by conventional cultiva- tion. The study consisted of the following areas: (a) Cerradão, (b) pasture, (c) sugarcane in an organic system (organic sugarcane), (d) sugarcane in a conventional system with straw burning before harvest (burned sug- arcane), and (e) sugarcane in a conventional system without burning the straw before harvest (raw sugar- cane). The soil carbon and nitrogen contents and total soil density and porosity were evaluated. Six soil layers were sampled: 0–10 cm, 10–20 cm, 20–30 cm, 30– 40 cm, 40–50 cm, and 50–60 cm depth. The results have showed that the sugarcane cultivation altered all the evaluated attributes when compared to Cerradão soil. The most significant changes, with a reduction in carbon and nitrogen contents, total porosity and soil bulk density, occurred in conventional cropping sys- tems. In the organic system, there were few changes in the evaluated attributes when compared to the Cerradão ecosystem. In this paper, we show that a reduction in the total nitrogen in the 0–10 cm layer was the only ob- served decline. Organic sugarcane proved to be a viable alternative for production in the Cerrado biome as it restores soil attributes similar to those of the Cerradão ecosystem.