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 sustainability 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 conventional system modifies the physical and chemical attributes of the soil and that (ii) organic cultivation may contribute to restoring physical and chemical properties that have been degraded by conventional cultivation. 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 sugarcane), and (e) sugarcane in a conventional system without burning the straw before harvest (raw sugarcane). 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 systems. 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 observed 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.