Effect of Sugarcane Harvesting Systems on Soil Organic Matter in Northeastern Region of Brazil

Abstract

ABSTRACT Burning of sugarcane residues has been associated with several environmental and human health problems. In order to alleviate these problems and maintain sustainability of the system, sugarcane industries have started to adopt a mechanized method of harvesting that does not include burning of the residue. The objective of this study was to evaluate the impact of the conversion of burnt to unburnt sugarcane harvesting systems on soil organic carbon (SOC) stocks and soil organic matter (SOM) compartments of the northeastern region of Brazil. The study was carried out in two sugarcane mills in the state of Alagoas. In each farm, chronosequences or comparison pairs were selected, totaling seven areas (three burnt and four unburnt). The unburnt system in the conditions of the northeastern region of Brazil accumulated carbon (C) in the soil at rates similar to those found in the south-central region of Brazil (2.00 Mg C ha−1 year−1). Therefore, the results obtained contribute to consolidating the results of other studies and reinforce the potential of the unburnt system to promote the soil C sequestration, which is important considering the area cultivated with sugarcane. Under the qualitative point of view, the unburnt systems resulted in lower values of soil bulk density and higher values of SOC stocks, fulvic and humic acids, and also of C fractions with greater stability, which are positive indicators that this type of system is gradually improving the quality of the soils.