Soil aggregation and carbon stabilization in burn and no-burn sugarcane management systems

Abstract

Retaining sugarcane straw over the soil after harvesting can improve soil structure and increase soil carbon stabilization, mainly in macroaggregates. We evaluated the carbon content in the aggregate classes in areas under burn and no-burn (adopted for five years) sugarcane management systems, focusing on the superficial layer (0.00-0.20 m). The experiment was carried in an Oxisol and the treatments consisted in burnt sugarcane, manual harvest; burnt sugarcane, mechanized harvest; and no-burn, mechanized harvest. The retention of sugarcane straw on the soil surface is justified by the increase in carbon content and carbon stock in the surface layer (0.00-0.20 m) by restructuring of the soil, even though it cannot match the structure of the soil under native forest. Our results suggest that in no-burn management the carbon not occluded inside aggregates was important to increase carbon stabilization in soil and that more attention should be given to macroaggregates 2.00-8.00 mm present in this management system, that showed higher carbon content and was responsible for increase of the geometric and weight diameter, increasing the erosion resistance in the long term in relation to burn systems.

Sugarcane straw removal for bioenergy production: implications on plant and soil responses

“…Conversely, various agronomic benefits for the soil-plant system are also associated to the retention of sugarcane straw on soil surface , such as: decreasing on soil compaction , reduction of soil erosion process, protection the soil against excessive evapotranspiration and solar radiation, leading to higher soil-water infiltration and availability (Ronquim, 2010;. In addition, because of straw retention on the soil surface, there is an increase of biological activity (Rosseto et al, 2008;Paredes Jr. et al, 2015),soil carbon stocks Leite et al, 2018), soil-macroaggregate formation (Guimarães et al, 2018) and nutrients cycling Almeida et al 2015).…”