Maximum capacity of carbon accumulation in soils cultivated with sugarcane

Author(s)

Carolina Braga Brandani

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2013-08-27

Examining board members

Carlos Eduardo Pellegrino Cerri; Fernando Dini Andreote; Miguel Cooper; João Carlos de Moraes Sá; Carlos Alberto Silva

• Advisor: Carlos Eduardo Pellegrino Cerri

Abstract

One of the main obstacles of sugarcane production in the soil sustainability is the crop management and harvesting. The aim of this study was to evaluate the carbon (C) stocks and dynamics in different SOM fractions in sugarcane systems with or without burning, and under organic fertilization with different periods of adoption (4 and 12) and an area of native vegetation (Cerradão) used as a reference. The study areas are located in Goianésia, GO, all representatives of Latossolos Vermelho-Amarelo distróficos (Oxisols Hapludox distrofic). We evaluated C and N soil contents and natural isotopic abundances 13C e 15N to organominerals fractions < 53 ?m, 75-53 ?m e 2000-75 ?m (organic and organomineral fractions) of SOM. With these results, we aimed to simulate the maximum accumulation of C, by using the Century model, emphasizing different management practices and contrasting soil textures. The C contents were higher for organic-4, in relation to the other areas of sugarcane evaluated. The stocks of C and N were higher for areas where the clay content was higher (burning and organic-4). Due to the difference between soil texture we calculated stocks according to the adjustments on the equivalent mass of soil and clay content, with reference to the native vegetation and thus the largest stocks were observed for organic-12. The C from microbial biomass (C-BM) showed increased in the (C-BM) levels, due to improved management. Regarding the levels of C and N fractions of SOM, the organic-12 and organic-4 resulted in the highest values, especially for OM fraction < 53 ?m (organomineral) to 5 cm depth. These results reflected directly on the values of 13C, the respective proportion of C derived from C4 residue and the 15N, indicating, respectively, greater accumulation and proportion of C derived from the sugarcane in SOM fractions, and evidence from the 15N closer behavior to that observed for native vegetation, relative of OM humification degree. The results of the modeling study emphasized the importance of soil texture and management practices for soil C accumulation. The conservation management system resulted in higher C stocks, by 78% and 98% when simulated soil with higher and lower clay contents, respectively. The results supported the use of the Century model in practical applications of C accumulation in soils cultivated with sugarcane, especially for C stocks and 13C of soils evaluated, indicating that the Century model can be an important tool to establish appropriate management strategies to increase soil C stocks over time. The long period of evaluation showed that concepts such as the \"steady state\" of soil carbon, can be investigated via modeling. We concluded that the practices of the conservation tillage systems tend to increase the stocks of C and N in the soil over time, and this increase is strongly influenced by the clay content in the soil. (AU)

• FAPESP's process: 10/16095-2 - Maximum capacity of carbon acumulation in soils cultivated with sugar cane under differents amounts residues
• Grantee: Carolina Braga Brandani
• Support Opportunities: Scholarships in Brazil - Doctorate