Soil organic and organomineral fractions as indicators of the effects of land management in conventional and organic sugar cane systems

Autor(es)

Brandani, Carolina B. ; Abbruzzini, Thalita F. ; Conant, Richard T. ; Cerri, Carlos Eduardo P.

• Tipo de documento: Artigo Científico
• Fonte: SOIL RESEARCH; v. 55, n. 2, p. 145-161, 2017.
• Citações Web of Science: 5

Resumo

Brazilian sugar cane production has undergone changes in residue management. To better understand the dynamics of soil C and N in soil organic matter (SOM) fractions resulting from sugar cane management practices, we determined: the effects of different sugar cane management on the C and N content of SOM fractions; the effects of crop management, soil texture, depth and different organic matter additions on changes in C-13/C-12 and N-15/N-14 isotope composition; and the amount of SOC derived from different sources. Physical fractionation of SOM was performed for soils cultivated under four sugar cane managements, namely straw burning(SB), green cane (GC) and organic systems consisting of sugar cane grown under GC harvesting with high inputs of organic residues for 4 and 12 years (O-4 and O-12 respectively), as well as from a native vegetation (NV) area (Goianesia, Brazil). Ultrasonic dispersion of soil samples from 0-5, 5-10, 10-20 and 90-100-cm depths resulted in three organomineral fractions (<53, 75-53 and 2000-75 mu m) and one organic fraction denoted as light fraction (2000-75 mu m). C and N concentrations, C-13 and N-15 natural abundance and the proportion of C derived from C4 sugar cane plant residues (C-C4) were determined for each fraction. The C management index (CMI), derived from the total C pool and C lability, is useful in evaluating the capacity of management systems to improve soil quality and was calculated using the NV as the reference. Highest C and N concentrations were found for O-12 and O-4, mainly for the <53-mu m organomineral fraction at 0-5cm depth. The C-13 and C-C4 values indicated a greater accumulation of C-C4 in SOM fractions in organic compared with burned and unburned systems. GC combined with organic management is a strategy for long-term storage of total C and N in the SOM fraction associated with <53-mu m fraction and light fraction. In addition, the highest CMI and its positive relationship with C-C4 in O-12 suggest the role of this system to foster soil quality improvement. The results allow infer regarding the potential of management practices on C accumulation in SOM fractions, which, in turn, can be used as indicators of the effects of land management. (AU)

• Processo FAPESP: 10/16095-2 - Capacidade máxima de acúmulo de C em solos cultivados com cana-de-açúcar sob diferentes aportes de resíduos
• Beneficiário: Carolina Braga Brandani
• Modalidade de apoio: Bolsas no Brasil - Doutorado