Carbono e nitrogênio das frações da matéria orgânica do solo de sistemas de manejo com e sem queima na Amazônia Oriental.

Abstract

In the Amazon, the system off cutting and burning of vegetation for land preparation, traditionally used the context of family farming has contributed to loss of soil organic matter (SOM). The MOS is an important reservoir of chemical elements (nutrients) emphasis on carbon (C). Inadequate management practices. intensive cultivation and deforestation cause changes in its dynamics and, consequently reductions in the stock of C and N in te soil. Thus, the study of the dynamics of the fractions that compose it, become a fundamental tool for understanding the effects of agricultural management systems in the accumulation or loss of soil carbon and nitrogen. The objective of this study: (1), evaluate the effect of systems with and without burning te stock of C and N of soil and organic matter fractions (2) to compare methods for determining the concentration of C in the soil using, as a case study, experimental areas of cutting and burning and cutting and grinding. The experiment was conducted in Igarapé- Açú (PA). We evaluated te following treatments: (1) system with preparation area with crushing vegetation and fallow enrichment with leguminosus trees, (2) system with preparation area with burning vegetation and (3) secondary forest with more than 20 years (capoeira). The results evidenced: (a) All systems have reduced the stock of soil C and N (b) The system with grinding and fallow enrichment promotes greater accumulation of C and N in the light fraction and the particulate soil organic matter, compared to the system with burning; (c) the stock of C and N from labile suffer effect of systems and the collection period, (d) methods for quantification of C has a high correlation (e) the combustion methods via wet underestimated the values of C and (f) the data from C by weight loss on ignition, you can use your regression to estimate with confidence the results of C by dry combustion.