Impacto do sistema de integração lavoura pecuária nos estoques de carbono e nitrogênio em Latossolo Vermelho de Santo Antônio de Goiás-GO

Abstract

In the last decades, there is a great concern due to the increase of atmospheric CO2 and a growing interest in soil carbon sequestration in the form of soil organic matter (SOM). Soil disturbance caused by agriculture is the primary cause of soil organic carbon losses as CO2. Well-established production systems, such as integrated crop-livestock systems (ICLS) have the potential to contribute to reduction of atmospheric CO2, mitigating the consequences of greenhouse effect. For that, nitrogen availability is essential, once associated with carbon it constitutes the more stable fraction of SOM (humic substances). The objective of this study was to evaluate an ICLS in a Cerrado biome, located in Goiânia, state of Goiás. It is a long-term experiment (15 years), studying the Santa Fé integrated system and it started under a conventional crop production. Treatments consisted of six ICLS areas, a continuous pasture and a Cerrado native area, that was used as an isotopic control and soil carbon stock reference. ICLS areas had different integration times, so that when the samples were collected, areas 1, 2 and 6 were under pasture and areas 3, 4 and 5, under corn, soybean and rice production. Areas 1 and 2 were cultivated with green manure during 4 years, and they were under fallow most of the time. Results of isotopic techniques using 13C in Cerrado native vegetation showed that, in a geological timescale, this area used to be covered predominantly by C4 cycle plants. Using the same technique, when compared to native vegetation, it showed that continuous grassland preserved more of the original soil carbon, even deeper than 60 cm. Carbon stocks in the areas of continuous pasture and pasture areas ICLS were equal to the cerrado (t-Bonferroni 5%). The ICLS areas under crops presented the lowest carbon stocks (t-Bonferroni 5%). In the areas 1, 2 and under continuous pasture, it was observed the largest stocks of carbon of the management systems, which were associated to the lower cultivation intensity.