Banca de DEFESA: VANESSA CRISTINE SERRA PEREIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : VANESSA CRISTINE SERRA PEREIRA
DATE: 02/02/2024
TIME: 09:00
LOCAL: Departamento de Agrotecnologias e Sustentabilidade
TITLE:

Carbon and Nitrogen Stocks and Soil Aggregation in Different Sustainable Agricultural Production Systems and Native Vegetation in the Cerrado

KEY WORDS:

Protocolo MRV. Carbono Orgânico Particulado (COP). Carbono Orgânico Associado aos Minerais (COAM). Matéria Orgânica. 

PAGES: 50
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Manejo e Conservação do Solo
SUMMARY:

Brazil ranks fourth among the largest emitters of greenhouse gases (GHG), due to changes in land use and agricultural production. In this scenario, the Cerrado biome stands out, which reduced 152.7 thousand km2 of its natural vegetation, which can result in changes in the biogeochemical cycles of C, N, P and S. One of the biggest challenges for the agricultural sector is adopting management strategies for the sustainable soils that contribute to the recovery of degraded areas that help to mitigate GHG emissions and that promote the fixation of C in the soil in the form of soil organic matter (SOM). This study had the general objective of evaluating C and N stocks, soil aggregation, as well as the active and stable fractions of SOM, under different sustainable agricultural management systems, comparing them with areas of native vegetation, in the Cerrado biome. . The study was carried out on a farm located in the city of Unaí in the State of Minas Gerais, evaluating three treatments: i) Native Forest (MN); ii) Productive Pasture (PP) and; iii) Crop-livestock integration (ILP). In each treatment, 3 trenches were opened and deformed and undisturbed soil samples were collected at depths 0-5, 5-10, 10-20, 20-30, 30-40, 40-60, 60-80 and 80-100 cm. . Physical and chemical analyzes of the soil and C and N contents were carried out at all depths sampled. The C and N stocks were made in layers 0-10, 0-30 and 0-100 cm and the particle size fractionation of the SOM (0-5, 5-10, 10-20 and 20-30 cm). Furthermore, blocks of earth were collected in the same trenches at depths of 0-5 and 5-10 cm, to determine the stability of soil aggregates. The experiment was carried out using a randomized block design (DBC), with three replications. For statistical analysis, analysis of variance was applied with the mean comparison test using the Tukey test at 5% significance. The results showed that C levels and stocks in the soil were higher in PP than in MN. This result may be due to the non-disturbance of the soil by agricultural machinery and the greater deposition of organic material on the surface and subsurface. The same behavior was observed for N contents and stocks, except in the 0-100 cm layer where no statistically significant difference was observed between MN and PP. The ILP system remained the same as MN, differing statistically in terms of C content only at depths of 40-60 and 60-80 cm. However, C stocks were reduced in the ILP (~ 47 Mg C ha-1), presenting approximately half of the C stocks in the MN and only 31% of the C stocks in the PP. A likely explanation is the short time it took to implement this system, just four years. These results were reflected in the labile and stable fractions of SOM. For particulate organic carbon (COP), the PP area presented the highest concentrations in the superficial layers (0-5 and 5-10 cm), not differing from the MN in the other depths evaluated. The explanation is the contribution of roots. For organic carbon associated with minerals (COAM), which is stable carbon, that is, fixed in the soil, the removal of MN to PP did not result in any difference. The PP was equal to or greater than the MN at the depths evaluated. The largest weighted average diameter of soil aggregates was in MN and PP, which did not differ statistically at the two depths. It is concluded that, by evaluating the physical and chemical attributes of the soil, the PP soil management system can be used in Unaí, Cerrado biome, aiming to maintain soil safety. The ILP system has the potential to be used, the results obtained are a reflection of the short implementation time of this system, requiring a longer period of monitoring.

COMMITTEE MEMBERS:
Presidente - 1740899 - ERIKA FLAVIA MACHADO PINHEIRO
Externa à Instituição - ANA CAROLINA DE SOUZA FERREIRA
Externo à Instituição - EDNALDO DA SILVA ARAÚJO - EMBRAPA