Banca de DEFESA: PABLO ACÁCIO DOS SANTOS SOUZA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : PABLO ACÁCIO DOS SANTOS SOUZA
DATE: 21/02/2022
TIME: 09:00
LOCAL: Defesa remota pelo Google Meet
TITLE:

Microbial biomass and carbon and nitrogen stocks in unglazed and pasture Caatinga areas

KEY WORDS:

Semiarid. Organic matter. Nitrogen and carbon cycling. Use of the soil.

PAGES: 85
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:

In the caatinga, livestock is the main human activity, being able to cause changes over a long time scale. Knowledge about the effect of forage use on microbial biomass and carbon and nitrogen stocks in the Caatinga is limited, however, it is fundamental to understand the flow of C and N, as well as the elaboration of a management plan and sustainable public policies. . The objective of this work is to estimate microbial biomass activity and soil carbon and nitrogen stocks in forage use areas in the Caatinga biome after 3 years of animal exclusion. Five permanent plots of ecological studies were analyzed, implemented in the Experimental Stations of the Instituto Agronômico de Pernambuco (IPA), in the municipalities of Caruaru, São Bento do Una, Arcoverde, Sertânia and Araripina. In these areas, 3 permanent plots were installed, representing the main types of land use: closed caatinga, open caatinga and herbaceous pasture. The plots were fenced to prevent the entry of animals, enabling plant regeneration. The samplings for the evaluations carried out in the present study took place after 2 years of implantation of the plots. The estimation of the total C and N stock of the soil was performed from 10 cm of the surface to 1 m of depth or impediment layer using undisturbed samples and the density of the soil was determined. Total organic C and N were determined in an HCN analyzer, the soil density was used to calculate the soil mass and then the amount of carbon in each layer. 1 kg of soil was also collected for physical-chemical analysis. To evaluate the activity of soil microbial biomass, samples were repeated in the dry and rainy seasons, being collected at six random points, at a depth of 0-20 cm. The C and N of the microbial biomass were determined by the irradiation method. Basal soil respiration levels were determined using the alkaline adsorption method. The RBS did not differ statistically between closed caatinga and herbaceous pasture, however it presented an increase of 12.5% in open caatinga in the dry period. Seasonality did not influence statistically between the different management systems. The C-BMS did not differ statistically between areas of open caatinga and areas of herbaceous pasture. In the dry period, the closed caatinga areas presented C-BMS 52% higher than the others. In the rainy season, there was a decrease in the levels of C-BMS in areas of open caatinga and herbaceous pasture, representing a loss of 36% and 37.6%, respectively, when compared to the rainy season. In this period, the closed caatinga presented C-BMS 72.7% higher than the open caatinga and herbaceous pasture. The N-BMS showed no statistical difference between the different managements and periods. The qCO2 was low in all managements. In the dry period there was no statistical difference between the management. In the wet period, the closed caatinga areas showed lower qCO2. Seasonality influenced only the herbaceous pasture, which showed a lower value in the dry period. We can conclude that in more preserved environments (closed caatinga) the biological attributes show less fluctuation between periods. And that after 3 years of animal exclusion, the herbaceous pasture is already behaving like open caatinga, showing that the Caatinga has the potential to, in a short time, reestablish its microbial community.

BANKING MEMBERS:
Presidente - 457.055.504-72 - ANA DOLORES SANTIAGO DE FREITAS - UFRPE
Externo à Instituição - PAULO IVAN FERNANDES JÚNIOR
Externo à Instituição - RÔMULO SIMÕES CEZAR MENEZES