Banca de DEFESA: CAMILA EDUARDA SOUZA DE SOUSA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : CAMILA EDUARDA SOUZA DE SOUSA
DATE: 24/02/2022
TIME: 10:00
LOCAL: INSTITUTO DE ZOOTECNIA
TITLE:

Soil carbon and nitrogen stocks and dynamics in different land use systems

KEY WORDS:

Organic matter, organic carbon, carbon stock.

PAGES: 60
BIG AREA: Ciências Agrárias
AREA: Zootecnia
SUMMARY:

SOUSA, Camila Eduarda Souza de. Soil carbon and nitrogen stocks and dynamics in different land use systems. 2022. 54p. Dissertation (Master in Animal Science, Forage andPasture). Instituto de Zootecnia, Departamento de Nutrição e Pastagem,Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, 2022.  Soil can store high amounts of carbon resulting from biogeochemical processes, which take place through the decomposition of organic matter. Several types of agricultural production systems contribute to the increasing of carbon derived from organic matter in the soil, influencing the production of organic compounds of different chemical natures that promote the increase and diversification of the soil microbiota, bringing benefits to the production system. The assessment and diagnosis of soil management and use can be made through quality indicators such as microbiota and organic matter fractions, as these are sensitive to environmental changes. Therefore, we aimed to evaluate changes in the contents and stock of total organic carbon, labile carbon, soluble carbon, microbial biomass carbon, and total nitrogen in the soil from different land use systems in Barbacena-MG. The experiment was conducted in a completely randomized design, with five replications in each treatment. Four areas with varying soil use were selected, namely: native forest (FN), twenty-five-year-old grass-legume consortium (CGL), thirteen-year-old silvopastoral system (SSP), and 27-year-old pasture monoculture (MP). Samples were collected at depths of 0-5, 5-10, 10-20, and 20-30 cm through deformed and undisturbed soil to perform analyzes of soil bulk density, soil texture, carbon and total nitrogen, and organic matters fractions. The contents and stock of these elements and the soil carbon management index (CMI) were calculated. There were significant differences through the Kruskall-Wallis statistical test and Dunn's test (p>0.05) in all analyzed variables, except total nitrogen. Soil use and composition of the systems influenced the dynamics of organic matter and the accumulation of carbon in the soil. The pasture monoculture presented total organic carbon contents closer to the native forest, revealing a reduction of 33% compared to the reference treatment, followed by grass-legume intercropping with a difference of 42%, and the silvopastoral system with a 50% reduction. MP and CGL revealed lower labile carbon, soluble carbon, and lower microbial biomass carbon than the SSP treatment, whichwas closer to native forest. The carbon management index showed a result above 100 at all depths evaluated in the silvopastoral system; in MP, the index exceeded 100 only in the 5-10cm range, and the CGL system did not reach an index of 100 at any depth. Soil carbon stock under legume-grass and silvopastoral system showed similar values; they were statistically similar (p<0.05) and lower than MP and FN, which showed closer stocks. The soil under 13-year-old silvopastoral presented a similar carbon stockwith that soil under 27-year-old pasture monoculture, 25-year-old grass-legume consortium, and native forest. However, the organic matter fractions in SSP indicate the highest potential of this system to store carbon in the long term.

 

BANKING MEMBERS:
Externo à Instituição - HIRAN MARCELO SIQUEIRA DA SILVA
Externa à Instituição - ANA CLAUDIA RUGGIERI - UNESP
Presidente - 387749 - JOAO CARLOS DE CARVALHO ALMEIDA