Banca de DEFESA: CLAUNITA NOVAIS ALVES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : CLAUNITA NOVAIS ALVES
DATE: 30/11/2023
TIME: 14:00
LOCAL: Sala virtual: meet.google.com/hte-ziwz-zva
TITLE:

Decomposition rate of cover crops and soil microbial biomass in a full sun and agroforestry cocoa cultivation system

KEY WORDS:

Cocoa cultivation systems, soil cover, microbial indicators, land use change

PAGES: 70
BIG AREA: Outra
AREA: Ciências Ambientais
SUMMARY:

Cover crops are used in agricultural systems to increase organic matter content, nutrient cycling, and soil conservation. The study was conducted to evaluate the production of biomass, nutrient accumulation, decomposition rate of cover crops, and soil microbial biomass in monoculture cocoa and agroforestry systems. The experiment was carried out at Ceplac (Executive Commission of the Cocoa Farming Plan) in Ilhéus, BA. The experimental design was a randomized block design with a 3x4 factorial scheme, consisting of three treatments and four decomposition times, with four replications. The treatments consisted of three ground cover plants: 1) pigeon pea, 2) brachiaria grass, and 3) spontaneous vegetation. The decomposition rate was evaluated using litter bags. Dry mass and nutrient accumulation by the cover crops were determined. For the evaluation of soil microbial biomass, a comparison was made between the monoculture system with four treatments (1) grasses, (2) legumes, (3) spontaneous plants, and (4) bare soil, and the agroforestry system (cocoa + erythrina). Carbon and nitrogen of the microbial biomass, soil microbial activity, soil organic carbon, labile carbon, and total nitrogen were analyzed. Metabolic quotient and microbial quotient were calculated. The average dry mass production among the treatments was 10 Mg ha-1. The spontaneous vegetation and brachiaria treatments showed the highest accumulation of potassium. The highest decomposition rate occurred for spontaneous vegetation and brachiaria grass. Pigeon pea had the slowest decomposition rate, remaining on the soil for a longer time. The agroforestry system with cocoa cultivation showed higher values of microbial carbon, total nitrogen, soil organic carbon, labile carbon, and metabolic quotient compared to the monoculture system. Cocoa trees in monoculture system intercropped with legumes showed similar microbial biomass results to the agroforestry system. The study demonstrated that converting the agroforestry system to monoculture reduced soil microbial biomass. However, the use of legume cover crops has the potential to increase soil microbial biomass in the cocoa monoculture system, similar to the agroforestry system.

COMMITTEE MEMBERS:
Presidente - 1099329 - JOAO CARLOS MEDEIROS
Interna - 1126298 - JAQUELINE DALLA ROSA
Externo ao Programa - 1720621 - CARLOS EDUARDO PEREIRA - UFSBExterno à Instituição - EDUARDO GROSS
Externo à Instituição - PAULO CESAR LIMA MARROCOS - UESC-BA
Externa à Instituição - RAFAELA SIMÃO ABRAHÃO NÓBREGA - UFRB