Banca de QUALIFICAÇÃO: TIAGO PAULA DA SILVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : TIAGO PAULA DA SILVA
DATE: 09/06/2023
TIME: 09:00
LOCAL: Sala 24 do Departamento de Solos
TITLE:

Soil aggregates as quality indicators in organic farming areas in sandy soils of the Baixada Fluminense, RJ

KEY WORDS:

Soil management, conservation systems, edaphic indicators, bacterial diversity

PAGES: 85
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Manejo e Conservação do Solo
SUMMARY:

In the Baixada Fluminense, soils with a sandier texture and low levels of organic carbon in the surface layer are predominant. These areas are commonly cultivated with conventional methods, promoting the intensification of soil degradation, decreasing its productive capacity. The use of conservationist practices is necessary to minimize these impacts, in order to improve productivity and soil quality. One of the practices that can be used is the organic cultivation system associated with the no-till farming system (NT), and some indicators are used to verify the quality of the soil; aggregation is one of these important indicators. The present study was divided into two chapters, in chapter I (2021) - the objective was to evaluate the influence of different management systems and vegetation cover on the pathways of aggregate formation (biogenic and physiogenic), in addition to evaluating the influence of these attributes on fertility levels and organic carbon contents, and their fractions. In the second (2022), bacterial diversity was additionally evaluated.  The study was conducted in the organic production unit Sítio do Sol, in the region of Baixada Fluminense - RJ. The experimental design in both chapters was 3x2x2, with three repetitions, in which two management systems were evaluated, no-tillage system (NT) and conventional system (CT). The mulches in chapter I were different in each chapter, in the first one three mulches were evaluated, namely; C1: cocktail 1 - (crotalaria - Crotalaria juncea (20 kg ha^-1, Jack Bean - Canavalia ensiformis - 150 kg ha^-1 and millet - Pennisetum glaucum - 60 kg ha^-1), C2: cocktail 2 (with 50% of the number of seeds used in C1), and P.E: spontaneous plants. While in chapter II, form C2: cocktail 2 (with 50% of the number of seeds used in C1), M: Millet (Pennisetum glaucum - 60 kg ha^-1), and CJ: Crotalaria (Crotalaria juncea - 40 kg ha^-1). Undisturbed samples of 0-5 and 5-10 cm were randomly collected in Chapter I, while in Chapter II undisturbed samples of 0-10 cm were taken from the crop row. From these samples, aggregates with diameters between 9.7 and 8.0 mm were classified according to the formation route (biogenic or physicogenic). From these, the chemical attributes (pH, Ca²⁺, Mg²⁺, Al³⁺, P, Na⁺, K⁺) and also the carbon fractions (total organic carbon - TOC, mineral-associated organic carbon - MAOC, particulate organic carbon - POC, and free light fraction carbon - FFC) were quantified, in both chapters. In chapter II, bacterial characterization was also performed, from samples, regarding richness and diversity. Chapter I concluded that from 0-5 cm there is a higher proportion of biogenic aggregates, without influence of the different management and cover systems. SC is associated with higher levels of soil fertility. In Chapter II, the proportion of biogenic aggregates was higher than physiogenic aggregates at 0-10 cm depth, without significant influence of the different management systems and covers. The fertility levels are higher in the CT, there was no statistical difference between the formation paths and different mulches. The M cover is associated with higher POC values and lower MAOC values. The management system influenced the bacterial richness and diversity, being the highest abundance connected to NT.

COMMITTEE MEMBERS:
Presidente - 1060711 - MARCOS GERVASIO PEREIRA
Externo ao Programa - 2136627 - NIVALDO SCHULTZ - UFRRJExterna à Instituição - ELIANE MARIA RIBEIRO DA SILVA - EMBRAPA