Banca de DEFESA: ARTHUR GUILHERME DO NASCIMENTO SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ARTHUR GUILHERME DO NASCIMENTO SANTOS
DATE: 26/02/2026
TIME: 09:00
LOCAL: UFRPE
TITLE:

Wastewater as a sustainable strategy for water supply in agriculture in the semiarid region of Pernambuco: Impacts on carbon compartments and forage productivity

KEY WORDS:

Wastewater; organic carbon; aggregate stability.

PAGES: 58
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Manejo e Conservação do Solo
SUMMARY:

The Brazilian semiarid region faces significant challenges for agricultural production due to its climatic particularities, such as prolonged drought periods and irregular rainfall distribution. However, these factors are not the only drivers of limitations to socioeconomic development, as inadequate land use, inefficient management systems, and low soil organic matter (SOM) contents also play an important role. This scenario requires the adoption of integrated and sustainable strategies, such as the use of non-conventional water resources associated with the cultivation of species adapted to the region, in line with low-carbon agriculture. In this context, the present study aimed to evaluate improvements in soil quality following the application of treated wastewater under different techniques, associated with the use of a regionally relevant species in the semiarid region of Pernambuco. The experiment was conducted in the municipality of Caruaru, in the Agreste region of Pernambuco, in an area belonging to the Rendeiras Wastewater Treatment Plant, managed by the Pernambuco Sanitation Company (COMPESA), using a randomized block design with four replicates. The treatments consisted of the application of three types of water, chlorinated effluent (CE), treated effluent (TE), and treated water (TW), for irrigation of forage cactus (Opuntia stricta), cultivated in 3.0 × 5.0 m plots, with a native Caatinga vegetation area (NV) with similar characteristics used as a reference. The use of treated effluent increased fresh biomass yield of forage cactus by 63,6% and 78,5% (t ha-1) compared with chlorinated effluent and treated water, respectively. Soil physical and chemical characterization was based on the collection of disturbed and undisturbed samples at the 0–10 and 10–20 cm layers, evaluating pH, exchangeable cations, bulk density, and particle size distribution. Regarding soil carbon compartments, the fractions of soil organic carbon (SOC), particulate organic carbon (POC), mineral-associated organic carbon (MAOC), hot-water extractable carbon (HWEC), and permanganate-oxidizable carbon (C-POX) were quantified, as well as the calculation of carbon stocks for each fraction. Structural stability was assessed by the distribution of macroaggregate classes (small, large, and extra-large) and by the indices of proportional aggregate mass (PAM), macroaggregate class mass (MAC), mean weight diameter (MWD), geometric mean diameter (GMD), and aggregate stability index (ASI). SOC contents and stocks were also determined within the three macroaggregate classes. The results indicated that wastewater reuse promoted expressive improvements in soil structural quality and soil carbon dynamics. Aggregate stability index values in TE and CE were close to those observed under native vegetation, ranging from 88% to 89% in the 0–20 cm profile. The proportion of extra-large macroaggregates was high in the irrigated systems, reaching 71,1% under TE and 72,7% under CE, values higher than those observed in native vegetation, which reached 62,7%. Total carbon stocks ranged from 46,95 to 60,64 Mg ha-1 in the irrigated systems and approached those observed under native vegetation, which reached 89,06 Mg ha-1. In the extra-large macroaggregate class, considered the main physical protection compartment, carbon stocks reached 69,45 Mg ha-1 under TE and 44,98 Mg ha-1 under CE, while native vegetation reached 77,53 Mg ha-1. These results highlight the potential of wastewater reuse to increase carbon stocks, enhance forage cactus productivity, promote the formation of stable aggregates, and recover soil structural quality in the semiarid region, in line with water reuse policies and the United Nations Sustainable Development Goals.

COMMITTEE MEMBERS:
Presidente - ADEMIR DE OLIVEIRA FERREIRA
Interno - ***.952.028-** - FELIPE JOSÉ CURY FRACETTO - USP
Externo ao Programa - 383815 - ABELARDO ANTONIO DE ASSUNCAO MONTENEGRO - UFRPE