Ecossistemas de regiões semiáridas, como a Caatinga, estão sendo afetados pelas mudanças climáticas globais, causando alterações na evapotranspiração (ET) e nos fluxos de CO2. Desse modo, o trabalho objetivou quantificar os fluxos de CO2 e ET, com o intuito de observar se a Caatinga atua como fonte ou como sumidouro de CO2. As medidas foram realizadas numa área de Caatinga, durante um período de 13 meses, no município de São João/PE, utilizando-se a metodologia da correlação dos turbilhões, com um analisador de CO2 e H2O e um anemômetro sônico tridimensional. Além disso, foi medida a umidade do solo nas profundidades de 10 a 50 cm. A ET variou de 0,4 a 4,7 mm d-1, com uma média de 2,33 mm d-1 e total de 933 mm. A ET também seguiu as variações da precipitação pluvial, com os valores mais elevados no período úmido e os menores, no período seco, possivelmente devido à baixa capacidade de retenção de água no solo. A variação do fluxo de CO2 na Caatinga indicou que a vegetação atuou ora como fonte e ora como sumidouro de carbono, com valores variando entre -4,89 e 6,87 μmol m-2 s-1. Entretanto, a Caatinga atuou, de maneira geral, como sumidouro de CO2, sequestrando, em média, 4,44 t C ha-1 ano-1. Desse modo, pode-se concluir que, nas condições edafoclimáticas do agreste pernambucano, a Caatinga atua sequestrando CO2 atmosférico, reforçando ainda mais a necessidade de preservação desse ecossistema.Palavras-chave: Caatinga; evapotranspiração; carbono; umidade do solo. Land Use Changes and Effects on the Water Balance Components in Agreste Pernambucano A B S T R A C TEcosystems in semi-arid regions, such as the Caatinga, are being affected by climate change, causing changes in evapotranspiration (ET) and CO2 fluxes. Thus, the work aimed to quantify the CO2 fluxes and ET, in order to observe whether the Caatinga acts as a source or a sink of CO2. The measurements were carried out in an area of Caatinga, during a period of 13 months, in the municipality of São João/PE, using the methodology of eddy covariance, with a CO2 and H2O analyzer and a three-dimensional sonic anemometer. In addition, soil moisture was measured at depths of 10 to 50 cm. The ET ranged from 0.4 to 4.7 mm d-1, with a mean of 2.3 mm d-1 and a total of 933 mm. The ET also followed the variations in rainfall, with the highest values in the wet season and the lowest in the dry season, possibly due to the low water retention capacity in the soil. The variation of the CO2 flux in the Caatinga indicated that the vegetation acted either as a source or as a sink of carbon, with values varying between -4.89 and 6.87 μmol m-2 s-1, being that the Caatinga acted, in general, as a CO2 sink, sequestering, on average, 4.44 t C ha-1 year-1. Thus, it can be concluded that, in the edaphoclimatic conditions of the Agreste of Pernambuco, the Caatinga acts by sequestering atmospheric CO2, further reinforcing the need to preserve this ecosystem.Key words: Caatinga; evapotranspiration; carbon; soil water content.

Cultura (ETc), que pode ser determinada pelo coeficiente de cultivo (Kc) e pela evapotranspiração de referência (ETo). Desse modo, o presente trabalho teve como objetivo determinar a ETc, o Kc e a eficiência no uso de água (EUA) de variedades de uva viníferas (Vitis vinifera), no Agreste Pernambucano. Foram estudadas três variedades de uvas quais sejam: Cabernet Sauvignon, Malbec e Muscat Petit Grain. A ETc foi determinada pelo método do balanço hídrico no solo e a ETo pelo método de Penman-Monteith. O Kc foi obtido pela relação entre ETc e ETo, sendo a EUA obtida pela relação entre produtividade e ET. Verificou-se que as temperaturas médias são consideradas ideais para a produção de uva na região e a umidade do solo não foi um fator limitante para o desenvolvimento da cultura. A ETc total no ciclo produtivo foi 354,0; 335,3 e 329,4 mm, para as variedades Cabernet Sauvignon, Malbec e Muscat Petit Grain, respectivamente. O Kc médio variou de 0,69 a 0,73. A EUA variou entre as variedades de uva, sendo de 0,54; 1,86 e 1,50 kg m-3, para Cabernet Sauvignon, Malbec e Muscat Petit Grain.Palavras-chave: Consumo hídrico; umidade do solo; vinhedo. Evapotranspiration, crop coefficient and water use efficiency of wine grapes cropped in Agreste PernambucanoA B S T R A C TIn viticulture, adequate water management is essential, which is obtained by knowing the crop evapotranspiration (ETc), which can be determined by the crop coefficient (Kc) and the reference evapotranspiration (ETo). Thus, the present work aimed to determine ETc, Kc and water use efficiency (WUE) of wine grapevine varieties (Vitis vinifera), in Agreste Pernambucano. Three grape varieties were studied, namely: Cabernet Sauvignon, Malbec and Muscat Petit Grain. ETc was determined by the soil water balance method and ETo by the Penman-Monteith method. Kc was obtained from the relationship between ETc and ETo, and the WUE was obtained from the relationship between productivity and ET. It was found that the average temperatures are considered ideal for grape production in the region and soil moisture was not a limiting factor for the development of the culture. The total ETc in the production cycle was 354.0, 335.3 and 329.4 mm, for the Cabernet Sauvignon, Malbec and Muscat Petit Grain varieties, respectively. The mean Kc ranged from 0.69 to 0.73. The EUA varied among the grape varieties, being 0.54, 1.86 and 1.50 kg m-3, for Cabernet Sauvignon, Malbec and Muscat Petit Grain.Key words: Water consumption; soil water content; grapevine.

Biochar application has been proposed as a promising strategy to improve soil functioning, defined as the integrated regulation of water storage, nutrient availability, and biological activity influencing crop productivity and crop performance in water-limited environments. However, its effectiveness depends on soil properties, climatic variability, and dominant processes. This study evaluated the effects of sewage sludge biochar on soil quality, water dynamics, nutrient availability, and bean productivity in sandy soil under rainfed semiarid conditions across two contrasting cropping cycles. A soil quality index (SQI) based on a minimum data set (MDS) derived from principal component analysis (PCA) was used to identify the dominant processes controlling soil functioning under different hydrological regimes. The two cropping cycles corresponded to wetter (Cycle I) and drier (Cycle II) hydrological conditions within the same agricultural year. Biochar application increased soil organic carbon and nitrogen stocks, enhanced phosphorus availability, and improved soil water storage. Despite similar evapotranspiration among treatments, water productivity increased, indicating more efficient conversion of stored soil water into yield. Biological indicators were more responsive during the wetter cycle, whereas physicochemical indicators dominated under drier conditions, revealing a shift in the processes regulating soil functioning. The minimum data set varied between cycles, demonstrating the environmental dependency of the SQI components. Overall, biochar improved soil resilience by enhancing nutrient retention and buffering crop response to water limitation, and the integrative SQI approach effectively captured these functional changes.

O estudo foi conduzido para investigar as propriedades de biochars produzidos a partir de diferentes materiais, com foco na capacidade de adsorção e dessorção de fosfato, elemento decisivo para a gestão eficiente do fósforo em solos agrícolas. Foram analisados três tipos de biochar: lodo de esgoto, cama de frango e madeira de cajueiro. A composição mineralógica dos biochars foi determinada por difração de raios X. A capacidade de adsorção e dessorção de fosfato foi avaliada utilizando as isotermas de Langmuir e Freundlich, e as quantificações do fosfato adsorvido e dessorvido foram realizadas por meio de centrifugação e análises colorimétricas. O biochar de madeira de cajueiro apresentou a maior área superficial específica e eficácia na retenção de fosfato, seguido pelo biochar de lodo de esgoto, sendo o biochar de cama de frango o menos eficiente. As curvas de dessorção indicaram uma liberação lenta de fosfato, sugerindo que parte do fosfato adsorvido foi retida pelos biochars e se tornou menos disponível para liberação. O biochar de madeira de cajueiro foi o mais eficaz na retenção de fósforo entre os biochars estudados. A adsorção de fosfato pelos biochars seguiu uma tendência dependente da concentração, destacando a importância da caracterização mineralógica na avaliação da reatividade química e da capacidade de adsorção dos biochars.

Soil degradation and water scarcity pose major challenges to sustainable agriculture in semiarid regions, requiring innovative strategies to enhance water use efficiency (WUE) and soil fertility. This study assessed the effects of sewage sludge biochar (SSB) on soil properties, WUE, and common bean yield through a small-scale controlled field experiment under rainfed conditions in Northeast Brazil. Four SSB application rates (5, 10, 20, and 40 t ha⁻¹) were compared with conventional NPK fertilization, treated sewage sludge (SS), and chicken manure (CM). The application of 20 t ha⁻¹ (B20) significantly improved soil organic carbon, nitrogen content, water retention, and microbial biomass. B20 also increased WUE by 148% and grain yield by 146% relative to NPK, while maintaining safe levels of potentially toxic elements (PTE) in bean grains. Although 40 t ha⁻¹ (B40) enhanced soil fertility further, it posed a risk of PTE accumulation, reinforcing the advantage of B20 as an optimal and safe dose. These results highlight the potential of SSB to replace or complement conventional fertilizers, especially in sandy soils with limited water retention. The study supports SSB application as a sustainable soil management practice that aligns with circular economy principles, offering a viable solution for improving productivity and environmental resilience in semiarid agriculture.

Nowadays, the development of low-cost technologies that help the rural producer in raising the productivity of crops with environmental concern is essential. From this, the objective of the present work was to evaluate doses of humic substances as an alternative for the production of squash seedlings. The research was developed at the University of the State of Bahia - UNEB, in Euclides da Cunha - Bahia, using the Moranga Exposure cultivar. The experimental design adopted was completely randomized with 3 compounds and 5 doses, with 15 treatments and 5 repetitions for each compound dose, in a 3x5 factorial scheme. The doses of humic substances used were 0, 0.5, 1.0, 2.0 and 4.0 mL/plant^-1. The following variables were analyzed: number of leaves, stem diameter, plant height, chlorophyll content, root length, shoot dry mass and root dry mass. Based on the results found, it was concluded that the dose of 0.5 mL/plant^-1 provided squash seedlings with a greater number of leaves (3.4), plant height (25.2 cm), stem diameter (0.68 mm), chlorophyll content (40.1 µg.cm^-2), root length (31.40 cm), shoot dry mass (1.78 g), root dry mass (0.35 g). It was also possible to observe that the dose of 4.0 mL/plant-1 and the absence of humic substances in the dose of 0 mL/plant^-1 had a limiting effect on the development of the culture. Thus, doses of 0.5 mL/plant^-1 are indicated for the production of squash seedlings in the semi-arid region.