A utilização de polímeros hidroretentores a nível de semiárido se constitui em uma prática recente que vem ganhando cada vez mais espaço na agricultura. A partir do exposto, o presente trabalho teve por objetivo avaliar a influência de diferentes turnos de rega e polímero hidroretentor na qualidade de frutos de melancia cultivada em condições semiáridas. O experimento foi conduzido na Universidade do Estado da Bahia em Euclides da Cunha – Bahia. O delineamento estatístico foi de blocos casualizados. Os tratamentos consistiram na adoção de três turnos de rega, sendo: 1D – diariamente; 2D – a cada 1 dia; 3D – a cada 2 dias. As variáveis analisadas foram: número de frutos (NF) e peso de frutos (PF). Com auxílio do software Sisvar® foi realizada a análise de variância (ANOVA) e as médias foram comparadas pelo teste Tukey ao nível de 5% de probabilidade. O polímero hidroretentor influenciou de forma significativa as variáveis, sendo responsável pelo maior número de frutos (1,83) e maior peso de frutos (9,14 kg). A partir dos resultados obtidos, observou-se a eficiência do polímero hidroretentor na produção de melancia no semiárido.

The tomato seedling is one of the main inputs in the production process, and its quality is a strategic factor, making agriculture more competitive. It is possible to produce seedlings of exceptional quality using humic substances extracted from organic compounds, through the composting process. The humic acids present in humic substances play an important role in the release of nutrients, such as N, P, K, improvement of the chemical properties of the soil, elevation of the root system. In this scope, the disposal of organic waste for the composting process can be an economically sustainable alternative. From this, the objective of the research was to test the production of tomato seedlings through the application of humic acids and fulvic acids from the process of composting organic waste. The study was carried out at the State University of Bahia - UNEB, in Euclides da Cunha - BA, using a commercial cultivar. The materials used in the composting process were: coconut fiber, quixabeira soil, cattle manure and humus. Morphophysiological characteristics such as seedling height, stem diameter, chlorophyll content, root length, root volume, fresh and dry mass of tomato roots were evaluated in a completely randomized design with 3 compounds and 5 doses, totaling 15 treatments and 5 repetitions for each compound dose, with a 3x5 factorial scheme. The doses used were 0.0; 0.5; 1.0; 2.0 and 4.0 mL plant^-1. Based on the main results, it was possible to conclude that the dose of 0.5 mL plant^-1 allowed greater root volume (0.70 cm³), root fresh mass (0.46 g), root dry mass (0.27 g), root length (15.2 cm), seedling height (18.4 cm), stem diameter (0.50 mm), and chlorophyll content (44.5 ug cm^-2), in relation to other doses, being, therefore, recommended for root growth of tomato seedlings in semi-arid conditions.

The current agricultural scenario faces diverse challenges, among which phytosanitary issues are crucial. Plant diseases are mostly treated with chemicals, which cause environmental pollution and pathogen resistance. In light of the UN Sustainable Development Goals (SDGs), the biochar alternative use to chemical inputs fits into at least six of the proposed goals (2, 3, 7, 13, 15, and 17), highlighting the 12th, which explains responsible consumption and production. Biochar is valuable for inducing systemic resistance in plants because it is a practical and frequently used resource for improving physical, chemical, and biological soil attributes. This review assessed the beneficial and potential effects of applying biochar to agricultural soils on bacterial pathogen management. Such application is a recent strategy; therefore, this research evaluated 20 studies that used biochar to manage plant diseases caused by pathogens inhabiting the soil in different systems. The effectiveness of biochar application in controlling plant diseases has been attributed to its alkaline pH, which contributes to the growth of beneficial microorganisms and increases nutrient availability, and its porous structure, which provides habitat and protection for soil microbiome development. Therefore, the combined effect of improvements on soil attributes through biochar application aids pathogen control. Biochar application helps manage plant diseases through different mechanisms, inducing plant resistance, increasing activities and abundance of beneficial microorganisms, and changing soil quality for nutrient availability and abiotic conditions.

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.