Emicleiton Duarte De Abreu

Biochar comes from organic biomass and is used to improve agricultural productivity. However, its variable chemical composition limits its classification and effective use. Thus, the objective of this study was to characterize the nutrient contents and properties of different biochars produced in the southern Agreste region of Pernambuco. The research was developed at the Federal University of Agreste de Pernambuco (UFAPE), where biochars are produced from sewage sludge (B1), grape fermentation (B2), cashew wood (B3), chicken litter (B4) and beans (B5) via a slow pyrolysis process. Standard Embrapa and Iac methodologies were followed in the chemical analyses. Principal component analysis (PCA) was used to identify specific characteristics that made them suitable for use in different soil types. PCA revealed that the first four main components (PC1, PC2, PC3 and PC4) explained 100% of the total data variability. PC1 was defined by variables such as C, H and pH. PC2 was positively correlated with nutrient content and CEC. PC3 and PC4 were positively correlated with K, N, P and Mg. On this basis, the use of B1 is indicated for soils with high levels of organic matter, B2 is indicated for soils deficient in elements such as N and K, B3 and B5 are indicated before its use, its association with other sources of nutrients is necessary, and B4 is recommended for soils poor in P and Ca.

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.