In this study, samples of honey produced in three different regional climates in the southwest Bahia, Brazil (semi-arid, Atlantic and Transitional Forest Zones) were characterized on the basis of their mineral and trace elements, ash content and electrical conductivity. The metals were determined by atomic absorption spectrophotometry. The cluster and principal component analysis (PCA) methods were applied to the chemical concentration data in order to study the chemistry variables capable of promoting a characterization of the honey produced in each area. Cluster analysis and PCA distinguishes the different groups of honey samples corresponding to each region of the three geographical origins. The high correlation between electrical conductivity and Cu observed in honey samples from transitional forest zones suggested a coupling to the nutrient cycle, and can be attributed to use of copper compounds in coffee production, a major activity developed in all transitional forest zones.

The objective of this work was to evaluate alternative sources of potassium for improving soil fertility and coffee productivity and beverage quality. The experiment was conducted in a coffee (Coffea arabica) crop, planted in an Oxisol area, in the municipality of Patrocínio, in the state of Minas Gerais, Brazil. The treatments consisted of the K sources TK47 and Super Greensand (SG) - both based on glauconite silicate mineral -, at the following doses: 0 kg ha^-1 K₂O (control); 42, 84, 168, and 336 kg ha^-1 K₂O from TK47; 618 kg ha^-1 K₂O from KCl; and 168 kg ha^-1 K₂O from SG. A randomized complete block design was used, with four replicates in each treatment. The experimental units consisted of three rows with ten plants each, using the eight central plants as the useful plot. Potassium fertilization with TK47 increased soil fertility, correcting soil acidity and elevating K⁺, P, and Ca²⁺ contents, effective cation exchange capacity, and Zn²⁺ and Fe²⁺ levels in the soil. Fertilization with 336 kg ha^-1 K₂O from TK47, in a single dose, provides grain yield and polyphenol oxidase activity similar to those of fertilization with 618 kg ha^-1 K₂O from KCl, in a split-dose, but a better sensory analysis of the resultant beverage.

O objetivo deste trabalho foi avaliar os efeitos da adubação sobre os teores de P e K, em solo com fertilidade construída, e identificar as doses de N, P e K necessárias para obtenção de maior rentabilidade com a rotação entre soja e milho nesses solos. O experimento foi realizado durante três safras, em propriedade com alto investimento tecnológico, em Latossolo Vermelho-Amarelo argiloso de Cerrado, com elevada fertilidade. Utilizou-se o delineamento de blocos ao acaso, com parcelas subdividas e três repetições. Os tratamentos consistiram de 0, 50, 100 e 150% das doses de fertilizantes NPK recomendadas na semeadura (parcelas) e das doses de KCl (soja) e N (milho) em cobertura (subparcelas). Mesmo após a colheita das três safras, os teores de P (Mehlich-1) se mantiveram inalterados no solo sem adubação. Além disso, não houve decréscimo na produtividade da soja na ausência de adubação. O milho, no entanto, foi mais sensível à redução de adubação, com o máximo retorno econômico obtido com 312 kg ha^-1 do adubo formulado 10-32-10, e 263 kg ha^-1 de ureia em cobertura. Solos com fertilidade construída demandam ajustes de manejo de adubação, para o uso eficiente dos fertilizantes em lavouras com alto investimento tecnológico.

In this study honey samples produced in the southwest of Bahia were characterized based on physicochemical and mineral (Ca, Mg, Na, K, Mn, Fe and Zn) composition. The metals were determined by atomic absorption spectrophotometry. The application of multivariate analysis showed that the honey colors are consequence of the mineral and physicochemical compositions. The darkest honey samples are characterized by higher values of pH and for presenting a strong relationship with Ca and Fe content

The use of cover crops is an important strategy for soil management in the Brazilian Cerrado to improve no-tillage (NT) systems. For this, it is necessary know the potential of cover crop species for biomass production, nutrient cycling, and persistence of residues on the soil surface in soils and climatic conditions of this biome. Thus, the experiment was developed to evaluate the agronomic potential of cover crops cultivated on an Oxisol (Latossolo Amarelo) in the Cerrado of Piauí, Brazil. The experiment was conducted from January 2015 to July 2016. The experimental design was in randomized blocks with 11 treatments and four replicates. The treatments consisted of single and intercropped cover species. The evaluations were: dry mass production, nutritional composition of the plants, nutrient accumulation by dry mass produced and decomposition rate of the dry mass produced for each treatment. The higher dry matter production was obtained with Crotalaria juncea, Cajanus cajan (cv. IAC-Fava larga), Pennisetum glaucum and Brachiaria ruziziensis. The lower dry matter production was obtained with Mucuna aterrima, and mix of Crotalaria spectabilis + Pennisetum glaucum. The higher nutrients accumulation in the plants occurred for Cajanus cajan (cv. IAC-Fava larga), Crotalaria juncea and Crotalaria spectabilis. The cover plants studied presented good potential for soil conservation, due to the permanence of residues on the surface, except for Mucuna aterrima and Crotalaria spectabilis.

Soil organic carbon (SOC) plays a critical role in the sustainability of grazingland ecosystems around the world. However, maintaining or increasing SOC levels remains a major challenge, particularly in subtropical regions where coarse-textured soils predominate. This study evaluated the long-term (>20 years) impacts of grazingland intensification (conversion of native rangelands into more intensively managed silvopasture and sown pasture) on SOC and nitrogen (N) responses in particle size/density fractions. Treatments consisted of field replicated (n = 2) experimental sites that represented a gradient of intensification ranging from native rangelands (low intensification), pine (Pinus spp.)-bahiagrass (Paspalum notatum) silvopasture (moderate intensification), and bahiagrass pastures (high intensification). Soil organic C and N increased in response to the conversion of native rangelands into more intensively managed grazinglands, but no difference was observed in total SOC and N between silvopasture and sown pasture. Despite the positive impact of intensification on SOC and N pools, accumulation occurred primarily in more labile fractions. For instance, at the 0 to 10 cm depth, light-free C (LF-C) increased from 12.9 g kg⁻¹ soil in the native rangeland to 24.7 g kg⁻¹ soil in the sown pasture. Largest differences between the ecosystems were observed at the 10 to 20 cm depth where LF-C increased by as much as 170% following the conversion from native rangelands to sown pasture. Similar responses were also observed for N. Grazingland intensification showed no effect on soil aggregation, but SOC and N associated with macroaggregates (2,000 to 250 μm) increased with intensification. Results indicate that grazingland intensification promoted SOC and N accumulation, primarily through an increase in the LF fraction.