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Biofilm obtained from Bacillus subtilis subsp. spizizenii inoculated on vegetable seeds has been shown to have plant growth-promoting capacity. Seed inoculation with biofilm produced by this strain could also reduce the adverse effects on plant growth caused by soil or substrate heavy metal overabundance. Therefore, the objective of this work was to evaluate the impact of biofilm inoculated on tomato (Solanum lycopersicum L.) seeds, which were planted on a substrate with artificially added zinc. First, seeds of the Río Grande tomato variety were exposed to increasing zinc concentrations, namely: 50, 100, 200, and 400 ppm, with and without bacterial biofilm inoculation. Zinc addition and seed inoculation affected germination parameters. For example, an extra 200 and 400 ppm of zinc led to high toxicity. Biofilm inoculation, however, reduced the noxious effects of excess zinc, bringing acute toxicity down to moderate. Then, tomato plants growing from inoculated and non-inoculated seeds were cropped for 4 months in both substrates with 400 ppm zinc and without added zinc. Extra zinc addition significantly (p < 0.05) reduced tomato root and shoot biomass, plant height, and fruit number at harvest time. However, seed biofilm inoculation avoided the harmful effect of zinc on plant growth parameters, fruit yield, and fruit quality. The roots and shoots of plants growing on contaminated substrates showed very noticeable increases in zinc levels compared to the control, while fruits only showed a much weaker zinc gain, even if this was significant (p < 0.05). Moreover, root shoot and fruit concentrations of elements other than zinc, (nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper, lead, and cadmium) were not or only weakly affected by the addition of this metal to the substrate. In summary, the biofilm of B. subtilis proved to be effective as a bioinoculant to alleviate negative effects on tomatoes cropped in a substrate with excess zinc.

Limited knowledge is available regarding biochar (BC) obtained from beach-cast seaweed, which needs to be characterized to better prospect its potential applications. Beach-cast seaweed BCs were produced at two temperatures (300 and 600 °C) and two residence times (1 and 3 h). First, an extensive characterization of feedstock and their derived BCs was performed. Then, an incubation experiment was conducted to investigate the potential of these BCs as ameliorants in two acidic soils, classified as Umbrisols. Proximate and elemental analyses suggested the presence of more stable C structures in BCs at 600 °C with a high C, fixed carbon (FC) and low H, O and volatile matter (VM); additionally, thermogravimetric graphics showed less weight loss. Some features from the raw material were present in biochars obtained at 300 °C but absent at 600 °C. Dissolved organic carbon was much lower in BCs pyrolyzed at 600 °C than at 300 °C, suggesting the higher aromaticity of the former, allowing more resistance to water extraction. The breakdown of proteinaceous soluble materials after pyrolysis was revealed by fluorescence. Residence time caused minor effects in biochar properties compared to temperature. The soil pH and macronutrient availability of the two studied soils increased after beach-cast seaweed biochar addition.

Biochar (BC), which can be produced from several feedstocks, has been widely studied. However, the BC derived from highly pyrolytic shrubs, such as broom and gorse, has been less frequently used and only partially characterized. These wastes, when used for the preparation of biochar, can fix carbon and contribute to environmental conservation, helping to achieve sustainable development objectives. Eight biochars from broom and gorse were produced and fully analyzed, providing a more complete and novel description, with new insights for assessing their utilization. The aims of this study were to elucidate the effects of feedstock, pyrolysis temperature, and residence time on biochar properties and to assess the adequacy of these biochars as fuel. Elemental and proximate analyses and estimations of the lower and higher heating values were performed, and physical and chemical properties, as well as several other related energy indices, were determined. The experimental results showed that the temperature was a key factor in the properties of the biochars, while residence time was less important. The BCs obtained from the two feedstocks did not show important effects on the properties, which is consistent with the fact that they are woody legumes. These biochars had a high carbon content and were thermally stable. The BCs also had a high calorific value and suitable energetic properties. Additionally, their PAH contents were low, indicating that the use of these biochars would be safe. In conclusion, broom- and gorse-derived biochars can be considered as renewable fuels for green energy production.

Olive groves rank among the cropping systems facing higher erosion risk in Mediterranean Europe. The adoption of erosion control soil management practices is key for reducing such risk and driving olive production towards sustainability. This field experimental study aimed to quantify the erosion control performance of improved soil management as compared to conventional soil management in olive groves of NE Portugal. The design aimed to compare the effects of introducing no-tillage (NT) to a conventionally managed (T) olive grove and those with complementing ground cover by adventitious species (NS) with a sown cover (S) and comprised four treatments: TNS (reference for conventional), TS, NTNS and NTS. Erosion microplots (4 m2) were installed (two per treatment), recording soil loss, runoff and ground cover in seven erosion events throughout one year. The best erosion control performance was found in NTNS (low-cost improved soil management treatment) with 50% and 85% reductions in soil loss, respectively, in the annual total and in erosion events following large precipitation periods. Plots with adventitious vegetation ground cover performed better in soil loss control than the sown ones. Converting to no-tillage, as compared to sowing herbaceous vegetation to increase ground cover, proved more performant and less hazardous for improving erosion control in olive groves.

ABSTRACT Various attributes are often required to build soil quality indicators. However, determining these attributes is time-consuming and requires several specific devices. Thus, it is desirable to develop indexes that express soil quality based on easily determined attributes. The objective of this study was to investigate the spatial variability of the S index and its correlation with other physical and chemical soil attributes to generate a pedotransfer function for estimating the S index. A georeferenced sampling mesh covering 1.4 ha and employing 71 points was installed. The soil samples were collected in 0.00–0.15 m and 0.15–0.30 m deep layers to determine the physical and chemical attributes. The results indicated that the S index was correlated with porosity, carbon stocks, cation exchange capacity, and particle size fractions. However, macroporosity, microporosity, and sand content were the most suitable attributes for the construction of pedotransfer functions. A principal component analysis indicated that the S index was representative of 9.4% and 11.5% of the total variability in the dataset in the respective soil layers. Spherical semivariogram models showed that the S index was spatially dependent and ranged between 84–188 m. The S index maps estimated by the pedotransfer function resemble the observed S values; therefore, the function can be applied in spatial variability studies.

Se planteó una investigación empírica con los objetivos de conformar un conjunto de indicadores de sostenibilidad económicos y sociales para comparar con el Índice de Sostenibilidad (IS) entre los tipos de Cacao Nacional y Cacao CCN51. Los indicadores fueron producto de una revisión de la literatura, para estructura una encuesta a 73 agricultores de la provincia El Oro (Ecuador). El proceso estadístico consistió en un análisis descriptivo y de componentes principales (ACP), para conformar indicadores que se clasificaron por dimensiones (económicas y sociales). El calculando del IS fue producto de la suma de los indicadores normalizados en una escala de 0 a 1 y promediados por dimensión. También se realizó una prueba t de muestras independientes por tipo de cacao, para determinar significancia al 5%. Los indicadores económicos evidenciaron mayor área neta con menor rendimiento del cacao Nacional con respecto al cacao CCN51. Los indicadores sociales filiación agraria y equidad obtuvieron mayor puntuación en el cacao Nacional. El ACP conformo tres componentes por tipo de cacao, lo que permitió seleccionar los 8 indicadores propuestos, sin obtener significancia en la dimensión económica. El IS fue de baja sostenibilidad para bajo en ambos tipos (Nacional= 45%; CCN51=41%), sin existir diferencias significativas (p=0,134). Abstrac Empirical research was proposed with the targets of forming a set of indicators of economic and social sustainability to compare with the Index of Sustainability (IS) between the types of National Cocoa and Cocoa CCN51. The indicators were a product of a review of the literature, to structure a survey of 73 farmers of the province of El Oro (Ecuador). The statistical process consisted of a descriptive analysis and main components (ACP), to produce indicators that were classified by dimensions (economic and social). The calculating of IS was a product of the sum of the standardized indicators on a scale of 0 to 1 and averaged by dimension. There was also a t-test for independent samples by type of cocoa. The economic indicators showed a higher net area with lower performance of national cocoa levels with regard to cocoa CCN51. The social indicators agrarian affiliation and equity obtained higher scores in the national cocoa. The ACP conformed three components by cocoa type, which allowed the selection of the 8 proposed indicators, without getting significant in the economic dimension. The IS was low sustainability for both types (National = 45%; CCN51 = 41%), without significant differences (P= 0,134).

Understanding hydrological processes controlling stream chemistry and quantifying solute concentrations over time is crucial for estimating future alterations of water quality due to land use or climate change impacts, as well as for setting preventive or remedial actions. In the current study, soluble sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+) concentrations and loads were assessed in waters from two small catchments located at different distances to the sea (9 km Valiñas and 30 km Abelar) in NW Spain from 2003 to 2016. Solute concentrations were determined using spectrometric techniques, while streamflow data were employed for estimating loads. Moreover, concentration-discharge relations were calculated for each solute and catchment. The average concentrations of soluble Na+, K+, Ca2+ and Mg2+ were, respectively, 16.5, 2.6, 7.9 and 4.1 mg L−1 in Valiñas, and 8.2, 0.9, 2.9 and 3.4 mg L−1 in Abelar, although variability among samplings was high. The four soluble ions showed a dilution pattern in Valiñas, whereas in Abelar Na+ tended to a chemostatic behavior and K+ and Ca2+ were positively related to streamflow. In conclusion, the dominant processes controlling these relationships are local and depend on catchment characteristics such as land use (including slurry applications in Abelar), distance to the sea, and vegetation cover.

El trabajo se realizó durante las campañas de siembra 2008-2009 y 2009-2010, en 12 localidades de la provincia de Holguín, en el cultivo de Vigna unguiculata L. Walp (fríjol caupí); con el objetivo de determinar los porcentajes de incidencia y distribución de Rhizoctonia solani Kühn, en cuatro variedades comerciales, 12 localidades y dos campañas de siembra. Los muestreos se llevaron a cabo en campos de 4ha por localidad, en 3 fases fenológicas del cultivo, aplicándose las Metodologías de Señalización y Pronóstico propuestas por el Instituto Nacional de Investigaciones de Sanidad Vegetal (INISAV, 1989). Para evaluar el patógeno se utilizó una escala de daño modificada propuesta por el Centro Internacional de Agricultura Tropical (CIAT, Colombia 1987) y las formulas de Townsend y Hauberger (1963). De los resultados obtenidos se infiere que los porcentajes de distribución y los índices de infección comenzaron a ser superiores a partir de los 30-40 días de establecido el cultivo, encontrándose sus mayores valores a los 60 días para todos los casos, las localidades que alcanzaron los mayores valores de incidencia y distribución del patógeno fueron Arroyo Seco, Boca, Cristino Naranjo y la Guanina y de las variedades evaluadas la var. Titán fue la que mostró mayor tolerancia al ataque del patógeno, seguida por la IITA- Precoz, mientras que la INIFAT-93 y la Carita tradicional fueron las más susceptibles

One of the most viable strategies to restore metal contaminated soils is the introduction of plants specialized in their accumulation or able to tolerate very high metal concentrations. This research evaluated: i. the maize as a Pb-accumulator plant; ii. the effects of EDTA-chelating agent for Pb-uptake by maize; iii. amending effect of EDTA on the soil Pb-availability using different extracts. Treatments consisted of Pb rates (100; 200; 350; 1,200 and 2,400 mg kg-1) applied to a Rhodic Hapludox in the form of Pb3(NO)2 with (0.5 g kg-1) and without EDTA. Lead concentrations were determined in maize plant shoots. Soil available Pb was obtained using DTPA, Mehlich-3 and saturation solutions methods. Ionic speciation in the soil solution was performed using the software Visual-Minteq. Although a low t value was found (t 1,500 mg kg-1 of Pb) in maize shoots regardless of EDTA addition. Maize plants treated with EDTA had lower dry matter yield, mainly due to toxic levels of Fe and Al of the Oxisol. All extracting solutions were effective to determine available Pb in soil samples, but the saturation extract is a more difficult and time consuming procedure. At low and medium Pb levels, the plants grew less on EDTA, therefore the phytoextration process was less efficient. The addition of EDTA to the soil is not recommended with the purpose of increasing Pb absorption by maize plants.Uma das estratégias mais viáveis para a descontaminação de solos é a introdução de plantas especializadas na acumulação ou que toleram altas concentrações de metais. Nesse estudo avaliaram-se: i. o potencial acumulador de Pb de plantas de milho; ii. os efeitos do EDTA na absorção de Pb pelo milho; iii. o efeito do EDTA na disponibilidade de Pb utilizando diferentes extratores. Os tratamentos consistiram em doses de Pb (100; 200; 350; 1.200 and 2.400 mg kg-1) aplicados em um Latossolo na forma de Pb3(NO)2 com (0.5 g kg-1) e sem EDTA. A concentração de Pb foi determinada na parte aérea das plantas de milho, e no solo determinou-se o Pb disponível pelos métodos DTPA, Mehlich-3 e pasta de saturação. A especiação iônica da solução do solo foi determinada utilizando-se o software Visual-Minteq. Embora tenha sido encontrado um baixo valor t (t 1.500 mg kg-1), independente da adição de EDTA. As plantas de milho que receberam EDTA apresentaram redução na massa seca, principalmente devido aos níveis tóxicos de Fe e Al do Latossolo. Todas as soluções extratoras utilizadas foram eficientes em determinar o Pb disponível nas amostras de solo, mas a pasta de saturação foi o processo mais trabalhoso. Em baixa e média concentração de Pb no solo as plantas cresceram menos com EDTA, portanto a fitoextração foi menos eficiente. Não é recomendada a adição de EDTA no solo buscando aumentar a absorção de Pb pelas plantas de milho.

The objective of this paper is to assess the changes in soil physical and chemical properties resulting from the conversion of native forest to pasture and pasture to secondary forest in the state of Santa Catarina, Brazil. Seven forest–pasture successional stages were identified using aerial photographs and satellite images acquired in 1957, 1978, and 2008. Successional stages were coded as FFF, FPF, PFF, PPF, FPP, FFP, and PPP, where the first, second, and third letters refer to the land uses (P, pasture; F, forest) practiced in 1957, 1978, and 2008, respectively. Soil samples were collected by layer at depths of 0–10, 10–20, 20–40, 40–60, 60–80, and 80–100 cm. Clay contents, soil bulk density (Db), macroporosity (MP), microporosity (mP), pH, Aluminum (Al), cation exchange capacity (CEC), calcium (Ca), potassium (K), phosphorus (P), total organic carbon (TOC) content, carbon stock, and δ13C abundance were quantified. Conversion of forest to pasture increased soil P, K, Ca, Db, and mP; and reduced MP, TOC content, and carbon stocks. The largest carbon stocks occurred in sites occupied by forests but previously used as pastures. Forest and pasture age influenced δ13C values, resulting in different isotopic signatures for different sites, confirming the transition from C3 to C4 plants. In 50-year-old pastures, about 66 % of soil TOC is still derived from the primary forest biomass.