ABSTRACT: In Brazil, the optimal dose of phosphorus in the cultivation of yerba mate (Ilex paraguariensis St. Hil.) clones has yet to be defined. This study verified the productivity of yerba mate clones in response to the application of P doses and determined the critical level of the nutrient in soil and yerba mate leaves. The experiment was developed in Itaiópolis-SC, in humic cambisol, from 2013 to 2020. Five doses of the nutrient were evaluated in two clones (BRS-BLD Aupaba and F2) of yerba mate. Fertility was defined by planting/post-planting (0, 2.3; 4.5; 6.8, and 9.0 g plant-1), canopy formation 1 (0, 10, 20, 30, 40, and 50 g plant-1), canopy formation 2 (0, 15, 30, 45, and 60 g plant-1), and production (0, 16.7; 33.3; 50.0; 66.7 kg ha-1). Harvests took place between July 2015 and January 2020, at 18-month intervals. The productivity of leaves, fine branches, and thick branches was evaluated. In the 2020 harvest, soil and leaf samples were collected to determine the critical level of P. The productivity of clone components increased with phosphate fertilization in all evaluated harvests. The critical levels of P for clones, Aupaba and F2, were 5.2 and 6.3 mg dm-3 in soil and 1.03 and 1.11 g kg-1 in leaves, respectively. Yerba mate is demanding of P, expressing maximum productivity in the planting phase, canopy formation 1 and 2, and production when doses of 5, 25, 40 g plant-1, and 35 kg ha-1 of P2O5 are applied, respectively.

RESUMO: No Brasil, a dose de fósforo no cultivo de clones de erva-mate ainda não está definida. O objetivo do estudo foi verificar a produtividade de clones de erva-mate em resposta a aplicação de doses de P e determinar o nível crítico do nutriente no solo e folhas de erva-mate. O experimento foi implantado em Itaiópolis-SC, em Cambissolo Húmico, em 2013. Foram avaliadas cinco doses do nutriente em dois clones (BRS-BLD Aupaba e F2) de erva-mate. As adubações foram definidas como de plantio/pós-plantio (0, 2,3; 4,5; 6,8 e 9,0 g planta-1), formação de copa 1 (0, 10, 20, 30, 40 e 50 g planta-1), formação de copa 2 (0, 15, 30, 45 e 60 g planta-1) e produção (0, 16,7; 33,3; 50,0; 66,7 kg ha-1). As colheitas ocorreram entre julho de 2015 e janeiro de 2020, com intervalos de 18 meses. Avaliou-se produtividade de folhas, galhos finos e galhos grossos. Na safra de 2020, foram coletadas amostras de solo e folhas para determinação do nível crítico de P. A produtividade dos componentes dos clones aumentou com a adubação fosfatada em todas as safras avaliadas. Os níveis críticos de P para os clones Aupaba e F2 foram 5,2 e 6,3 mg dm-3 no solo e 1,03 e 1,11 g kg-1 nas folhas, respectivamente. A erva-mate é exigente em P, expressando produtividade máxima na fase de plantio, formação de copa 1 e 2 e produção, quando aplicado doses de P2O5 em torno de 5, 25, 40 g planta-1 e 35 kg ha-1, respectivamente.

ABSTRACT Bases are chemical species that donate electrons, accept protons, or release hydroxyls (OH–) in aqueous solution. In Soil Science, “base saturation”, “exchangeable bases” or “basic cations” has been widely used to distinguish Ca2+, Mg2+, Na+, and K+ from H+ and Al3+ cations. This terminology is confusing since none of these cations are truly a base in chemistry sense. However, in the absence of the proposition of a correct term, the term “base saturation” remains in use nowadays, causing confusion among students, professionals, and even among professors and researchers in Soil Science, as it leads to the erroneous interpretation that the soil acidity can be corrected by adding these cations to the soil. Here, we present the historical background of this nomenclature and a theoretical foundation that justifies the abolition of the use of these terms in Soil Science. We consider that the most correct is to call it “Ca-Mg-K-Na saturation”, which, despite being long, would refer directly and without any misinterpretation of the terminology. In Soil Fertility, the “base saturation” is often calculated only as a function of the sum of Ca, Mg, and K, since the Na content is negligible in most tropical and subtropical soils. Thus, one could use the term “Ca-Mg-K saturation”. Likewise, it is also suggested to abolish the use of the term “sum of bases” and use the term “sum of Ca-Mg-K” or “sum of Ca-Mg-K-Na” instead when necessary.

RESUMO A fertilização com nitrogênio é essencial para a produtividade e qualidade do trigo, mas precisa ser mais precisa, e o uso de sensores ópticos proximais no campo pode auxiliar neste objetivo. O objetivo deste estudo foi avaliar se é possível estimar com o índice de vegetação por diferença normalizada (NDVI), obtido durante a fase de crescimento do trigo, a produtividade de grãos e a qualidade tecnológica da farinha de cultivares submetidas a doses de nitrogênio. O experimento foi conduzido a campo no município de Ponta Grossa, PR, Sul do Brasil. O delineamento experimental foi em blocos casualizados em esquema fatorial 4 × 6 com quatro repetições. Foram avaliadas as cultivares Quartzo, Gralha Azul, Sinuelo e Toruk, combinadas com seis doses de N (0, 40, 80, 120, 160 e 200 kg ha-1 de N). Os valores de NDVI foram sensíveis tanto às doses de nitrogênio quanto às diferentes cultivares. Houve relação do NDVI com a produtividade de grãos e teores de proteína e glúten da farinha. A força de glúten, estabilidade, tenacidade, extensibilidade da massa e a razão tenacidade/extensibilidade puderam ser estimados pelo NDVI obtido no início do ciclo, mas não para todas as cultivares. As determinações de NDVI com sensor óptico GreenSeeker ativo em trigo, são eficientes para estimar em campo a produtividade de grãos e a qualidade da farinha, permitindo gerar modelos de estimativa destas variáveis separadamente para cada cultivar.

ABSTRACT Nitrogen fertilization is essential for wheat yield and quality but needs more accuracy, and the use of proximal optical sensors in the field can assist in this goal. This study aimed to verify if it is possible to use the normalized difference vegetation index (NDVI) obtained throughout the wheat growth phase to estimate the grain yield and the technological quality of the flour from cultivars submitted to nitrogen doses. The experiment was conducted at field conditions in Ponta Grossa, PR, Southern Brazil. The experimental design was randomized blocks in a 4 × 6 factorial scheme with four replicates. The cultivars Quartzo, Gralha Azul, Sinuelo, and Toruk, combined with six doses of N (0, 40, 80, 120, 160, and 200 kg ha-1 of N), were evaluated. The NDVI values were sensitive to both nitrogen doses and the different cultivars. There was a relationship between NDVI and grain yield, protein, and gluten concentration of flour. The NDVI estimated the gluten strength, stability, tenacity, extensibility of the mass, and tenacity/extensibility ratio of the flour obtained at the beginning of the cycle, but not for all cultivars. The determinations of NDVI with active optical sensor GreenSeeker in wheat are efficient to estimate the grain yield and the flour quality under field conditions, allowing to generate models for estimation of these variables separately for each cultivar.

ABSTRACT Biomass produced in agricultural areas stores energy that can be used, contributing to regional development. Among the widely cultivated agricultural species is oats, destined for the production of not only grains and forage, but also biomass. The objective of this study was to characterize oat biomass in terms of the potential for energy generation considering the genetic and cultivation environment variability. Four field experiments were conducted in the state of Paraná and one in the state of São Paulo, Brazil, with black oat (Avena strigosa) and white oat (Avena sativa) cultivars. At the milky grain stage, plants were collected to quantify the production of shoot biomass and its qualitative variables for energy production and energy potential. Biomass yield varied between cultivars and cultivation sites. The mean higher calorific value was 17.9 MJ Kg-1, varying more between cultivation sites than between cultivars, being inversely proportional to the ash content. The contents of carbon, fixed carbon, volatile materials and nitrogen in the biomass did not vary between oat cultivars. The power generation potential varied widely between cultivars and cultivation sites, from 1557 to 3091 KWh ha-1, influenced mainly by the biomass yield, which overlaps the effects of the variations found in biomass quality. We concluded that oats are a species with high potential for use as an energy product, and the selection of the most productive cultivars regionally is crucial.

RESUMO A biomassa produzida em áreas agrícolas armazena energia que pode ser aproveitada, contribuindo para o desenvolvimento regional. Entre as espécies agrícolas amplamente cultivadas está a aveia, destinada tanto para a produção de grãos e forragem quanto de biomassa. Este trabalho teve por objetivo caracterizar a biomassa da aveia quanto ao potencial de geração de energia considerando a variabilidade genética e de ambiente de cultivo. Para isso, foram conduzidos quatro experimentos a campo no estado do Paraná e um no estado de São Paulo, Brasil, com cultivares de aveia preta (Avena strigosa) e branca (Avena sativa). No estádio de grão leitoso as plantas foram coletadas para quantificar a produção de biomassa aérea e suas variáveis qualitativas para produção de energia e o potencial energético. A produtividade de biomassa variou entre as cultivares e locais de cultivo. A média do poder calorífico superior foi de 17,9 MJ Kg-1, variando mais entre os locais de cultivo que entre as cultivares, e sendo inversamente proporcional ao teor de cinzas. Os teores de carbono, carbono fixo, materiais voláteis e de nitrogênio na biomassa não variaram entre as aveias. O potencial de geração de energia variou amplamente entre cultivares e locais de cultivo, desde 1557 até 3091 KWh ha-1, influenciado principalmente pela produtividade de biomassa, que sobrepõe os efeitos das variações encontradas na qualidade da biomassa. Concluímos que a aveia é uma espécie com elevado potencial para uso como produto energético, sendo determinante a seleção das cultivares mais produtivas regionalmente.

Abstract Strawberry (Fragaria x ananassa Duch.) production by using the semi-hydroponic fertigation system, is an increasingly adopted technology. One of the main challenges of this system is the nutritional management of nitrate (NO3 -) and ammonium (NH4 +), which can affect fruits development and quality. This work aims to determine the NO3 -:NH4 + ratio of the nutrient solution for better quality of strawberry fruits grown in a semi-hydroponic system. ‘San Andreas’ strawberry runners were planted in an organic substrate composed by charred rice husk and pine bark. The NO3 -:NH4 + proportions evaluated in fertigation were 100:0; 75:25; 50:50; 25:75 and 0:100. Leaf nitrogen contents and aerial dry mass loss showed a proportional increase concomitantly NH4+ increase on the solution. Leaf area and chlorophyll content increased up to 29% NH4 + in the nutrient solution, while higher concentrations negatively affected these characteristics. Chemical fruits’ features were not affected by the NO3 -:NH4 + ratio, but the pulp firmness decreased as the NH4 + increased in the nutrient solution. Results obtained showed the best strawberry fruits development and quality were obtained by applying NO3 -:NH4 + in fertigation solution at the ratio of 71:29.

Resumen La producción de fresa (Fragaria x ananassa Duch.) mediante el uso del sistema de fertirrigación semihidropónico es una tecnología cada vez más adoptada. Uno de los principales desafíos de este sistema es el manejo nutricional del nitrato (NO3 -) y el amonio (NH4 +), que pueden afectar el desarrollo y la calidad de los frutos. Esta investigación tuvo como objetivo determinar la mejor relación NO3 -:NH4 + para una mejor calidad de frutos de fresa cultivados en un sistema semihidropónico. Los corredores de fresa ‘San Andreas’ se plantaron en sustrato orgánico compuesto por cáscara de arroz carbonizada y corteza de pino. Las proporciones de NO3 -:NH4 + evaluadas en fertirrigación fueron 100: 0; 75:25; 50:50; 25:75 y 0:100. El contenido de nitrógeno de las hojas y la pérdida de masa seca aérea mostraron un aumento proporcional concomitantemente con un aumento de NH4 + en la solución. El área foliar y el contenido de clorofila aumentaron hasta 29% de NH4 + en la solución nutritiva, mientras que concentraciones más altas afectaron negativamente estas características. Las características químicas de las frutas no se vieron afectadas por la relación NO3 -:NH4 +, pero la firmeza de la pulpa disminuyó a medida que aumentaba el NH4 + en la solución nutritiva. Los resultados obtenidos mostraron que los frutos de fresa con mejor desarrollo y calidad se obtuvieron aplicando NO3 -:NH4 + en solución de fertirrigación en la proporción de 71:29.

ABSTRACT: The objective of this study was to calibrate and validate models to estimate dry biomass of maize and soybean crops in the Campos Gerais region, located in the subtropical zone in southern Brazil, with incident solar radiation (Rs), growing degree days (GDD), days after planting (DAP) and precipitation (P) as variables. The experiments were carried out in the 2006/2007 and 2007/2008 harvests in Castro and Ponta Grossa cities, in four phenological stages, to obtain dry biomass. The climate data came from the ABC Foundation agrometeorological stations, installed close to the experimental areas. The parameters adjustment was performed by the Least Squares Method and using a spreadsheet Solver. The soybean harvests with the highest DAP, Rs, and P until physiological maturation were not the ones that obtained the highest final dry biomass productivity, except for the GDD variable. As sowing was performed later, the soybean crop cycle decreased. With the exception of the models' performance for the precipitation variable (between "Terrible" and "Excellent") for soybean and maize crops, the other variables presented promising performances between "Bad" and "Excellent", with a predominance of "Excellent".

RESUMEN: El objetivo de este estudio fue calibrar y validar modelos para estimar la biomasa seca de cultivos de maíz y soja en la región de Campos Gerais, ubicada en la zona subtropical del sur de Brasil, con las variables radiación solar incidente (Rs), grados días como acumulado (GDA), días después de la siembra (DAP) y precipitación (P). Los experimentos se realizaron en las cosechas 2006/2007 y 2007/2008, en los municipios de Castro y Ponta Grossa, en cuatro etapas fenológicas, para obtener biomasa seca. Los datos climáticos son de las estaciones agrometeorológicas de la Fundación ABC, instaladas cerca de las áreas experimentales. Los parámetros se ajustaron mediante el método de mínimos cuadrados y la herramienta Solver de una hoja electrónica de cálculo electrónica. Los cultivos de soja que presentaron mayor DAP, Rs y P hasta alcanzar la etapa de maduración fisiológica no fueron los que obtuvieron mayor productividad final de biomasa seca, a excepción de la variable GDA. Como la siembra se llevó a cabo tardíamente, el ciclo de la soja disminuyó. Con excepción del desempeño de los modelos de precipitación (entre "Terrible" y "Excelente") para soja y maíz, las otras variables mostraron comportamientos prometedores entre "Malo" y "Excelente", con predominio de "Excelente".

Abstract The main destination of manure is the application to croplands near livestock farms as nutrient source to enhance crop production. The aim of this study was to define the dairy liquid manure (DLM) dose, complementary to the mineral fertilizer, for higher crops yield, in rotation black oat-maize-wheat-soybean, and to identify the soil chemical variables improved by the manure that most affect the yield, in long-term. The experiment was conducted from 2006 to 2015, in no-tillage system, at Paraná State, Brazil. The soil was a Latossolo Bruno Distrófico típico, clayey texture. The treatments consisted by doses of DLM (0, 60, 120 and 180 m3 ha-1 year-1), complementary to the mineral fertilizer (applied in the same amount for all DLM doses). Crops yield and soil chemical variables were evaluated at six depths (0-10; 10-20; 20-30; 30-40; 40-50 and 50-60 cm). The DLM application increased the yield of all crops, but not in all harvests. The DLM even applied at soil surface improved the soil chemical variables in deep layers, resulting in high positive correlation between yield and exchange bases, P, Zn and Mn contents, and high negative correlation with Ca/Mg ratio and potential acidity at depth 0-10 cm. The DLM dose, complementary to the mineral fertilization, that provided higher soybean and wheat yield was about 130 m3 ha-1 year-1, while for maize this dose was equal to or greater than 180 m3 ha-1 year-1. This effect was not attributed to a single chemical variable but the improvement of all chemical variables evaluated.

Resumo O objetivo foi verificar a influência da aplicação de biofertilizante resultante da produção de energia a partir de biomassa de milho na absorção de nutrientes por plantas de pera durante o ciclo de cultivo, e na qualidade dos frutos. O experimento foi realizado em Ferrara (Itália), num pomar da cv. Abate Fétel, sobre Calcisolo Síltico Háplico. Os tratamentos consistiram em controle (sem aplicação) e biofertilizante (aplicação de 30 m3 ha-1 de biofertilizante, localizada na fila), com quatro repetições. Foram avaliados: N mineral, biomassa e respiração microbiana no solo; teor de nutrientes em folhas; e parâmetros de qualidade dos frutos. A aplicação de biofertilizante aumentou a disponibilidade de N mineral, a biomassa e respiração microbianas, e mesmo assim o teor deste nutriente não aumentou nas folhas. Os teores dos nutrientes foliares variaram durante a estação de crescimento e a aplicação de biofertilizante aumentou os teores de potássio, fósforo e zinco nas folhas maduras; enquanto reduziu o teor de magnésio e manganês foliar. A aplicação de biofertilizante reduziu o teor de massa seca, de sólidos totais e de boro dos frutos, sem efeito na firmeza e na acidez titulável. O biofertilizante teve efeito positivo sobre a dinâmica do N mineral no solo e a microbiota edáfica, alterando o teor de nutrientes nas folhas, favorecendo a produção de frutos.

Abstract The aim of this study was to verify the influence of biofertilizer application resulting from energy production from corn biomass on nutrient uptake by pear plants during the growing cycle, and on fruit quality. The experiment was carried out on a Siltic Haplic Calcisol in the Italian province of Ferrara, in a medium-density Abbé Fétel commercial orchard. Treatments consisted of control (no application) and biofertilizer (30 m3 ha-1 biofertilizer application on the row), with four replicates. The following variables were evaluated: mineral N, microbial biomass and respiration in soil; nutrient content in leaves; and fruit quality. Biofertilizer application increased soil mineral N availability; soil microbial biomass and respiration, but the content of this nutrient did not increase in leaves. Leaf nutrient concentration varied during growth season and biofertilizer application increased potassium, phosphorus and zinc concentration in mature leaves and reduced leaf magnesium and manganese concentration. Biofertilizer application reduced fruit dry matter content, total soluble solids and boron concentration, with no effect on fruit firmness and titratable acidity. Biofertilizer application has positive effect on soil mineral N dynamics and soil microflora, altering the content of nutrients in leaves, favoring fruit production.

ABSTRACT Gypsum can be used as a source for calcium (Ca) and sulphurum (S) for plants, as well as an acid, that is, a natural soil conditioner. Aiming to determine the influence of gypsum on the development of Eucalyptus urograndis in Brazil, an experiment was conducted at two locations in Paraná State. Experiments were conducted with rates of 0, 0.3, 0.6, 1.2, 2.4, 4.8 and 9.6 Mg ha-1 to verify the method of broadcast planting in a randomized block design with four repetitions. Diameter and height of plants were measured every six months and volume was determined after 36 months. There was a difference in Eucalyptus growth between the two areas, possibly related to differences in planting season and climate. Gypsum did not influence on the dendrometric growth of Eucalyptus trees. The lack of a response to gypsum, as a source of Ca, S and soil conditioner, was discussed based on soil type, Eucalyptus tolerance to soil acidity, and climatic conditions in the period evaluated.

ABSTRACT. The effect of tillage system (NT-no tillage; CT-conventional tillage; MT-minimum tillage; and NT/scarification, every three years) on soybean nutrient availability and yield was evaluated on Oxisol after 12 years of cultivation. Soil samples were collected at depths of 0.00-0.05, 0.05-0.10, and 0.10-0.20 m and were analyzed for P, K, Ca, Mg, carbon (C), organic matter (OM), pH value, potential CEC, base saturation (BS%), and number of semiquinone organic radicals. The macronutrient concentration in the leaves and amount accumulated in the plants at the blooming stage were determined, as well as the yield of the two soybean crops. The soil pH value, BS% and K, Ca, and Mg concentrations were not influenced by the tillage system. The soil P and OM in the surface layer, however, were inversely proportional to the intensity of soil preparation. The P content in the soil surface layer under NT was twice as high as that of soil under CT. The P content in the soybean leaves under NT was also higher compared to that in the plants under CT and MT. The number of semiquinone radicals was low in the soil surface layer under NT, indicating a small degree of humification. However, soybean yield was not affected by the tillage system.

ABSTRACT Residual biomass from grains has potential as an energetic source. Biomass composition determines this potential and is related to plant nutrition, which may vary according to soil fertility. The aim of this 23-year field study was to evaluate changes in chemical attributes of a Brazilian Oxisol and in the energetic potential of oat (Avena sativa L.) and soybean (Glycine max (L.) Merr) residual biomasses provided by tillage systems and fertilizer rates. The trial was performed since 1989, assessing soil chemical attributes in no-tillage (NT), conventional (CT), minimum (MT) and no-tillage plus chisel plough (NT+CP), with two fertilizer rates (normal and reduced, since 1994). Oat and soybean (2012/2013) residual biomasses were collected and analyzed by its elemental composition, higher heating value (HHV) and theoretical potential for electricity production. The NT system presented higher P-resin availability; NT and NT+CP provided higher OM and total P content on soil surface. Without appropriate amounts of K and P fertilizer, P-resin and P total contents diminished mainly in 0-0.1 m depth, while exchangeable, non-exchangeable and total K+ fractions were mined even in deeper layers (0-0.3 m). The better general fertility conditions were achieved by conservative tillage systems, with normal fertilizer rate. Soil fertility levels changed chemical composition of both biomasses but had no effect on biomass HHV. Considering a system with oat and soybean grain production plus residual biomasses for energetic exploitation, it could be possible to generate 2,941 GWh·year–1, while still achieving 70% residue coverage under no-tillage maintenance.

ABSTRACT Variations in chemical and mineralogical properties of a soil can occur at short vertical and horizontal distances. The objective of the present study was to evaluate the chemical and mineralogical soil properties of different aggregate classes from young (Ustrochrept) and highly weathered (Acrustox) soils from the state of Paraná, Brazil. Undisturbed blocks (0.20 ×0.20 ×0.20 m) of soils were separated into aggregate classes: Acrustox – 8.0-4.0 mm; 4-2 mm; 2.0-0.5 mm; 0.5-0.2 mm; and <0.2 mm; and Ustrochrept – 8.0-4.0 mm; 4.0-2.0 mm; 2.0-0.5 mm; and 0.5-0.2 mm. The exchangeable K contents showed an opposite behavior for the two soils: higher contents in the Acrustox for the larger aggregate classes and higher contents in the Ustrochrept for the smaller aggregate classes. The crystallographic characteristics of hematite and goethite were variable according to the aggregate class. The goethite in the 2-4-mm aggregate class is expected to exhibit the highest reactivity for the Ustrochrept: lower growth and a more elongated form of the crystals. The smallest aggregate class presented the lowest contents of kaolinite and gibbsite in the clay fraction. Gibbsite and kaolinite in the intermediate classes presented higher growth in both soils. The studied soils present different side-by-side environments (aggregate classes) for the exploration by the root system. This means that for the precise identification of the environments explored by the roots of a single plant, field sampling should consider the aggregate class, obtained from an undisturbed soil sample. However, this is impractical in agricultural practice.

RESUMO A biomassa residual agrícola é uma importante fonte de energia e sua produção e qualidade varia com o manejo das lavouras. O objetivo deste estudo foi avaliar o efeito da distribuição de plantas e da adubação nitrogenada sobre o potencial de produção de energia da biomassa do milho cultivado sob sistema de plantio direto. O experimento de campo foi instalado no sudeste do Brasil, com cinco doses de nitrogênio (0, 60, 120, 180 e 240 kg ha-1) e dois espaçamentos entrelinhas (0,4 e 0,8 m). Foram realizadas avaliações de produtividade de grãos, produtividade de biomassa residual e potencial de bioenergia em diferentes partes da planta (grão, colmo + folha, palha da espiga e sabugo). A variação no espaçamento não alterou o rendimento de grãos. A produtividade de folhas + palha de espiga foi maior em 0,8 m do que 0,4 m de espaçamento. A aplicação de nitrogênio resultou no aumento do rendimento de grãos e da produtividade de biomassa. O nitrogênio influência o potencial da bioenergia ao aumentar a biomassa e o poder calorífico. Com a dose de 226 kg ha-1 de nitrogênio, taxa máxima para o rendimento de grãos, e considerando apenas o uso de palha da espiga e sabugo, é possível gerar 2712 kWh ha-1 de bioenergia.

ABSTRACT Agricultural residual biomass is an important source of energy, and its production and quality vary according to the crop management. This study aimed to assess the effects of plant distribution and nitrogen fertilization on the energy production potential of the biomass of maize cultivated under no tillage. The field experiment was installed in southeast Brazil using five nitrogen rates (0, 60, 120, 180, and 240 kg ha-1) and two inter-row spacings (0.4 and 0.8 m). Grain yield, residual biomass productivity, and bioenergy potential in different parts of the plant (grain, stalk+leaf, husk, and cob) were assessed. No change in grain yield was observed using narrow row spacing. Stalk+leaf and husk productivity was higher using 0.8 m than using 0.4 m of inter-row spacing. Nitrogen application resulted in increased grain yield and biomass productivity. Nitrogen influences the bioenergy potential by increasing the biomass and calorific value. Application of the maximum nitrogen fertilization rate is recommended for grain yield considering the use of only the husk and cob can generate 2712 kWh ha-1 of bioenergy.

RESUMO. Avaliou-se o efeito da calagem sobre a disponibilidade de micronutrientes à soja cultivada em solo, com diferentes tempos de cultivo sob sistema de semeadura direta (SD). Os tratamentos consistiram de número de anos sob SD (três, seis e nove anos) e cinco doses de calcário (0, 33, 67 e 100% da quantidade necessária para elevar a saturação por bases a 70%), aplicadas em superfície, mais a dose 100% incorporada na camada 0-0,20 m de um Latossolo Vermelho argiloso. Amostras de solo e de folha foram coletadas em dois estádios de vegetação da soja (V4: estádio vegetativo e R2: florescimento pleno). O solo foi amostrado nas profundidades de 0-0,05, 0,05-0,10, 0,10-0,20 e 0,20-0,30 m. A calagem superficial exerceu pouco efeito sobre os teores de micronutrientes no solo e nas folhas de soja. Na área com três anos sob sistema de SD todas as doses de calcário reduziram os teores de Zn até a profundidade de 0,20 m. A incorporação de calcário diminuiu o teor de Mn da camada superficial. Os teores de micronutrientes no solo e as concentrações nas folhas da soja não variaram com os anos de cultivo sob SD. Estes dados sugerem que as doses atualmente empregadas de calcário aplicadas na superfície de solos sob SD não necessariamente conduzem a deficiências de micronutrientes.

ABSTRACT. The effect of liming on the availability of micronutrients to soybean cultivated during different numbers of years under no tillage (NT) was investigated. The treatments consisted of the number of years under NT (three, six, and nine years) and five rates of lime (0, 33, 67 and 100% of the amount calculated to raise soil base saturation to 70%) broadcast on soil surface plus the rate of 100% broadcast with incorporation in the 0-0.20 m layer of a clayey Red Oxisol. Soil and leaf samples were collected at two vegetative stages of the crop (vegetative V4 and blossoming R2). The soil was sampled at depths of 0-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m. Surface liming had little effect on extractable soil micronutrient and nutrient concentrations in soybean leaves. In the area with three years under NT, all liming rates decreased the extractable soil Zn up to a depth of 0.20 m. Lime incorporation decreased the extractable soil Mn in the surface layer. There were no differences in the extractable soil micronutrients and nutrient concentrations in soybean leaves as a function of the number of years under NT. These data suggest that broadcasting lime at current rates on soils under NT does not necessarily lead to micronutrient deficiencies.

RESUMO O cultivo da cebola em época antecipada, apesar da menor produtividade, representa oportunidade de melhores mercado e preço aos agricultores do sul do Brasil. Conhecer a quantidade absorvida e a distribuição dos nutrientes na planta nesta condição é essencial para o manejo adequado da adubação. Para a cebola poucas informações estão disponíveis, especialmente para o cultivo orgânico e plantio em época antecipada na região sul do Brasil. O presente trabalho foi conduzido na área experimental de olericultura orgânica da estação do Canguiri-UFPR, região metropolitana de Curitiba, com o objetivo de avaliar a absorção de nutrientes e a partição destes em cultivares de cebola de polinização aberta, em sistema orgânico, com semeadura em janeiro. O delineamento experimental foi inteiramente casualizado, com três repetições. As cultivares avaliadas foram: Franciscana IPA-10, Vale Ouro IPA-11, Brisa IPA-12, Alfa Tropical, Alfa São Francisco, Alfa São Francisco-RT e BR-29. Foram realizadas análises químicas da parte aérea e dos bulbos coletados no momento da colheita. As cultivares variaram quanto ao potencial produtivo, sendo as mais produtivas mais eficientes em converter nutrientes absorvidos em produção de bulbos. O conteúdo de nutrientes ocorreu na seguinte ordem: parte aérea -K > N > P > Ca > Mg > Fe > Zn > Mn = B > Cu; bulbos - K > N > P > Ca > Mg > Fe > B > Zn > Cu > Mn. Por tonelada de bulbos frescos produzida, os nutrientes foram requeridos na seguinte ordem de quantidade K > N > P > Ca > Mg > Fe > Zn > B > Mn > Cu e, acumularam-se em maior quantidade na parte aérea, exceto o Zn, que apresentou maior concentração no bulbo.

ABSTRACT Early season onion crops, despite lower yield, is an opportunity for farmers to explore market and better prices in southern Brazil. Knowing the amount absorbed and the distribution of nutrients in the plant is essential for adequate management of fertilization. However, little information on this matter is available for onion, especially for organic farming and nontraditional periods in southern Brazil. The objective of this study was to evaluate the nutrient absorption and partitioning in open-pollinated onion cultivars grown in organic system. The experiment was conducted in the Canguiri-UFPR experimental organic farm, Curitiba-PR, with sowing in January. The experiment was arranged in a completely randomized design with three replications. Cultivars Franciscana IPA-10 (purple), Vale Ouro IPA-11 and Brisa IPA-12 (from Empresa Pernambucana de Pesquisa Agropecuária - IPA), Alfa Tropical (from Embrapa Hortaliças), Alfa São Francisco (VIII cycle) and Alfa São Francisco-RT (thrips resistant- genotype under test; from Embrapa Semi-árido), and BR-29 (Topseed-Agristar) were selected for the study. Chemical analyses were performed for shoot and bulbs collected at harvest. The production potential of cultivars varied, and the most productive ones were the most efficient in converting the nutrients absorbed in bulb yield. The order of nutrient contents in the shoots was K > N > P > Ca > Mg > Fe > Zn > Mn = B > Cu, whereas in the bulbs it was K > N > P > Ca > Mg > Fe > B > Zn > Cu > Mn. Nutrients were required in the following order of amount K > N > P > Ca > Mg > Fe > Zn > B > Mn > Cu, per ton of fresh bulbs, and accumulated in greater quantity in the shoot, except Zn, which had higher concentration in the bulb.