ABSTRACT Lettuce (Lactuca sativa) is the main leafy vegetable produced in Brazil. Since its production is widespread all over the country, lettuce traceability and quality assurance is hampered. In this study, we propose a new method to identify the geographical origin of Brazilian lettuce. The method uses a powerful data mining technique called support vector machines (SVM) applied to elemental composition and soil properties of samples analyzed. We investigated lettuce produced in São Paulo and Pernambuco, two states in the southeastern and northeastern regions in Brazil, respectively. We investigated efficiency of the SVM model by comparing its results with those achieved by traditional linear discriminant analysis (LDA). The SVM models outperformed the LDA models in the two scenarios investigated, achieving an average of 98 % prediction accuracy to discriminate lettuce from both states. A feature evaluation formula, called F–score, was used to measure the discriminative power of the variables analyzed. The soil exchangeable cation capacity, soil contents of low crystalized Al and Zn content in lettuce samples were the most relevant components for differentiation. Our results reinforce the potential of data mining and machine learning techniques to support traceability strategies and authentication of leafy vegetables.

RESUMEN Los sistemas agrícolas pueden alterar las propiedades física e hidráulicas del suelo y, en consecuencia, su calidad. Nuestro objetivo fue determinar y asociar las propiedades física e hidráulicas de cuatro tipos de suelo bajo un sistema de siembra directa sobre rastrojo, localizados en la región subtropical de Brasil, así como crear un conjunto de datos disponibles que pueden ser utilizados en estudios posteriores. Fueron recolectadas muestras de suelo alteradas y inalteradas en tres camadas: 0,0 - 0,10 m; 0,10 - 0,25 m; y 0,25 - 0,40 m en seis localidades de los estados de Paraná y São Paulo. Fueron determinados la textura del suelo, la densidad aparente y de las partículas del suelo, la porosidad (total, macro y micro), la humedad volumétrica del suelo (punto de marchitez permanente y capacidad de campo), la capacidad de agua disponible y la conductividad hidráulica saturada. El promedio de la densidad aparente del suelo está dentro de limites considerados óptimos (1000 kg m(3 y 1400 kg m(3) de acuerdo con las clases texturales del suelo. El promedio de la porosidad total según los suelos estudiados (entre 0.47 m3 m-3 y 0.63 m3 m-3) se mantuvo próxima a la condición ideal para el desarrollo anual de la cultura en sistema de siembra directa sobre rastrojo. La proporción entre micro y macroporos fue de aproximadamente 2:1. El promedio de la capacidad del agua disponible del suelo ha variado entre 48 mm y 60 mm. La conductividad hidráulica saturada promedio fue clasificada como “moderada”. El manejo adoptado por más de 20 años en las áreas estudiadas no presentó alteración en las once propiedades físicas e hidráulicas del suelo, al compararlo con los límites normales establecidos en la literatura.

ABSTRACT Agricultural systems can alter the soil physical and hydraulic properties, and consequently its quality. We aimed to determine and associate the physical and hydraulic properties of four soil types under no-tillage system in the Subtropical region of Brazil, as well as to create a data set available to be explored by further studies. Disturbed and undisturbed soil samples were collected from three layers: 0.0 - 0.10 m; 0.10 - 0.25 m; and 0.25 - 0.40 m at six localities in the Paraná and São Paulo States. Soil texture, soil bulk density and particle density, porosity (total, macro and micro), volumetric water content (permanent wilting point and field capacity), available water capacity and saturated hydraulic conductivity were determined. The average soil bulk density was within 1000 kg m(3 to 1400 kg m(3, which is considered optimum for the respective soil textures. The average total porosity (between 0.47 m3 m-3 and 0.63 m3 m-3) was close to an optimal condition for annual crop development under no-tillage system. The proportion between micro and macropores was approximately 2:1. The average values of soil available water capacity ranged from 48 mm to 60 mm. The average for the saturated hydraulic conductivity was classified as “moderate”. The management adopted for more than 20 years in the studied areas did not bring about critical values for the eleven physical and hydraulic soil properties examined, when compared to acceptable ranges verified in literature.

Abstract Fertilization can be a sustainable management practice for the maintenance of the threatened species such as Araucaria angustifolia. Our objective was to evaluate the elemental composition of A. angustifolia fertilized with N, P, and K, and how the fertilization altered the soil fertility. Seven-month-old seedlings were transplanted to 16 dm3 soil pots, and three experiments were carried separately (one for each cited element) in a completely randomized design. Overall, the seedlings tended to accumulate nutrients differently among the compartments in the following order: needles > branches > stem. Application of N reduced the soil pH, boosted Mn concentration in more 10 times, decreased the P uptake, and changed the C:N and C:P ratios. Increased doses of P led to higher uptake rates but promoted a reduction in the absorption of Mg. High rates of K diminished of P, Ca, Mg, Mn, and B, confirming antagonism interaction with Ca and Mg.

ABSTRACT Our aim was to assess the mineral composition of corn silages produced in four states of Brazil: Goiás, Minas Gerais, Paraná, and Santa Catarina. In total, seventy-three samples were analyzed. Total element content was extracted by HNO3 and H2O2 microwave-assisted digestion, and inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine concentration. Of the 31 elements analyzed (Ag, Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cs, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Se, Sr, Ti, Tl, U, V, and Zn), 21 had concentrations above equipment detection limits. No elements reached the maximum tolerable concentration, but concentrations of Ca (0.14-0.15%), Cu (3.4-5.6 mg kg−1), P (0.13-0.16%), S (0.06-0.08%), and Zn (13-19 mg kg−1) were below the adequate concentration for good nutritional balance. The strong and consistent correlation observed between Fe and Ti in silage samples indicated contamination by soil. Mean concentrations of Cu, Mn, Mo, P, S, and Zn were different among states, and canonic analyses successfully discriminate samples according to their state of origin. Minerals from corn silage should be considered when formulating balanced cattle diets. To ensure silage quality, farmers must adopt strategies that reduce contamination by soil during the ensiling process.