O presente trabalho consistiu na coleta de amostras de solos para análise e descrição dos valores de metais pesados em áreas agrícolas de alguns municípios do estado do Tocantins. O objetivo é fazer comparações com os Valores de Referência estabelecidos para os estados de São Paulo (SP) e Minas Gerais (MG), uma vez que não existem valores de referência para o estado do Tocantins. Amostras de solo foram coletadas em 27 áreas agrícolas e submetidas ao método de digestão EPA3051, proposto pela Agência de Proteção Ambiental (EPA). As amostras de solos apresentaram diferentes níveis de concentração de metais pesados, com arsênico (As), mercúrio (Hg) e selênio (Se) sendo mais constantes. Não houve níveis de metais pesados próximos aos Valores da Pesquisa Agrícola, apenas alguns elementos excederam o limite dos Valores de Prevenção e os Valores de Referência da Qualidade (QRV) propostos para os estados de SP, bem como para o QRV estabelecido para as áreas no estado de MG. Essas concentrações, no entanto, não apresentam risco de contaminação do solo.

Unchanged reference values of grain nutrient contents for corn have been used for over 20 years, despite yield increases, the development of new hybrids, and modifications to cropping systems, especially the establishment of in-season second crops and the wide adoption of no-tillage. This study measured macro-and micronutrient contents in corn grains from different regions, in the first (summer) and second (fall) crop, to update the reference values of estimated nutrient removal. A secondary objective was to determine whether there were correlations between grain nutrient contents and grain yields and densities. In this study, 175 corn grain samples of experiments on cultivar evaluation and 22 samples from soil management trials from five states (SP, PR, MG, MT, and MS) were used. Grain nutrient contents were ranked as follows: N > K > P > Mg > S (g kg(-1)) and Ca > Zn > Fe > Mn > B > Cu (mg kg(-1)). Content values for half of the nutrients analyzed were negatively correlated with yield and/or seed weight, whereas grain density was not correlated with nutrient contents. For the first crop of corn, the N, S, and Cu contents clearly decreased with increases in grain yield and seed weight, indicating a lower nutrient removal at higher yields. The great variability of results among environments makes it difficult to differentiate between the first and second crop of corn. The reference values currently in use overestimate the removal of N, P, K, Ca, Mg, S, and Zn grain contents, but underestimate Cu and B in corn. The results of this study can be used to update the reference values of nutrient contents of corn grains to better estimate nutrient removal from the soil.

ABSTRACT Concerning the baby leaf production in trays, substrate can be reused for a certain number of times depending on its chemical and physical characteristics, but populations of pathogens such as Pythium aphanidermatum and Rhizoctonia solani that can cause damping off of lettuce, can build up during the reuse of this substrate. Solar treatment in a solar collector can be an alternative for the disinfestation of these substrates. Thus, the objective of this research was to study the reuse of coconut fiber substrate and its solar treatment in solar collector on baby leaf lettuce production. The experimental design was randomized blocks, in a factorial scheme 4 (first-use substrate, reused once, reused twice and reused three times) x 2 (with and without solar treatment), with four replications. The substrate reused 3 times provided the highest yield, 7.4 kg/m2, 14.8 cm plant height, 7.8 leaves, length and width of the largest leaf 13.9 and 4.8 cm, respectively; 3.4 and 0.21 g/plant fresh and dry mass, respectively; pH 6.8, 0.34 and 0.35 dS/m electrical conductivity, 25.1 and 30.2 mg/L NH4 + and 16.8 and 14.6 mg/L NO3 -, dry density 169 and 177 kg/m3 and water holding capacity 53 and 57% for substrates with and without solar treatment, respectively. There was an increase in the population of P. aphanidermatum, but the solar treatment was effective to eliminate this pathogen, and R. solani was not detected in the substrates. This study showed that the reuse of a coconut fiber substrate for one to three times could enhance the yield of lettuce baby leaf and promote the chemical and physical characteristics of the substrate.

No sistema produtivo de baby leaf em bandejas o substrato utilizado, bem como o sistema radicular das plantas que permanecem nas bandejas apos a colheita, tornando-se residuos. Seu reuso pode reduzir o custo de producao bem como diminuir o residuo gerado. Em substratos provenientes de reuso e possivel que exista a presenca de patogenos causadores de doencas, principalmente do tombamento na cultura de alface. Assim, a solarizacao e uma opcao para eliminacao desses patogenos. Portanto, o objetivo do presente estudo foi verificar o efeito do reuso e solarizacao do substrato a base de fibra de coco na producao de alface com a finalidade baby leaf, bem como verificar a qualidade quimica e fisica desse substrato. O delineamento experimental utilizado foi o de blocos casualizados em esquema fatorial 4x2, com quatro repeticoes. Os tratamentos foram substrato sem reuso e reutilizados por uma, duas e tres vezes, solarizados e nao solarizados. Avaliou-se altura e numero de folhas da planta, comprimento e largura da maior folha, massa fresca e seca da parte aerea e produtividade. Nos substratos, avaliou-se pH, condutividade eletrica, densidade umida, densidade seca, capacidade de retencao de agua e incidencia de Rhizoctonia solani e Pythium aphanidermatum. Verificou-se possibilidade de reuso do substrato fibra de coco por ate tres vezes. As medias das caracteristicas fitotecnicas avaliadas aumentaram com os sucessivos reusos do substrato, com destaque para a produtividade de 7,4 kg m -2 verificada no substrato de terceiro reuso. As medias das caracteristicas quimicas e fisicas do substrato aumentaram com os reusos sucessivos e possibilitaram o cultivo de alface para baby leaf, com destaque para o pH na faixa de 6,7 a 6,8 e condutividade eletrica entre 0,28 a 0,35 dS m -1 para os substratos reaproveitados. A solarizacao foi eficiente na eliminacao dos patogenos R. solani e P. aphanidermatum de todos os substratos avaliados.

A caracterização física de substratos para plantas no Brasil ainda é incipiente, embora, apenas com a definição adequada de métodos confiáveis seja possível padronizar insumos e fornecer as recomendações necessárias aos produtores. Objetivou-se caracterizar fisicamente seis substratos para plantas e comparar métodos prescritos pelo Ministério da Agricultura, Pecuária e Abastecimento brasileiro e pelo Comitê Europeu de Normatização. Os substratos avaliados foram: fibra de coco granulada, dois tipos de casca de pínus, casca de arroz estabilizada e duas misturas (50:50, v:v), uma de casca de arroz com fibra de coco granulada e a segunda de casca de pínus e casca de arroz. O projeto, realizado em 2009, teve delineamento experimental inteiramente casualizado. Os substratos apresentaram diferenças quanto aos atributos físicos: umidade, granulometria, densidade volumétrica, capacidade de retenção de água, densidade de partícula e porosidade, características com as quais se pode inferir sobre sua utilização. Quanto aos parâmetros físicos recomendados em cada um dos métodos, sugere-se: para determinação da umidade da amostra, secagem à temperatura de 65 ± 5 °C; para granulometria, tempo de 10 min de agitação das peneiras; para densidade volumétrica, método da autocompactação; para capacidade de retenção de água, a base do anel volumétrico da amostra como referência e a adoção da dupla saturação e da pré-tensão em 50 hPa; para determinar a curva de retenção de água dos substratos, os pontos de tensão em 10, 30, 50 e 100 hPa; para caracterização dos substratos quanto à sua origem, inclusão da densidade de partícula pela determinação da matéria orgânica e de cinzas.

Interlaboratory comparison programs have been found to be useful to investigate potential error sources and therefore to remove or minimize their effects. A proficiency test was performed for five soil micronutrients [boron (B), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn)] by forty-nine independent Brazilian laboratories on four duplicated soil samples. Extraction of B was performed by hot water, whereas Fe, Mn, Cu, and Zn were extracted by diethylenetriaminepentaacetic acid (DTPA). The objectives were to compare the performance of different statistical methods for assessing between-laboratory variability (reproducibility) and to quantify the variability within single laboratories (repeatability). The statistical methods employed to compare interlaboratory analytical results were (1) Agronomic Institute method (mean, standard deviation, coefficient of variation), (2) Z(1) score (mean and standard deviation, including outliers), (3) Z(2) score (mean and standard deviation, excluding outliers), (4) robust Z score (median and standardized interquartile amplitude) denoted as Z(3), (5) Cochran test, and (6) Cochran+Grubbs tests. In addition, the robust Z-score method, denoted as Z(4), was used to assess intralaboratory variability. The performance of any laboratory for the analysis of soil micronutrients varied depending on the statistical method applied. The percentage of laboratories providing satisfactory results was 79 percent (Agronomic Institute), 95 percent (Z(1)), 92 percent (Z(2)), 89 percent (robust Z(3) score), 97 percent (Cochran), and 95 percent (Cochran+Grubbs). The Z-score tests become stronger and more rigorous when outliers were excluded (Z(2)) or when the standardized interquartile amplitude was used (Z(3)). Cochran and Grubbs tests, which are based on the removal of extreme values, were weaker than the other tests evaluated. In conclusion, the method employed by the proficiency test of the Agronomic Institute for removing outliers has been found to be the strongest and strictest one, yielding a reliable comparison of the results from soil micronutrient analyses.Color versions of one or more of the figures in the article can be found online at[GRAPHICS].

Soil carbon (C) determinations are important for soil quality assessment. The standard method that is used in SAo Paulo state to determine soil organic C is a modified Walkely-Black method. This method has some disadvantages because of the time needed for implementation and the use of potassium dichromate. Therefore, the aims of this work were to test the efficiency and compare the following methods: (a) wet oxidation of organic C (OC-HO) followed by spectrophotometer determination, (b) dry incineration at 550 degrees C with a muffle furnace plus gravimetric determination (TC-I), and (c) dry combustion with a C-nitrogen (N)-sulfur (S) elemental analyzer (TC-EA). Sixty-one soil samples were collected at the 0- to 20-cm depth on agricultural soils of SAo Paulo state. Samples were dried at 65 degrees C, ground, and sieved through a 0.09-mm sieve. Carbon content was determined in triplicate. These sets of samples exhibited a wide range of C content: TC-EA was from 0.43 to 9.14 g 100 g(-1). Mean C contents were 6.76 g 100 g(-1), 2.31 g 100 g(-1), and 2.52 g 100 g(-1) for TC-I, OC-HO, and TC-EA, respectively. Moreover, in all the studied soil samples, the TC-I method overestimated the C content when compared with OC-HO and TC-EA methods. Losses of structural water and inorganic colloidal compounds, such as gibbsite, induced by high temperature during incineration probably were responsible for the greater C contents obtained by the TC-I method. Correlation coefficients between the three methods were rather similar: TC-I and TC-EA (r = 0.87), TC and OC-HO (r = 0.83), and TC-EA and OC-HO (r = 0.84). It was concluded that C extraction by the standard, routinely employed OC-HO method can be replaced by the TC-EA method, which has environmental advantages.

Efficient analytical methods for the quantification of plant-available Zn contained in mineral fertilizers and industrial by-products are fundamental for the control and marketing of these inputs. In this sense, there are some doubts on the part of the scientific community as well as of the fertilizer production sector, whether the extractor requested by the government (Normative Instruction No. 28, called 2nd extractor), which is citric acid 2 % (2 % CA) (Brasil, 2007b), is effective in predicting the plant availability of Zn via mineral fertilizers and about the agronomic significance of the required minimal solubility of 60 % compared to the total content (HCl) (Brasil, 2007a). The purpose of this study was to evaluate the alternative extractors DTPA, EDTA, neutral ammonium citrate (NAC), buffer solution pH 6.0, 10 % HCl, 10 % sulfuric acid, 1 % acetic acid, water, and hot water to quantify the contents of Zn available for maize and compare them with indices of agronomic efficiency of fertilizers and industrial by-products when applied to dystrophic Clayey Red Latosol and Dystrophic Alic Red Yellow Latosol with medium texture. The rate of Zn applied to the soil was 5 mg kg-1, using the sources zinc sulfate, commercial granular zinc, ash and galvanic sludge, ash and two brass slags. Most Zn was extracted from the sources by DTPA, 10 % HCl, NAC, 1% acetic acid, and 10 % sulfuric acid. Recovery by the extractors 2 % CA, EDTA, water, and hot water was low. The agronomic efficiency index was found to be high when using galvanic sludge (238 %) and commercial granular zinc (142 %) and lower with brass slag I and II (67 and 27 %, respectively). The sources galvanizing ash and brass ash showed solubility lower than 60 % in 2 % CA, despite agronomic efficiency indices of 78 and 125 %, respectively. The low agronomic efficiency index of industrial by-products such as brass slag I and galvanizing ash can be compensated by higher doses, provided there is no restriction, as well as for all other sources, in terms of contaminant levels of arsenic, cadmium, chromium, lead, and mercury as required by law (Normative Instruction No 27/2006). The implementation of 2nd extractor 2 % CA and the requirement of minimum solubility for industrial by-products could restrict the use of alternative sources as potential Zn sources for plants.

No Brasil, o Ministério da Agricultura, Pecuária e Abastecimento é o responsável pela legislação que regulamenta as especificações, garantias, tolerâncias, registro, embalagem e rotulagem de substratos para as plantas. Na Instrução Normativa n.º 14 e nas IN nº 17 e 31 estão as exigências quanto aos valores e aos métodos de pH, condutividade elétrica (CE), densidade seca, capacidade de retenção de água (CRA10) e umidade. Os desvios aceitáveis são de ±0,5 para o pH, ±0,3 dS m-1 para a CE, ±15% para densidade seca, até -10% (m/m) para a CRA10 e até +10% para umidade. O objetivo deste trabalho foi avaliar as medidas de pH, CE, densidade seca, CRA10 e umidade de diversos substratos para as plantas, durante o período de seis meses de armazenamento, fornecendo subsídios técnicos para a legislação brasileira. Utilizaram-se nove amostras de substratos comerciais, orgânicas e inorgânicas. Alguns desvios em relação à faixa tolerada pela normativa brasileira foram observados para o pH, CE, CRA10 e umidade em 5,4,6 e 2 amostras respectivamente. Os resultados de densidade seca estavam dentro da faixa permitida pela legislação brasileira. A CRA10 foi a de maior restrição quanto à legislação brasileira, seguida dos valores de pH. Sugere-se o aumento da tolerância para CRA de -15% (m/m) e para o valor de pH±1,0. Além disso, recomenda-se uma reavaliação por parte dos produtores de substratos em relação às matérias-primas constituintes de alguns substratos ou do tempo de armazenamento.

In Brazil, the Ministry of Agriculture, Livestock and Provision is responsible for regulating specifications, warranties, tolerance thresholds, registration, packing and labeling of substrates for plants. In the INs (Normative Instruction) n.degrees 14, 17 and 31 are included the requirements for pH, electrical conductivity (EC), density, water holding capacity (WHC10) and humidity. The acceptable deviations are +/-0.5 for pH, +/-0.3 dS m(-1) for EC, +/-15% for density, up to -10% w/w for WHC and up to +10% for humidity. The aim of this study was to evaluate the pH, EC, density, humidity and WHC10, of several substrates for plants, during a six months period of storage, thus, providing technical assistance to Brazilian regulations. Nine commercial substrates were used, both organic and inorganic. Some deviations from the maximum thresholds required by Brazilian regulation were observed for pH, EC, WHC10 and humidity in 5, 4, 6 and 2 samples, respectively. Density showed values within the range permitted by Brazilian regulations. WHC10 was the variable showing the greatest restriction regarding the Brazilian regulation, followed by pH. It is suggested that tolerance should be increased to -15% for WHC10 (w/w) and pH value to +/-1.0. In addition, producers should reassess the raw materials constituting the substrates or of the storage time.

This work aimed to evaluate the biodegradation of the chelant agents EDDS and EDTA through soil respiration. The chelant agents were applied in two soils, one was an Inceptisol contaminated with heavy metals and the other was a no contaminate Oxisol. Three doses of each chelant (250, 500 and 750 mg kg(-1)) and one dose of glucose were applied in both the soils tested, with three replicates:The chelant biodegradation was determined by quantifying the CO(2) emitted during the experiment. The chemical kinetics equations used did not fit the data satisfactory for both chelants on the Oxisol, while a half-life of 12-16 days for EDDS and of 6 days for EDTA was obtained for the Inceptisol. During the half-life period, a chelant degradation of only 15% was observed. For the Oxisol, EDTA was responsible for the lowest biodegradation rate, next to zero, which occurred at lowest dose added. EDDS caused the highest biodegradation (135%) at the highest dose added to the soil. For the Inceptisol, the lowest biodegradation rate (19.2%) was observed with the highest dose of EDTA and the largest degradation rate (211.4%) with the EDDS at the lowest dose. Both the chelants degraded less with the increase of their respective doses, except with the application of the lowest dose of the EDDS (250 mg kg(-1)). However, the biodegradation of the EDDS continued greater than that verified with the EDTA application.

Este trabalho objetivou avaliar a degradabilidade dos quelantes EDTA e EDDS por meio do monitoramento da respiração do solo. Os quelantes foram aplicados em dois solos, um Cambissolo Háplico contaminado por metais pesados e um Latossolo Vermelho-Amarelo não contaminado. Três doses de cada quelante (250, 500 e 750 mg kg-1) e uma dose de glicose foram aplicadas em ambos os solos testados, com três repetições cada uma. A degradação dos quelantes foi determinada por meio da quantificação do CO2 emanado do início até o término do ensaio. As equações de cinética química não se ajustaram satisfatoriamente para ambos os quelantes no Latossolo, enquanto para o Cambissolo Háplico resultaram em valores de meia-vida entre 12-16 dias para o EDDS e de 6 dias para o EDTA. Nesse período, a quantidade degradada de EDTA foi de 15% somente. Para o Latossolo o EDTA foi responsável pela menor taxa de degradação, próxima de zero, ocorrida na menor dose, e o EDDS pela maior taxa (135%), ocorrida na maior dose. Para o Cambissolo Háplico, a menor taxa de degradação (19,2%) coube ao EDTA na maior dose e a maior taxa (211,4%), ao EDDS na menor dose. Ambos os quelantes tiveram redução da taxa de degradação com o aumento de suas respectivas doses, exceto com a aplicação da menor dose do EDDS (250 mg kg-1). Contudo, a degradabilidade do EDDS continuou maior que a verificada com a aplicação do EDTA.

A greenhouse study was conducted to evaluate the effects of ethylenediamine tetraacetic acid (EDTA) addition to soils on the lead (Pb) phytoextraction potential of jack beans (Canavalia ensiformis L.). In a pot experimentSoil samples (dystrophic Rhodic Hapludox) were treated with six Pb rates (0, 100, 200, 350, 1,200, and 2,400 mg kg(-1) soil) applied as Pb(NO3)(2) without and with EDTA application (0 and 0.5 g kg(-1), respectively). Lead, Cl-, NO3-, NH4+, SO42-, H2PO4-, Zn2+, Cu2+, Fe3+, Al3+, Ca2+, Mg2+, K+ and DOC (dissolved organic carbon) concentrations obtained in a saturation soil extract (soil: water ratio of 1:0.3) were used for Pb speciation by means of the software Visual-Minteq 2.30. Soil Pb-availability was assessed with Diethylene triamine pentaacetic acid (DTPA) extraction. EDTA treated soils showed higher Pb (as PbEDTA(2-)), and Fe (as FeEDTA(-)) concentrations in soil solution leading to higher uptake of these elements by the jack bean. On the other hand, it decreased the concentration of stable complexes as Pb-DOC and Fe-DOC. EDTA also induced better nutrition to plants building up the concentration of non target metals (Ca, K, Mg, Zn, Cu, Fe and Mn) in shoots. Shoot dry matter yield remained constant even at the highest Pb rates after EDTA treatment. Jack bean can be considered as a potential Pb-phytoextractor. In addition, the DTPA solution was effective to assess Pb availability to the plants at all applied Pb rates.

Fields studies were conducted in 2004/2005 in order to evaluate the effects of tillage on nutrient content in aboveground biomass of two peanut cultivars, cultivated in rotation after mechanical harvested sugarcane and pastures. These trials were carried out in two types of soils; Oxisol and Ultisol, respectively in Ribeirao Preto and Mirassol, Sao Paulo State, Brazil. The experimental design was split-plot with four replications. Tillage treatments (conventional, minimum and no-tillage) were main plots while sub-plots were peanut genotypes IAC-Tatu ST (Valencia market-type, erect growth habit, red seed coat, maturity range around 100 days after planting) and IAC-Caiapo (Runner market-type, prostate growth habit, pink testa, maturity range more than 135 days). From 15 to 90 days after emergence, samples of leaves and stems were harvested, dried, weighted and ground to determine macro and micronutrient concentration. At 75 days after sowing, the cultivar IAC-Caiapo showed higher contents of N, P, K, Cu, and Zn while IAC-Tatu presented higher concentrations of Ca, Mg, and S. Zn content was higher in conservation tillage than in conventional, mainly in Oxisoil for both of cultivars.

This paper proposes a novel analytical methodology for soil classification based on the use of laser-induced breakdown spectroscopy (LIBS) and chemometric techniques. In the proposed methodology, linear discriminant analysis (LDA) is employed to build a classification model on the basis of a reduced subset of spectral variables. For the purpose of variable selection, three techniques are considered, namely the successive projection algorithm (SPA), the genetic algorithm (GA), and a stepwise formulation (SW). The use of a data compression procedure in the wavelet domain is also proposed to reduce the computational workload involved in the variable selection process. The methodology is validated in a case study involving the classification of 149 Brazilian soil samples into three different orders (Argissolo, Latossolo and Nitossolo). For means of comparison, soft independent modelling of class analogy (SIMCA) models are also employed. The best discrimination of soil types was attained by SPA-LDA, which achieved an average classification rate of 90% in the validation set and 72% in cross-validation. Moreover, the proposed wavelet compression procedure was found to be of value by providing a 100-fold reduction in computational workload without significantly compromising the classification accuracy of the resulting models.

In Brazil, the production of potted plants in substrates under semi- or protected cultivation is an economically important activity. The substrate nutrient management in potted plant production is not easy, due to non-standardized methods of water extraction for chemical analysis of nutrients that may lead to misinterpretation of nutrient results. The objective of this research was to evaluate current water extraction methods for the chemical analysis of a coir substrate incubated with conventional-NPK and slow-release fertilizers (SRF). Substrate samples were collected at 20, 60 and 120 days after incubation, for the determination of micronutrients using water extraction: 1:1.5; 1:2; 1:5; 1:10; and saturated extract (SE). Cl, B, Cu and Fe concentrations in extracts were not affected by the incubation period, however, Zn and Mn concentrations increased with time. The SE and 1:1.5 extraction methods were the most effective in discriminating differences among fertilization treatments. They resulted in higher values for Cl, Fe, Mn and Zn, than any of the water extracts. They were good for the evaluation of Cu concentration in fertilized coir substrate.

Este trabalho foi desenvolvido com o objetivo de estudar o efeito das polpas de frutas no crescimento de plântulas de orquídeas in vitro. Três espécies de orquídeas epífitas brasileiras foram usadas: Laelia longipes Rchb.f., Laelia tenebrosa Rolfe e Miltonia spectabilis (Lindley). Os seguintes meios nutritivos foram testados: 10:10:10 (N:P:K), na concentração de 1 g L-1, 10:30:20, 1 g L-1, polpa de maçã, 10,0 g L-1, polpa de tomate, 10 g L-1, polpa de banana, 50 g L-1, e também os meios de KNUDSON, VACIN e WENT, MURASHIGE e SKOOG. Nas plântulas de L. longipes, cultivadas em 10:10:10 e polpa de banana observou-se o maior acúmulo de, massa e naquelas cultivadas em MS o menor. Pela análise dos resultados para Miltonia spectabilis observou-se que os meios 10:30:20 e polpa de banana proporcionaram o maior acúmulo de massa seca e no meio MS, o menor acúmulo. Em ordem decrescente de acúmulo de matéria seca total estão os meios 10:30:20 e polpa de banana, seguidos por 10:10:10, polpa de tomate, KNUDSON (58,3%), VACIN e WENT (18,7%), polpa de maçã (13,2%) e MS (4,1%). Para Laelia tenebrosa, as plântulas cultivadas no meio polpa de banana incorporaram o maior conteúdo de matéria seca, seguidas pelas plântulas cultivadas em meio com 10:10:10. Os outros meios propiciaram acúmulo reduzido.