Caetano Marciano de Souza

Fitorremediação de solos contaminados com herbicidas

A fitorremediacao e uma tecnica que objetiva a descontaminacao de solo e agua, utilizando-se como agente de descontaminacao plantas. E uma alternativa aos metodos convencionais de bombeamento e tratamento da agua, ou remocao fisica da camada contaminada de solo, sendo vantajosa principalmente por apresentar potencial para tratamento in situ e ser economicamente viavel. Alem disso, apos extrair o contaminante do solo, a planta armazena-o para tratamento subsequente, quando necessario, ou mesmo metaboliza-o, podendo, em alguns casos, transforma-lo em produtos menos toxicos ou mesmo inocuos. A fitorremediacao pode ser empregada em solos contaminados por substâncias inorgânicas e/ou orgânicas. Resultados promissores de fitorremediacao ja foram obtidos para metais pesados, hidrocarbonetos de petroleo, agrotoxicos, explosivos, solventes clorados e subprodutos toxicos da industria. A fitorremediacao de herbicidas apresenta bons resultados para atrazine, tendo a especie Kochia scoparia revelado potencial rizosferico para fitoestimular a degradacao dessa molecula. Embora ainda incipiente no Brasil, ja existem estudos sobre algumas especies agricolas cultivadas e especies silvestres ou nativas da propria area contaminada, com o objetivo de selecionar especies eficientes na fitorremediacao do solo.Phytoremediation is a technique that uses plants as agents of soil and water decontamination. It is an advantageous alternative to the conventional methods of water pumping and treatment and/or physical removal of the contaminated soil layer since it allows in situ treatment at feasible costs. Also, after extracting the contaminant from the soil, the plant stores it for a subsequent treatment, if necessary, or may metabolically transform it into products that are less or non-toxic. Phytoremediation can be employed in soils contaminated by inorganic or organic substances. Promising phytoremediation results have been obtained in soils contaminated by heavy metals, petroleum hydrocarbons, pesticides, explosives, chlorinated solvents and toxic industrial by-products. Herbicide phytoremediation presents interesting results for atrazine, with Kochia scoparia species revealing rhizospheric potential for phytostimulating molecule degradation. Although this technique is not well known in Brazil, studies have been performed using agricultural crops and wild or native plant species from contaminated areas to select efficient species for soil phytoremediation.

Sistemas de preparo do solo para o cultivo do milho safrinha

This study was carried out at the Coimbra Experiment Station, of Federal University of Vicosa, State of Minas Gerais, Brazil, on a long-term field experiment initiated in October 1995 and to be terminated in 2006. The evaluations were made in 1997 using the safrinha corn (fall cropping) produced in an area where bean (October cropping) had been previously grown, in order to evaluate the effects of no-till (SD), mold-board plow (AA), disk plow (AD), heavy offset disk harrow (GP) and rotary hoe (ER) on corn yield. The no-till system resulted in plants with fewer days to flowering but with higher values for: stem diameter, height of insertion, planting height, number of ears per hectare, number of plants per hectare first ear, average ear production, ear index and grain yield.

Seleção de plantas com potencial para fitorremediação de tebuthiuron

This study aimed to select tebuthiuron- tolerant plants to use them in phytoremediation programs in contaminated soils. The evaluated species were: Amaranthus hybridus, Crotalaria juncea, C. hyssopifolia, Chamaesyce hirta, Canavalia ensiformes, Helianthus annus, Pennisetum typhoides, Estizolobium aterrimum, Raphanus raphanistrum and Crotalaria incana. The experiment was carried out in a greenhouse, with a sandy-clay soil with 2.18 dag kg-1 of organic matter, in pots of 3 dm3 capacity. The experiment was arranged in a 10 x 4 x 4 factorial scheme in a randomized block design with three replications. The treatments consisted of: 10 species, four tebuthiuron doses (0.0; 0.5; 1.0 e 2.0 kg ha-1) applied in pre-emergence, and four evaluation times (15, 30, 45, and 60 days after sowing). Phytotoxicity, plant height and, above-ground, root and total biomass dry matter were evaluated. Canavalia ensiformes and Pennisetum typhoides were tolerant to tebuthiuron at the dose of 0.5 kg ha-1, and Estizolobium aterrimum up to the dose of 1.0 kg ha-1, with the latter showing less phytotoxicity symptoms and a smaller reduction of plant height, above-ground, root, and total biomass dry matter, as compared to the control treatment.

Inferências sobre atividade rizosférica de espécies com potencial para fitorremediação do herbicida tebuthiuron

SUMMARY : RHIZOSPHERIC ACTIVITY OF POTENTIALLY PHYTOREME-DIATIVE SPECIES FOR TEBUTHIURON-CONTAMINATEDSOIL The rhizospheric microbial action, accelerating the degradation of compounds in thesoil, is known as phytostimulation. It represents one of the main phytoremediationmechanisms in herbicide-contaminated soil. Tebuthiuron-tolerant plants, which are ableto stimulate their rhizospheric microorganisms, could be highly interesting for thephytoremediation of this herbicide. This study aimed at evaluating the rhizospheric activityof four plant species with phytoremediation potential for tebuthiuron and to infer on thecontribution of the roots to the process of decontamination of this herbicide. The rhizosphericsoil of jackbean ( Canavalia ensiformis ), pearl millet ( Pennisetum glaucum ), Georgia velvetbean (S tizolobium deeringianum ), and black velvet bean ( Stizolobium aterrimum ), plus acontrol treatment (without plant) were analyzed without and with tebuthiuron at 0.73 ig g -1 .The CO

Desempenho de uma semeadora-adubadora para plantio direto, em dois solos com diferentes tipos de cobertura vegetal

O desempenho operacional de uma semeadora-adubadora de plantio direto, versao soja e milho, foi avaliado em um Podzolico Vermelho-Amarelo câmbico, fase terraco, e um Latossolo Vermelho-Amarelo, da Zona da Mata de Minas Gerais. A maquina foi testada em tres tipos de cobertura do solo e em duas velocidades de trabalho. Por ocasiao do plantio, foram avaliados a patinagem do trator e da semeadora-adubadora, o consumo de combustivel e a potencia exigida, a distribuicao de fertilizante e o nivel de danos as sementes. Depois do plantio, foram avaliados o numero de sementes distribuidas, o estande final, a profundidade de plantio e a distribuicao longitudinal da semente. A uniformidade de distribuicao longitudinal foi avaliada pela porcentagem de espacamentos aceitaveis, distribuicao dupla e falhas na distribuicao, e pelo coeficiente de variacao dos espacamentos entre sementes. A demanda de potencia foi maior no Podzolico, por sua maior densidade e resistencia a penetracao. Independentemente do tratamento, o numero de sementes distribuidas e o estande final nao apresentaram diferencas significativas. As sementes distribuidas nao tiveram sua qualidade afetada pelos dosadores da maquina. A analise de variância nao indicou diferenca significativa entre os porcentuais de espacamentos aceitaveis, a distribuicao dupla e as falhas.

Aspectos fitossociológicos da comunidade de plantas daninhas na cultura do feijão sob diferentes sistemas de preparo do solo

Tillage systems change the floral composition of a weed community. The changes can be either a simple fluctuation in plant population or the establishment of a permanent new weed community, affecting competition, management and control. The aim of this work was to evaluate the effects of tillage systems on the weed community in bean crop in areas where different tillage systems were being applied since 1985.The experimental soil was cultivated with annual cultures and submitted to six tillage systems: no-tillage (PD), moilboard plow (AD), plow of disc (AA), heavy bars (GA), heavy bars + moilboard plow (GA+AD) and heavy bars + plow of disc (GA+AA). The results discussed in this work are related to the 2001 winter-spring crop season only. The plots were divided in two sub-plots, and submitted or not to treatment with post-emergence herbicide, resulting in a complete randomized block design with four replications. The weeds were grouped by species, classified, dried and weighed. Total dry biomass and density of the weeds were submitted to the Tukey test. The weed species were analyzed according to their relative importance in the weed community, taking into account the phytosociological indices of density, frequency and dominance. Herbicide application in post-emergence reduced the total biomass of the weeds. Herbicide effect was independent of the soil tillage systems used. The soil tillage systems and herbicide application in post-emergence modified the relative importance of the weed species in the community. The species showing higher relative importance were Cyperus rotundus, in the treatments under conventional soil preparation, and Galinsoga parviflora, under no-tillage, mainly where the herbicide was applied in post-emergence.

Variação dos valores de pH e dos teores de carbono orgânico, cobre, manganês, zinco e ferro em profundidade em Argissolo Vermelho-Amarelo, sob diferentes sistemas de preparo de solo

No-till has been adopted more and more by farmers and research has generated much information on nutritional aspects, mainly related to organic matter, nutrients accumulation, especially macronutrients, and soil acidity. However, there is a lack of information on micronutrient dynamics in this tillage system. In an experiment installed fifteen years ago on an Ultisol (Argissolo Vermelho-Amarelo) soil samples were collected to evaluate the influence of six soil tillage systems: no-till (SD), moldboard plow (AA), disk plow (AD), tandem-heavy disk plow (GP), tandem-heavy disk plow + moldboard plow (GP+AA) and tandem-heavy disk plow + disk plow (GP+AD), on pH values and contents of organic carbon and micronutrients copper, manganese, zinc and iron in four depths (0-2.5; 2.5-5.0; 5.0-10.0 and 10.0-20.0 cm). Differences were observed for values of pH and contents of organic carbon, copper, manganese and zinc for tillage systems and soil depths, with the largest values being observed in the first 5 cm of soil depth under the SD system. Below the depth of 5 cm more similarity for the studied treatments was observed, with greater content reductions in the layer from 10 to 20 cm. Iron contents was negatively influenced by the organic matter in surface in SD and GP systems. Micronutrient contents correlated positively with organic carbon contents in the different tillage systems and depths. The treatments that involved greater soil turn-over showed larger homogeneity on organic matter and micronutrient contents along the sampled profile.

Influência da cobertura morta na umidade, incidência de plantas daninhas e de broca-do-rizoma (Cosmopolites sordidus) em um pomar de bananeiras (Musa spp.)

Brazil possesses the largest harvest area of banana in the world, however it just occupies the second placement in the world ranking of the largest producers. For this reason, handling techniques should be used purposing to increase the productivity. This work aimed to evaluate the effects of mulching on humidity, weeds and Cosmopolites sordidus in a banana orchard managed with mulching and without mulching. The analysis and interpretation of results showed that the mulching presented benefits related to the soil humidity maintenance and weeds control, and the incidence of the Cosmopolites sordidus did not show any difference compared with the maintained area without mulching.

Teor de água e fertilidade do solo com cafeeiros cultivados em sistemas agroflorestais

The aim of this study was to compare the soil moisture and fertility in coffee systems intercropped with trees with low levels of fertilization and in conventional system; the following systems were tested: coffee (Coffea arabica L.) under full light; coffee with Senna macranthera; coffee with Senna macranthera and Musa sp.; coffee with Senna macranthera, Musa sp. and Zeyhera tuberculosa. The last three systems were evaluated with the same density of intercropped plants and all treatments with the same number of coffee plants. The trial was conducted during a 57-month period. A favorable balance for water conservation in the soil was obtained in the intercropped system at the beginning of the dry season. However, the maintenance of this balance will depend on the water demand of the components of the intercropped system and the dry season duration. The intercropped system favored pH stability and reduction in aluminum saturation, nevertheless the nutrient requirement of the components of the intercropped system should be supplied by means of external inputs, to avoid soil impoverishment.

Population density and weed infestation in organic no-tillage corn cropping system under different soil covers

Currently, one of the biggest challenges faced by organic no-tillage farming is weed control. Thus, the use of cropping practices that help in the control of weeds is extremely important. The objective of this study was to evaluate population density and level of weed infestation in an organic no-tillage corn cropping system under different soil covers. The experiment was conducted in a randomized block design with six repetitions and five treatments, consisting of three soil covers in an organic no-tillage system, and an organic and a conventional system, both without soil cover. The treatments with soil cover used a grass species represented by the black oat, a leguminous species represented by the white lupine, and intercropping between both species. Corn was sown with spacing of 1.0 m between rows and 0.20 m between plants, using the commercial hybrid AG 1051. Infestation in corn was evaluated at stages V5 and V10, and weed density was evaluated at stage V5. The use of black oat straw alone or intercropped with white lupine, in the organic no-tillage corn cropping system, reduced the percentage of weed infestation and absolute weed density. Management-intensive systems and systems without soil cover showed higher relative densities for species Oxalis spp., Galinsoga quadriradiata and Stachys arvensis. The species Cyperus rotundus showed the highest relative density on organic no-tillage corn cropping systems. Black oat straw in the organic no-tillage cropping system limited the productive potential of corn.