Cristiane de Conti Medina

Método do Perfil Cultural para avaliação do estado físico de solos em condições tropicais

A new approach is discussed for adoption of criteria in the application of the cultural profile methodology for tropical soil conditions. The evolution of this methodology has been analyzed since its beginning in France in the 1960s, until its proposal for tropical soil management studies. The cultural profile approach can be used to make qualitative diagnosis of the physical state of soil in the field, as well as to help with soil sampling, to study the effect of agricultural machinery, to visualize the physical, chemical and biological soil interactions, and to help with the studies of contraction, expansion, and shearing in the field and in the structural organization of soils and root system analyses.

Soil physical properties and sugarcane root growth in a red oxiso

Sugarcane, which involves the use of agricultural machinery in all crop stages, from soil preparation to harvest, is currently one of the most relevant crops for agribusiness in Brazil. The purpose of this study was to investigate soil physical properties and root growth in a eutroferric red Oxisol (Latossolo Vermelho eutroferrico) after different periods under sugarcane. The study was carried out in a cane plantation in Rolândia, Parana State, where treatments consisted of a number of cuts (1, 3, 8, 10 and 16), harvested as green and burned sugarcane, at which soil bulk density, macro and microporosity, penetration resistance, as well as root length, density and area were determined. Results showed that sugarcane management practices lead to alterations in soil penetration resistance, bulk density and porosity, compared to native forest soil. These alterations in soil physical characteristics impede the full growth of the sugarcane root system beneath 10 cm, in all growing seasons analyzed.

INFLUENCE OF SEEDLING PRODUCTION METHOD ON THE ROOT SYSTEM DISTRIBUTION OF BLACK WATTLE TREES

The purpose of this study was to evaluate the root system distribution of three-year-old black wattle (Acacia mearnsii) trees. The plants were originated from seedlings grown in different containers and planted in an Argisol in the state of Rio Grande do Sul, Brazil. The containers used for seedling production were: wood laminated pots, round plastic tubettes and styrofoam trays. The evaluations were carried out using the trench profile method up to 1 m depth on tree rows and inter-rows. The following soil analyses were also carried out: bulk density, total porosity and pore distribution. The type of container used influenced the development of the root system of trees on the field. Wood laminated pots were better than the round tubettes for root length in the tree rows. The roots developed better on the tree rows where soil density and porosity conditions were more adequate.

Matéria seca, carbono e nitrogênio de raízes de soja e milho em plantio direto e convencional

The objective of this work was to examine whether soil tillage systems affect the distribution and accumulation of dry matter (DM), carbon (C) and nitrogen (N) of root systems of soybean (Glycine max) and corn (Zea mays) in a clayey Typic Haplorthox. Volumetric rings were used for root sampling down to 1 m depth. The distribution in depth and accumulation of DM, C and N of soybean and corn roots were not affected by soil tillage systems. Root length density was 0.7-1.4 cm cm-3 for soybean and 1.2-1.6 cm cm-3 for corn in the 0-0.10 m layer and decreased in the other layers. Root DM input was 1.94-2.01 Mg ha-1 in soybean and 2.50-3.79 Mg ha-1 in corn. For soybean, C and N root inputs were 0.61-0.63 Mg ha-1 and 36.9-38.2 kg ha-1, respectively. For corn, C and N root inputs were 0.72-1.10 Mg ha-1 and 18.78-28.48 kg ha-1, respectively. Independently of the tillage system, 80% of the roots were concentrated in the upper surface layer 0.43 to 0.54 m deep for soybean and in the upper surface layer 0.40 to 0.46 m deep for corn.

Produtividade e índices biométricos e fisiológicos de cana‑de‑açúcar cultivada sob diferentes quantidades de palhada

The objective of this work was to evaluate the effect of different amounts of straw mulch on the biometric and physiological indices and on the yield of the sugarcane variety SP 801816, in the first crop cycle (plant cane). Five treatments - with 0, 25, 50, 75, and 100% straw mulch - were evaluated at 60, 180, 270, and 350 days after planting. The following biometric indices were determined: leaf area, number of leaves, fresh matter weight, and number of tillers. The physiological indices were: leaf area index (LAI), crop growth rate (CGR), and relative growth rate (RGR). A significant effect of straw mulch was observed on all variables. Treatments with 100, 75, and 50% straw provided the highest values for LAI, CGR, RGR, and number of tillers, and the treatments with 50 and 75% straw provided the highest yields. Keeping straw mulch at the soil surface had no effect detrimental to sugarcane development. Total removal or straw kept at 25% resulted in the lowest yields. Removal of 50% straw can be done without harming the crop.

Comparison of citrus rooting evaluation methods using root images in soil profiles and root weight

Com o objetivo de comparar metodos de estudo do sistema radicular em citros, foram tomadas, em video, imagens de raizes situadas em um perfil de solo, e as mesmas raizes foram coletadas e pesadas. As raizes presentes nas imagens foram quantificadas (comprimento e area) por meio do programa SIARCS, desenvolvido pela Embrapa. A area do perfil analisada foi delimitada por aneis de ferro, que tambem foram utilizados para retirar as raizes para a determinacao do peso seco. O comprimento e a area de raizes, determinados por imagens digitalizadas, forneceram uma boa estimativa da quantidade de raizes presentes no perfil.

Mulching with Sugarcane Straw Reduces Weed Density in Sugarcane Field

Occurrence of weeds in sugarcane crop according to levels of straw over the soil was studied. Experiment was carried out during two annual cycles. Treatments were 0 % (no straw); 25, 50, 75 and 100% (i.e., 5, 10, 15 and 20 t/ha of straw, respectively); and straw burned over the soil. Floristic analysis of weed species was achieved. Percent area occupied by weeds was assessed visually and regression analysis between weeds and amount of straw mulch was performed. Floristic analysis characterized 19 weed species, from eight botanical families: Amaranthaceae, Asteraceae, Commelinaceae, Convolvulaceae, Euphorbiaceae, Poaceae, Portulacaceae and Solanaceae. Highest richness of species was observed for Asteraceae and Poaceae, with seven and four species, respectively. Higher frequency was found for Amaranthus hybridus, A. viridis and Physalis angulata (85% of samples) for first annual crop cycle; and A. hybridus, Bidens pilosa and Cenchrus echinatus predominated (83% of samples) in second cycle. A. hybridus was the most frequent species in both cycles. The highest density of weeds was observed in treatments with straw burned. Application of 75 and 100% straw showed highest suppression for low and high density of weeds, respectively. Increasing level of straw leads correspondent weed control. That information is vital to orientate decision which amount will deposit over the soil since in recent years the straw is also demanded for alternative sources of energy, as thermal or second generation bio-ethanol.

Influence of irrigation on wheat crop

O uso da irrigacao na triticultura tem aumentado significativamente nos ultimos anos no Brasil. Neste trabalho, objetivou-se avaliar a influencia da irrigacao na produtividade, na qualidade tecnologica da farinha e no sistema radicular do trigo. Em experimento de campo no IAPAR, em Londrina, Parana, a cultivar IPR 118 foi cultivada sob irrigacao por aspersao convencional (Tratamento Irrigado) e sem irrigacao (Tratamento Sequeiro). A produtividade foi determinada, colhendo-se tres amostras de 25 m2 por tratamento. Nestas mesmas amostras, procedeu-se a analise da qualidade tecnologica da farinha, sendo avaliada, entre outros parâmetros, a forca de gluten (W). A avaliacao do sistema radicular foi realizada apos a colheita, no perfil de 0 a 45 cm de profundidade do solo, amostrando-se oito plantas em cada tratamento. O metodo da parede do perfil foi utilizado para determinar o numero de raizes (NR) e o metodo do monolito para determinar a massa seca de raizes (MSR). A irrigacao aumentou em tres vezes a produtividade do trigo, porem diminuiu o W na farinha. Ainda assim, o valor de W encontrado no Tratamento Irrigado (249 10-4 J) foi suficiente para manter a classificacao do trigo como tipo-pao, a mesma para o qual a cultivar IPR 118 e classificada. Os valores medidos de NR e a MSR foram iguais ou maiores no Tratamento Sequeiro.