Lúcio José Vivaldi

Adubação nitrogenada em capim-coastcross: efeitos na extração de nutrientes e recuperação aparente do nitrogênio

Foi conduzido experimento em Latossolo Vermelho Distrofico tipico, em Sao Carlos, SP, para avaliar o efeito de doses e fontes de nitrogenio (N), no teor, extracao dos nutrientes e na recuperacao do N aplicado em capim-coastcross (Cynodon dactylon cv. Coastcross). Foram aplicadas sobre a superficie do solo cinco doses de N (0, 25, 50, 100 e 200 kg ha-1corte-1), na forma de ureia ou de nitrato de amonio, em cinco periodos consecutivos, durante a estacao chuvosa. Foram determinados os teores e calculada a extracao de nutrientes e a recuperacao do N. Houve aumento na extracao dos nutrientes com o aumento da producao de forragem, com elevados valores principalmente para N e K. Para altas producoes de forragem (tratamento 500 kg ha-1 ano-1de N) e para as duas fontes de nitrogenio as extracoes dos macronutrientes foram maiores para K e N, seguidas de Ca, S, P e Mg e dos micronutrientes Fe, Mn, Zn e Cu. A recuperacao media de N da ureia foi de 68% do N obtido do nitrato de amonio, que variou, em media, de 68 a 75%.

Cover plants with potential use for crop-livestock integrated systems in the Cerrado region

The objective of this work was to evaluate the effects of lignin, hemicellulose, and cellulose concentrations in the decomposition process of cover plant residues with potential use in no-tillage with corn, for crop-livestock integrated system, in the Cerrado region. The experiment was carried out at Embrapa Cerrados, in Planaltina, DF, Brazil in a split plot experimental design. The plots were represented by the plant species and the subplots by harvesting times, with three replicates. The cover plants Urochloa ruziziensis, Canavalia brasiliensis, Cajanus cajan, Pennisetum glaucum, Mucuna aterrima, Raphanus sativus, Sorghum bicolor were evaluated together with spontaneous plants in the fallow. Cover plants with lower lignin concentrations and, consequently, higher residue decomposition such as C. brasiliensis and U. ruziziensis promoted higher corn yield. High concentrations of lignin inhibit plant residue decomposition and this is favorable for the soil cover. Lower concentrations of lignin result in accelerated plant decomposition, more efficient nutrient cycling, and higher corn yield.

Indicadores biológicos associados ao ciclo do fósforo em solos de Cerrado sob plantio direto e plantio convencional

The objective of this work was to evaluate the effects of no-till, conventional tillage and cover crops on biological indicators associated to the P cycle. The work was carried out on three adjacent areas on a Red- Yellow Oxisol: area I, a two-year experiment comparing the two management systems; area II, a six-year experiment, and area III, a native Cerrado vegetation. The soil was sampled at two depths (0-5 cm and 5-20 cm) in July/1998 and January/1999. The biological indicators evaluated were microbial biomass P, acid phosphatase activity, phosphate-solubilizing and total soil fungi and bacteria. Acid phosphatase activity and number of phosphate- solubilizing microorganisms, at the 0-5 cm depth, were significantly greater in the no-till soil, as compared to the conventional tillage. Differences between the tillage systems, regarding the biological indicators evaluated, were more pronounced in area II in which the no-till system had been established for a longer period. Microbial P decreased in the no-till Raphanus sativus treatment. P-solubilizing fungi increased in the presence of Cajanus cajan and Raphanus sativus, whereas the P-solubilizing bacteria increased in the presence of C. cajan. Highest activities of acid phosphatase were detected in the soil under native vegetation, evidencing the importance of organic P mineralization in this ecosystem.

Assessment of nutrient and water intake among adolescents from sports federations in the Federal District, Brazil

Adolescents aged 11-14 years (n 326), belonging to organized sports federations in the Federal District, Brazil were interviewed. Subjects (n 107) provided four non-consecutive days of food consumption and 219 subjects provided two non-consecutive days of intake. The objective was to assess their nutrient and water intake according to dietary reference intake values and their energy and macronutrient intake by sex and sports groups they were engaged in: endurance, strength-skill or mixed, according to the guidelines established by the American College of Sport Medicine (ACSM). Dietary data were corrected for intra-individual variation. Total energy expenditure was higher among endurance athletes (P < 0.001) following their higher training time (P < 0.001) when compared to adolescents engaged in strength-skill or mixed sports. Total energy intake was only significantly higher among endurance-engaged females (P = 0.05). Protein intake of males was above the guidelines established by the ACSM for all sports groups. All male sport groups fulfilled the intake levels of carbohydrate per kg body weight but only females engaged in endurance sports fulfilled carbohydrate guidelines. Intakes of micronutrients with low prevalence of adequate intake were: vitamins B1, E and folate, magnesium and phosphorus. Few adolescents ( < 5 %) presented adequate intake for calcium, fibre, drinking water and beverages. For micronutrients, prevalence of adequacies were lower for females than males, except for liquids and water. Nutrition guidance is needed to help adolescents fulfil specific guidelines of macronutrient intake for their sports and to improve their intake of micronutrients and water. Special attention should be given to female adolescent athletes.

Impacto da invasão e do manejo do capim-gordura (Melinis minutiflora) sobre a riqueza e biomassa da flora nativa do Cerrado sentido restrito

No Brasil, varias especies de gramineas sao citadas como invasoras em Unidades de Conservacao. Contudo, ainda se conhece muito pouco sobre o impacto do estabelecimento e da colonizacao dessas especies nas areas protegidas. Entre as gramineas exoticas introduzidas no bioma Cerrado merece destaque a especie africana Melinis minutiflora P. Beauv., o capim-gordura. O presente estudo objetivou avaliar o impacto desta invasora na biomassa e na riqueza da comunidade nativa em uma area de Cerrado Ralo invadido, como tambem estudar a dinâmica da vegetacao do estrato rasteiro submetida a aplicacao de diferentes tecnicas de manejo para o controle do capim-gordura. Os resultados mostraram que, na area experimental, onde o capim-gordura representa cerca 62% da biomassa total do estrato rasteiro, o numero de especies nativas encontradas foi alto. Nas areas onde o capim-gordura apresentou alto indice de colonizacao (> 98%), sua biomassa alcancou cerca de duas vezes a biomassa do estrato rasteiro registrada para o Cerrado. A realizacao de uma queimada nao foi suficiente para controlar o capim-gordura, porque apos tres anos a sua biomassa se aproximou aos valores encontrados inicialmente. Por outro lado, no tratamento manejo integrado (maio ou setembro) a reducao de mais de 99,9% na sua presenca favoreceu a expansao da vegetacao nativa, configurando-se, assim, uma estrategia promissora para a recuperacao ambiental das areas invadidas pelo capim-gordura no Cerrado.

Two-stage inference in experimental design using dea: an application to intercropping and evidence from randomization theory

In this article we propose the use of Data Envelopment Analysis (DEA) measures of efficiency, under constant returns to scale and input equal to unity, in the analysis of multidimensional nonnegative responses in the design of experiments. The approach agrees with the standard Analysis of Variance (Covariance) for univariate responses and simplifies the statistical analysis in the multivariate case. The best treatments provided by the analysis optimize a combined output defined by shadow prices, which are the solutions of the DEA problem. The approach is particularly useful for the analysis of intercropping (crop mixtures) experiments. In this context we discuss two examples. To properly address the issue of correlation and non-normality of DEA measurements in different experimental plots we validate the results via Randomization Theory.

Seleção de matrizes e clones de mangabeira para o cultivo in vitro

High tax of mortality of mangabeira (Hancornia speciosa) seedlings in greenhouse conditions hinders its use on the reversion of the degradation of the natural vegetation, as well as on the preservation of the production and environmental integrity. The objective of this work was to select better mother plants and clones from sexual and assexual propagation, with potential to survive in vitro, for producing mangaba seedlings. Fruits were collected from 11 mother plants and from each plant, 24 seeds without aparent diseases were selected. After superficial desinfection, seeds were inoculated in MS medium without growth regulators and having a germination of 92.4% without significant difference between mother plants. On multiplication phase, with MS medium, with growth regulators BAP (6-benzilaminopurine) and IBA (indol-3-butiric acid), both at concentration of 1.28 mg L-1; the better mother plant was C1 and better clone was C1 15. During all phases of this work there was a high variability, mainly among clones. The selection must be made mainly among clones in mother plants.

Adubação de aveia em dois sistemas de plantio

The objective of this work was to determine the best rates of N, P, and K to obtain maximum economic return per area of forage yield for the oat line UPF 87111 grown in two planting systems i.e conventional tillage and with a corn-residue mulch. The experiments were carried out in a Dark-Red Latosol (Hapludox). The experimental design was a incomplete (1/2)4 3 factorial, with two randomized blocks, with a total of 32 plots, without replication. The treatments comprised four rates of N and K2O (0, 70, 140, and 210 kg ha -1 ), using urea and potassium chloride, respectively, and four rates of P2O5 (0, 60, 120 and 180 kg ha -1 ), using triple superphosphate. The N, P, K rates for maximum profit were, in kg ha -1 for conventional tillage: N = 165, P2O5 = 50, K2O = 53; and for mulch-covered field: N = 210, P2O5 = 90, resulting in forage yields of, respectively, 6,641 and 7,322 kg ha -1 of dry matter. In both planting systems there was response only to N, and its use resulted in higher forage yield per unit of applied fertilizer.

Características morfológicas do Paspalum atratum cv. Pojuca submetido ao pastejo rotacionado. Dinâmica de perfilhamento e elongação de folhas

This experiment was conducted at the Brasilia Agricultural College - Federal District, and studied the dynamics of appearance and death of tillers as well as leaf elongation in three positions of the stump (central, intermediate and peripheral) of Paspalum atratum cv. Pojuca, submitted to four rotational grazing cycle of 10 days use and 30 days resting. A descriptive analysis was applied using a hierarchical model. Nitrogen was applied at a rate of 40 kg/ha, in the form of ammonium sulfate before each grazing cycle. The area was divided in two sets of four pickets of 0.4 ha each and two other areas of about 6 m2 used as a reference for the purpose of quantifying the effect of grazing. The tillers were counted in 120 squares with 0.25 m2 area distributed in the eight pickets and the other eight in the non grazed areas. The highest tillering occurred during cycle 2, coinciding with the highest precipitation. The species showed a low level of tiller death during the studied period. Grazing did not reduce the tillering during the vegetative growth phase. Leaf elongation had its highest values in cycles 1 and 2 and lowest in cycles 3 and 4. The highest elongations occurred in the periferic and middle positions and the lowest in the central position of the stump.