Ideal desiccation periods of Urochloa ruziziensis for a no-till sunflower crop

Sowing crops following cover crops on forage may cause injuries and productivity reduction, due reasons as allelopathy or glyphosate residues. The objective of this study was to evaluate the influence of differing periods between cover crop (Urochloa ruziziensis) desiccation with glyphosate and sunflower (Aguara 4) sowing in a no-tillage system on crop development and productivity. Two assays were performed in two seasons, one in pots and the other in a field. Treatments in field assay consisted on 5 desiccation times of U. ruziziensis (with an application of glyphosate at 1.08 kg ae ha(-1)) preceding the sowing of no-till sunflower (0, 3, 7, 10 and 30 days). At the pot assays, 6 times were studied: 0, 3, 7, 10, 15 and 20 days between cover crop desiccation and sunflower sowing. A control without cover crop was also included in this assay. Biometric evaluations were performed at the vegetative stage and at harvest. As the period between U. ruziziensis desiccation and sunflower sowing was shortened, achene production in sunflower was exponentially reduced. Glyphosate application at 3 or 0 days pre sowing diminished sunflower development and achene production by approximately 30% compared to desiccation periods greater than 7 days.

Analysis of the radial operation of distribution systems considering operation with minimal losses

Electric power distribution systems, and particularly those with overhead circuits, operate radially but as the topology of the systems is meshed, therefore a set of circuits needs to be disconnected. In this context the problem of optimal reconfiguration of a distribution system is formulated with the goal of finding a radial topology for the operation of the system. This paper utilizes experimental tests and preliminary theoretical analysis to show that radial topology is one of the worst topologies to use if the goal is to minimize power losses in a power distribution system. For this reason, it is important to initiate a theoretical and practical discussion on whether it is worthwhile to operate a distribution system in a radial form. This topic is becoming increasingly important within the modern operation of electrical systems, which requires them to operate as efficiently as possible, utilizing all available resources to improve and optimize the operation of electric power systems. Experimental tests demonstrate the importance of this issue. (C) 2014 Elsevier Ltd. All rights reserved.

Sistemas de cultivo antecessores e doses de nitrogênio em cobertura no feijoeiro em plantio direto = cover crop systems and nitrogen topdressing on common bean in no tillage

The objective of this work was to evaluate the grass cover crop production in crop systems involving maize and Urochloa ruziziensis, and the influence of topdressing nitrogen rates in the yield and agronomic efficiency on common-bean cultivated in succession in no-tillage. The experiments were conducted in Jaboticabal-SP, in a eutrophic red latosol, in the second year of no-tillage system implementation. The IPR 139 cultivar was used in split plot design with three replications, in randomized block. The plots had been composed for three crop systems in the summer season, with maize exclusive, maize intercropped with U. ruziziensis and U. ruziziensis exclusive. The subplots had been constituted for five nitrogen rates (0, 40, 80, 120 and 160 kg ha(-1)), applied as topdressing at V4-4 in irrigated common-bean cultivated in the winter-spring season. The use of U. ruziziensis in crops systems, exclusive or intercropped with maize favors the grass cover crop production sufficiently to total soli surface covered, possibility similar grain yield compared to maize exclusive. The topdressing nitrogen application doesn't affect the common-bean yield in succession to maize and U. ruziziensis intercropped. The increase of nitrogen rates in common-bean in succession to maize exclusive improves the yield, although decreases the agronomic efficiency.

Nutrient cycling in two south-east Brazilian forests. I. Litterfall and litter standing crop

Examined litterfall and litter standing crops in Altitudinal forest (AF and Semideciduous forest (SF) at Serra do Japi, Jundiai, Sao Paulo State. Total litterfall was 7 t ha-1 y-1 for AF: 4.9 leaves, 1.8 woody, 0.13 flower, 0.16 fruits; and the total for SF was 8.6 t ha-1 y-1; 5.5 leaves, 2.1 woody, 0.5 flower, 0.4 fruits. Litter standing crop was 5.5 t ha-1 y-1 for the two forest sites studied with a turnover coefficient (K1) of 1.3 for AF and 1.6 for SF. Litterfall occurred throughout the year but was greater during the dry season (August-September); seasonality of litter and leaf fall was greater in SF than in AF. -from Author

Socio-eco-efficiency of integrated and non-integrated systems of crop, forestry and livestock in the Ipameri city, at brazilian Cerrado

Pós-graduação em Ciências Ambientais - Sorocaba

Ciclagem do nitrogênio relacionada ao sistema de produção

Pós-graduação em Agronomia (Agricultura) - FCA

Ammonia volatilization losses in Tanzania grass fertilized with urea

Gaseous losses are the main factors affecting the efficiency of nitrogenous fertilizers in pastures. To evaluate NH3-N volatilization losses in Tanzania grass fertilized with urea in autumn, spring and summer, a completely randomized design with repeated measurements over time and fifteen replicates was used. Plots were represented by urea levels (50; 100 and 150 kg ha-1 N) and subplots by time after fertilization (1; 2; 3; 6; 9; 12 and 15 days). The interaction between fertilization leveland time after urea application was significant for the accumulated NH3-N volatilization. Urea application leads to higher percentage N losses in the first three days after application. The average cumulative NH3- N loss for the three occasions (different seasons of the year) was 28%, 20% and 16% of N applied for fertilizer doses of 50; 100 and 150 kg ha-1 of N, respectively. The season of the year influenced NH3-N loss pattern and volume, with the lowest values recorded in spring, followed by summer and autumn. The cumulative NH3-N volatilization loss varies from 78 to 90% up to the third day after application of the total NNH3 loss.

Greenhouse gas balance associated with sugarcane production in South-Central Brazil, considering the management and expansion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Qualidade dos processos mecanizados de semeadura e colheita na cultura da soja

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Fertilizantes e sistemas de irrigação: emissões de gases de efeito estufa no cultivo do milho

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Metaheuristics for a crop rotation problem

This paper presents a mathematical model adapted from literature for the crop rotation problem with demand constraints (CRP-D). The main aim of the present work is to study metaheuristics and their performance in a real context. The proposed algorithms for solution of the CRP-D are a genetic algorithm, a simulated annealing and hybrid approaches: a genetic algorithm with simulated annealing and a genetic algorithm with local search algorithm. A new constructive heuristic was also developed to provide initial solutions for the metaheuristics. Computational experiments were performed using a real planting area and semi-randomly generated instances created by varying the number, positions and dimensions of the lots. The computational results showed that these algorithms determined good feasible solutions in a short computing time as compared with the time spent to get optimal solutions, thus proving their efficacy for dealing with this practical application of the CRP-D.

Prevalence of Xanthomonas euvesicatoria on Pepper in Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desempenho efetivo e influência no sistema de limpeza da colheita mecanizada de cana-de-açúcar utilizando diferentes velocidades de deslocamento e rotações do extrator primário

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Lodo de esgoto compostado na produção de tapetes de grama esmeralda e na manutenção de água no solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Morfologia do testículo e espermatogênese em Telchin licus (Drury, 1773) (Lepidoptera: Castiniidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)