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Disinfestation of the substrate is mandatory in the production of healthy and vigorous seedlings. However, conventional treatment with agrochemicals can be unsatisfactory, due to the costs and risks of biological vacuum and intoxication. To minimize these limitations, solarization emerges as a potentially viable technique. Therefore, this work evaluated the energy conversion of a solar collector and its capacity for disinfesting substrate with cricket (Gryllus assimilis (Fabr. 1775)). The equipment was built with a wooden box, with six galvanized steel tubes inside. The face of the box facing the sun had transparent glass, which allowed the entry of shortwave solar radiation and restricted the outflow of hot air masses. A completely randomized experimental design was used, with four solar radiation exposure treatments, each with five replications. During the experiment, it was found that the maximum temperature of the substrate was 70.4 °C, with a maximum thermal amplitude of 38.6 °C, between the interior and exterior of the equipment. The thermal variation, per unit of incident solar radiation, reached a maximum value of 1.61 °C. W-1.m-2. The quickest extermination of the insects occurred with two hours of exposure to solar radiation. The substrate temperatures inside the solar collector and the control, were on average 60.4 and 25.0 °C, respectively. [ABSTRACT FROM AUTHOR]

Biomass ranks third as the greatest energy source for the conversion of electricity in Brazil, with sugarcane as the most relevant energy input. Bagasse is the residual biomass in the crushing process and its storage is required due to the production´s seasonality. Experiments have been undertaken for samples of stocked material in different positions (differentiated degradation) obtained in an agro-industrial unit with seventy thousand tons acquired for use in a steam boiler. Physical and chemical (immediate analysis, including humidity) and energetic (heat power) characteristics of sugarcane bagasse were evaluated when undergoing stocking conditions in the open air during three years. Climate influence and storage conditions were analyzed in alterations of the energy potential of residual biomass. The following results are underscored: a) specific mass was four times higher and TUM,BU reached 85% when bagasse was stored in the open air; b) decrease of TCZ (< 1%), making possible reduced damage and maintenance when used in steam boilers; c) without significant degradation as solid fuel with regard to TMV,BS and TCF,BS, provides respectively ignition and stability of fuel, and significant contribution in PCS; d) mean rates for calorific power will be consumed at 15% or more, within the process of bagasse drying; e) available thermal energy (-27 mil TEP) has a significant potential for the co-generation of energy and increase in aggregated value of agro-industrial production. [ABSTRACT FROM AUTHOR]

Aiming at evaluating the effect of the cultural practices soil management and crop rotation on energy conversion and balance, an experiment was conducted in Passo Fundo, Rio Grande do Sul, Brazil, from 2004 to 2009. Four types of soil management were used: 1) no-tillage, 2) minimum tillage, 3) conventional tillage using disk plow, and 4) conventional tillage using moldboard plow and three crop rotation systems: system I - wheat/ soybean; system II - wheat/soybean and common vetch/sorghum; and system III - wheat/soybean, common vetch/sorghum, and white oats/soybean. The experimental design was made with randomized blocks, with split-plots and three replications. The main plot consisted of the soil management systems, while the split-plots consisted of the crop rotation systems. Energy conversion (available energy/consumed energy) and balance (available energy - consumed energy) in a six-year period were discussed in this paper. The sorghum was the crop that showed the highest energy return in comparison to the other crops. The no-tillage system showed higher energy conversion and balance (15.27 and 42,391 Mcal ha-1) than the minimum tillage (12.82 and 35,217 Mcal ha-1) and the conventional tillage systems using disk plow (10.64 and 28.988 Mcal ha-1) and moldboard (10.55 and 28,698 Mcal ha-1). The wheat under crop rotation tended to be more energetically efficient than the monoculture of this cereal. [ABSTRACT FROM AUTHOR]