Perda por evaporação na pulverização em função das condições psicrométricas do ar

• Autor(a) principal: Maciel, Christiam Felipe Silva
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3643
• topic: Pulverização; Evaporação; Agrotóxicos; Spray; Evaporation; Pesticides; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::MECANIZACAO AGRICOLA

Pesticides loss by evaporation causes inefficiency of spraying, besides causing environmental impacts and intoxications. Thus, to ensure a safe pesticides application, with maximum efficiency and minimum environmental impact, the aim of this work was to characterize the hydraulic spray nozzles, determine the droplet spectrum depending on air psychrometric conditions, and to estimate and to model pesticides evaporation depending on air psychrometric conditions. During the nozzle characterization two models of nozzle were used to obtain the pattern and uniformity of distribution, as well as the droplet spectrum. The symmetry of distribution was also obtained from the data of pattern of distribution. The determination of droplet spectrum, and the estimation and modeling of pesticides evaporation depending on air psychrometric conditions were carried out inside of a climatic chamber to obtain twenty air vapor pressure deficit (VPDair) levels. The determination of droplet spectrum was performed by the laser particle analyzer model Spraytech. The nozzles LD 11002 and MAG-2 did not have good uniformity of distribution for the boom height specified by the manufacturer. The nozzle LD 11002 showed asymmetry and this was influenced by working pressure. The droplets diameter produced by the nozzles LD 11002 and MAG-2 reduced with increasing the working pressure. Increasing VPDair, increased the VMD, the Dv90, the SPAN and the percentage of sprayed volume comprised by droplets larger than 600 μm, on the other hand reduced the percentage of sprayed volume comprised by droplets with diameter between 100 and 200 μm, between 200 and 300 μm, between 300 and 400 μm, between 400 and 500 μm and between 500 and 600 μm. Even obeying the recommended climatic conditions for pesticides application, there is loss of sprayed volume by evaporation. For the spray nozzle LD 11002 and working pressure of 300 kPa, the pesticides loss by evaporation can reach approximately 27 % under weather conditions characterized by low wind velocity, high air temperature and low relative humidity.