Siqueira V.C.,Federal University of Lavras |
Resende O.,IF Goiano Campus Rio Verde |
Chaves T.H.,IF Goiano Campus Rio Verde
Revista Ceres | Year: 2012
Given the necessity of developing jatropha cultivation equipment, this work adjusted different mathematical models to experimental data obtained from the drying of jatropha seeds submitted to different drying conditions and selected the best model to describe the drying process. The experiment was carried out at the Federal Institute of Goiás - Rio Verde Campus. Seeds with initial moisture content of approximately 0.50 (kg water/kg dry matter) were dried in a forced air-ventilated oven, at temperatures of 45, 60, 75, 90 and 105oC to moisture content of 0.10 ± 0.005 (kg water/kg dry matter). The experimental data were adjusted to 11 mathematical models to represent the drying process of agricultural products. The models were compared using the coefficient of determination, chi-square test, relative mean error, estimated mean error and residual distribution. It was found that the increase in the air temperature caused a reduction in the drying time of seeds. The models Midilli and Two Terms were suitable to represent the drying process of Jatropha seeds and between them the use of the Midili model is recommended due to its greater simplicity.
Ribeiro P.H.P.,State University of Goias |
Teixeira M.B.,IF Goiano Campus Rio Verde |
Coelho R.D.,University of Sao Paulo |
Neto J.D.,Federal University of Campina Grande
IRRIGA | Year: 2014
When properly used, the practice of irrigation becomes an effective tool in raising the income of producers, generating jobs and increasing the supply of agricultural products. Among the irrigation methods, drip irrigation has been the most used in areas of water scarcity. Several factors may compromise the uniformity of water distribution in drip irrigation, such as non-uniformity due to manufacturing processes, improper planning of the system, as well as clogging of emitters. In this context, a study was conducted to characterize the hydraulic performance of drip emitter pipes used in subsurface dripping as well as to evaluate the susceptibility of the NAAN PC emitter pipe to hysteresis. The experiment was conducted in the experimental area of Goiás Federal Institute – Urutaí Campus. A motor-pump assembly, a filter system and three lateral rows, 3 meters long were used. A total of ten subsurface emitters in each row were evaluated for 10 minutes each one, and under pressures of 50, 100, 150, 200 and 250 kPa. The following parameters were evaluated: mean discharge, coefficient of discharge variation and uniformity of water distribution. The study model was sensitive to hysteresis for pressure values higher than 200 kPa. © 2014 Universidade Estadual Paulista - UNESP. All rights reserved.
Rodrigues-Cabral J.S.,IF Goiano Campus Rio Verde |
Guimaraes-Silva F.,IF Goiano Campus Rio Verde |
Luiz-Souchie E.,IF Goiano Campus Rio Verde |
Carbone-Carneiro M.A.,Federal University of Lavras
Agrociencia | Year: 2012
Soil microbiota carries out important functions in ecosystems, since it influences growth, mineral nutrition and plant health. Phosphorus (P) is the most limiting nutrient in tropical soils and P-solubilizing microorganisms (PSMs) and the arbuscular mycorrhizal fungi (AMF) are the most important groups of the soil microbial community. The aim of this study was to evaluate the effect of inoculating PSMs and AMF on the development of cashew trees (Anacardium othonianum Rizzini) from the Brazilian Cerrado growing on different substrates. An experiment was carried out in a greenhouse and the experimental design was completely randomized with a factorial 4 × 2 arrangement of treatments: PSMs, AMF, PSMs + AMF and the control. In addition, two substrates were used: a pure one with a sandy loam texture and a mixture of clay loam and clayish textures. Twelve replicates were performed. Data were subjected to an analysis of variance, and means were compared with the Tukey test (p≤0.05). The co-inoculation with PSMs and AMF resulted in greater height and shoot dry matter of seedlings compared to isolated inoculations with these organisms. Seedlings increased height and shoot fresh and dry matter when grown in a mixture of substrates (soil with clay loam and clay textures). The use of a mixture of substrates also resulted in a greater symbiotic efficiency of Glomus etunicatum.
Goncalves D.N.,IF Goiano Campus Rio Verde |
Resende O.,IF Goiano Campus Rio Verde |
Costa L.M.,IF Goiano Campus Rio Verde |
Prado M.C.,IF Goiano Campus Rio Verde
Engenharia Agricola | Year: 2014
The Knowledge of the physical properties of agricultural products has great importance for the construction and operation of equipment for drying and storage, to achieve increased efficiency in post-harvest operations. The aim was to determine and analyze the physical properties of crambe fruits during drying at different temperatures. Crambe fruits with an initial moisture content of 0.36 (decimal d.b.) which was reduced by drying at 37.0; 58.8 and 83.5 °C and relative humidity of 29.4; 11.2 and 3.2%, respectively, to 0.09 ± 1 (decimal d.b.). At different levels of moisture contents (0.36; 0.31; 0.26; 0.21; 0.17; 0.13 and 0.09 decimal d.b.), was evaluated the intergranular porosity, the bulk density, the true density as well as the volumetric shrinkage and the fruit mass. The study was installed by the factorial 3 × 7, and three drying temperatures and seven moisture contents in a randomized design. Data were analyzed using regression. The bulk density and the true density decreases along the drying process; the volumetric shrinkage and the mass increased with lower moisture content and the intergranular porosity decreased sharply with the increasing drying temperature.