Filho D.O.,Federal University of Viçosa |
Teixeira C.A.,Federal Rural University of Pernambuco |
De Silva J.S.E.,Federal University of Viçosa |
Reis H.O.,Federal University of Viçosa |
Engenharia Agricola | Year: 2010
The importance of renewable natural resources in the world is growing. In the production process of charcoal it is possible to increase the overall efficiency of transformation of eucalyptus wood in charcoal. In industrial process cooling time of the charcoal mass varies from 6 to 8 days, using the natural cooling of the charcoal mass, and the temperature for the opening of the mud ovens is about 60 °C and the initial temperature of the charcoal mass is around 480 °C. Thus, it was studied a system of cooling oven carbonization using injection of steam, with the goal of reducing the cooling time of the charcoal. It was built an oven type container in a test scale with the following dimensions 3.0 × a 2.0 × 1.6 m, as well as a system burner for exhaustion gases from the wood carbonization, instrumented thermocouples type K and a data acquisition system at the Laboratories of the Energy Area and Pre Processing of Agricultural Products of the Agricultural Engineering Department of Federal University of Viçosa, Viçosa, Minas Gerais, Brazil. It was built an oven container type on a laboratory scale of dimensions equal to 3.0 x 2.0 x 1.6 m and a firing system of gas exhaustion from the carbonization of wood, instrumented with temperature sensors type k, connected to a data system acquisition. It was also used a boiler to generate steam for the fast cooling of the oven. The cooling time of the coal mass was reduced to about two days by the injection of water vapor when compared to the natural cooling process.
Water-retention curve modelled by the psychrometer method for soil physical quality index determination [Curva de retenção de água elaborada pelo método do psicrômetro para uso na determinação do índice "S" de qualidade física do solo]
do Sacramento J.A.A.S.,Institute Biodiversidade e Florestas |
Engenharia Agricola | Year: 2015
Soil-water retention curve (SWRC) represents the relation between the water content in soil and the suction energy that retains it within porous media and/ or adsorbed in mineral particles of soil. This curse is also used to calculate indices of soil physical quality, "S", as proposed in 2004 by Dexter. Such index can be obtained by several methods; among them, the pressure plate apparatus (Richards's pressure chamber) is the primary and most common one. Electronic equipment like a WP4 psychrometer have been suggested as usefulness tools to establish SWRCs. In this context, we aimed to evaluate the potential of SWRCs, developed by a psychrometer, in determining the soil physical quality index. The results show that SWRCs prepared by the psychrometer method had alterations in the setting parameters related to the equation of van Genuchten. Therefore, the generated curves may underestimate the values of the "S" index calculated.
Neto P.H.W.,State University of Ponta Grossa |
Justino A.,State University of Ponta Grossa |
Frare I.,Gerente tecnico da Fazenda Mutuca |
Gomes J.N.,Agronomo |
Garcia L.C.,State University of Ponta Grossa
Engenharia Agricola | Year: 2013
The aim of this study was to determine whether the form of placing the fertilizer by the planter during the sowing under mulch in the no till system affects the yield of corn. The treatments consisted of placing the fertilizer during the seeding 0.05 m below and beside the seed, in front of the cutting blade and without fertilizer, in 03 farms during 03 cropping years. The experimental design at each farm was the randomized block, with 08 repetitions, whose plots had 30 m2 each. The initial population and yield components were evaluated. Under the experimental conditions it is concluded that base fertilization can affect the yield. Fertilizer placement can affect the initial stand, but not the yield.
Cortez J.W.,Agronomo |
Lopes H.L.,Federal University of Vale do São Francisco |
Coelho D.S.,University of Pernambuco |
Arcoverde S.N.S.,Federal University of Vale do São Francisco
Engenharia Agricola | Year: 2014
Since the advent of mechanized farming and intensive use of agricultural machinery and implements on the properties, the soil began to receive greater load of machinery traffic, which can cause increased soil compaction. The aim of this study was to evaluate the spatial variability of soil mechanical resistance to penetration (RP) in the layers of 0.00-0.10, 0.10-0.20, 0.20-0.30 and 0.30-0.40m, using geostatistics in an area cultivated with mango in Haplic Vertisol of the northeastern semi-arid, with mobile unit equipped with electronic penetrometer. The RP data was collected in 56 points from an area of 3 ha, and random soil samples were collected to determine the soil moisture and texture. For RP data analysis we used descriptive statistics and geostatistics. The soil mechanical resistance to penetration presented increased variability, with adjustment of the spherical and exponential semivariograms in the layers. We found that 42% of the area in the layer of 0.10-0.20m showed RP values above 2.70 MPa. Maximum values of RP were found in the layer of 0.19-0.27m, predominantly in 56% of the area.
Carvalho G.C.,Federal Rural University of Pernambuco |
Coelho E.F.,Agricola |
Da Silva A.D.S.A.M.,Agronomo |
Engenharia Agricola | Year: 2014
The objective of this study was to evaluate growth and yield of papaya cv. Sunrise solo under trickle irrigation system configurations. A random block design was used with six treatments and four replications. Treatments were: T1-a 32 L h-1 micro sprinkler; T2 - a 43 L h-1 micro sprinkler and T3 - a 60 L h-1 micro sprinkler for four plants; T4 - Drip system with four emitters per plant on one lateral line per crop row; T5 - Drip system with eight emitters per plant on two laterals line per crop row; T6 - Drip system with four emitters per plant on one lateral line distributed as pig tail. The dripper flow rate was 4 L h-1and they were apart each other 0.50 m. Crop growth variables were measured every two weeks. Production variables were evaluated during harvest. The treatment that presented superiority was irrigated by micro sprinkler system with flow rate of 43 L h-1.