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Search Results: 1 - 10 of 377 matches for " weighting lysimeter "
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Ajuste do modelo Chistiansen-Hargreaves para estimativa da evapotranspira??o do feij?o no cerrado
Rocha, Omar C.;Guerra, Ant?nio F.;Azevedo, Hamilton M. de;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2003, DOI: 10.1590/S1415-43662003000200013
Abstract: bean producers from the brazilian cerrado region have only one technology for the irrigation management: the measurement of the water tension in the soil through the use of tensiometers. although this methodology has high potential, it has not been widely adopted by the producers. thus, the utilization of models to estimate evapotranspiration estimate has shown to be applicable to the cerrado region. so, this paper aims to evaluate the performance of the chistiansen-hargreaves model to estimate evapotranspiration of black bean crop in the dry season of the brazilian cerrado region. it also aims to provide producers an the adjusted model to estimate evapotranspiration which permit an efficient management for the agricultural irrigated system of the cerrado region. the evapotranspiration of the black bean crop was measured with the use of a weighing lysimeter. the experiment was carried in the brazilian agricultural research corporation (embrapa cerrados), located in planaltina, df, brazil. when calculated with crop coefficient, determined in the research and tested with adjusted energetic term (s0=0.5), the chistiansen-hargreaves model presented an excellent performance and may be used in irrigation management.
Efeitos da cobertura do solo com filme de polietileno azul no consumo de água da cultura da alface cultivada em estufa
Gon?alves, Alexandre O.;Fagnani, Maria A.;Peres, José G.;
Engenharia Agrícola , 2005, DOI: 10.1590/S0100-69162005000300007
Abstract: the covering of the soil is an agricultural practice that intends to control the harmful herbs, to reduce the losses of water by evaporation of the soil, and to facilitate the harvest and the commercialization, once the product is cleaner and healthier. however, when the soil is covered important microclimatic parameters are also altered, and consequently the germination of seeds, the growth of roots, the absorption of water and nutrients, the metabolic activity of the plants and the carbohydrates storage. the current trial intended to evaluate the effect of soil covering with blue colored film on consumptive water-use in a lettuce crop (lactuca sativa, l.). the experiment was carried out in a plastic greenhouse in araras - s?o paulo state, brazil from march 3rd, 2001 to may 5th, 2001. the consumptive water-use was measured through two weighing lysimeter installed inside the greenhouse. crop spacing was 0.25 m x 0.25 m and the color of the film above soil was blue. leaf area index (iaf), was measured six times (7; 14; 21; 28; 35; 40 days after transplant) and the water-use efficiency (eu) was measured at the end. the experimental design was subdivided portions with two treatments, "bare soil" and "covered soil". the average consumptive water-use was 4.17 mm day-1 to the "bare soil" treatment and 3.11 mm day-1 to the "covered soil" treatment. the final leaf area index was 25.23 to the "bare soil" treatment and 24.39 to the "covered soil" treatment, and there was no statistical difference between then.
Combined Effect of Infiltration, Capillary Barrier and Sloping Layered Soil on Flow and Solute Transfer in a Heterogeneous Lysimeter  [PDF]
Le Binh Bien, Dieuseul Predelus, Laurent Lassabatere, Thierry Winiarski, Rafael Angulo-Jaramillo
Open Journal of Modern Hydrology (OJMH) , 2013, DOI: 10.4236/ojmh.2013.33018
Abstract: This aim of this paper is to describe a study of the combined effect of infiltration, capillary barrier and sloping layered soil on both flow and solute transport processes in a large, physical model (1 × 1 × 1.6 m3) called LUGH (Lysimeter for Urban Groundwater Hydrology) and a 3D numerical flow model. Sand and a soil composed of a bimodal sand-gravel mixture were placed in the lysimeter to simulate one of the basic structural and textural elements of the heterogeneity observed in the vadose zone under an infiltration basin of Lyon (France). Water and an inert tracer (KBr) were injected from the top of the lysimeter using a specific water sprinkler system and collected at 15 different outlets at the bottom. The outlet flows and the 15 breakthrough curves obtained presented high heterogeneity, emphasising the establishment of preferential flows resulting from both capillary barrier and soil layer dip effects. Numerical modelling led to better understanding of the mechanisms responsible for these heterogeneous transfers and it was also used to perform a sensitivity analysis of the effects of water velocity (water and solute flux fed by the sprinkler) and the slope interface. The results show that decreasing velocity and increasing the slope of the interface can lead to the development of preferential flows. In addition, the offset of the centre of gravity of the flow distribution at the output increases linearly as a function of the slope angle of the layered soil. This paper provides relevant information on the coupling between hydrodynamic processes and pollutant transfer in unsaturated heterogeneous soil and emphasizes the role of the geometry of the interfaces between materials and boundary conditions as key factors for preferential flow.

Instala??o, calibra??o e funcionamento de um lisímetro de pesagem
Carvalho, Daniel F.;Silva, Leonardo D. B.;Guerra, José G. M.;Cruz, Francisco A.;Souza, Adilson P.;
Engenharia Agrícola , 2007, DOI: 10.1590/S0100-69162007000300005
Abstract: the objective of this work was to construct, install, calibrate and evaluate a weighing lysimeter with load cell, in order to estimate reference evapotranspiration (eto) for the seropédica region - rj. the lysimeter, which has the dimensions of 1.0 m x 1.0 m and 0.7 m in depth, was built with galvanized steel and installed over a metallic structure mounted over transversal bars, in order to concentrate all the assembly mass over a load cell localized in the center of the system. the lysimeter was filled with the same soil layers of the local soil. then a calibration was carried out by means of a linear regression analysis and the whole lysimeter area was planted with bahia grass. the lysimeter system demonstrated to be suitable for estimating eto, yielding a standard error of the linear regression of 0.278 kg or 0.278 mm. in addition, it displayed satisfactorily the variation of the main meteorological elements that influence in eto.
Influência do manejo da irriga??o no meloeiro rendilhado cultivado em ambiente protegido
Silva, Tonny J. A.;Machado, Carmello C.;Bonfim-Silva, Edna M.;Coelho, Rubens D.;
Engenharia Agrícola , 2005, DOI: 10.1590/S0100-69162005000300018
Abstract: aiming to evaluate net-melon fruits under irrigation management, it was carried out an experiment in greenhouse conditions. the experimental area was located at the irrigation farm of the engineering department of - escola superior de agricultura "luiz de queiroz" - esalq/usp in piracicaba, s?o paulo, brazil, planted with bonus 2 cultivar. two irrigation management systems were evaluated by tensiometer and tension lysimeter with two levels of solution fertility (presence and absence). tension lysimeter is a device based on porous cap, capable of supplying water automatically to the plant through a mariotte reservoir (constant hydraulic head). for the treatments with tension lysimeter, the average free water porosity (pla) was 15%. for treatments with tensiometers, the pla was 35% in average, favoring a good relation of air-water throughout the experiment. the temporal variation of the matrix potential in treatments by tensiometer, measured in three depths, presented an average deviation of 9.10% whereas treatments with tension lysimeter were 1.33%. the irrigation management by tensiometers without fertilizer obtained an average weight of the fruits (1,070.4 g) that was almost duplicated in relation to minimum commercial standard (550 g). however, by adding fertilizer in these plants the productivity increment was 4.5 times higher (2,493.8 g). the net-melon fruits presented a low productivity when the free water porosity was lower at 20%.
Evapotranspira??o e coeficientes de cultivo de cafeeiros em fase de forma??o
Flumignan, Danilton Luiz;Faria, Rogério Teixeira de;
Bragantia , 2009, DOI: 10.1590/S0006-87052009000100029
Abstract: quantifying crop water consumption is essential for many applications in agriculture. evapotranspiration (et) of coffee trees, cultivar iapar 59, under sprinkler and drip irrigation and no irrigation, were determined by weighing lysimeters in an experiment conducted in londrina, paraná state, brazil, during two years after crop installation. the crop coefficient (kc) values were determined for the irrigated treatments by the ratio between et and reference evapotranspiration (eto) estimated with the penman-monteith method. the values of et and kc were influenced by irrigation method, rainfall frequency, atmospheric demand and leaf area evolution. the sprinkler irrigated treatment presented the higher mean annual et values (3.1 and 3.4 mm day-1 for the 1st and 2nd year, respectively), followed by drip irrigation (2.9 mm day-1 for the 2nd year) and no irrigation (2.2 and 2.5 mm day-1 for the 1st and 2nd year, respectively). the mean annual kc value was higher under sprinkler (0.99 and 1.03 for the 1st and 2nd year, respectively) and lower for drip irrigation (0.92 for the 2nd year).
Methods to Estimate Lettuce Evapotranspiration in Greenhouse Conditions in the Central Zone of Chile
Casanova P,Manuel; Messing,Ingmar; Joel,Abraham; Ca?ete M,Alberto;
Chilean journal of agricultural research , 2009, DOI: 10.4067/S0718-58392009000100008
Abstract: this study evaluates five methods to estimate crop evapotranspiration in greenhouse conditions. it compares their performance in relation to the evapotranspiration directly determined from water balance measurements (etlys) in an irrigated lettuce (lactuca sativa l.) crop during 9 weeks. daily values of the reference evapotranspiration (eto) from class a pan (cap), piche atmometers (atm), andersson evaporimeters (ane), fao-radiation (fre) and fao-penman-monteith (pme) equations were compared. the methods showed similar temporal variations but at different ranges as follows: ane < cap < fre < pme < atm. furthemore, eto had a clear correlation with solar radiation. crop coefficients (kc = etlys/eto) varied somewhat amongst the methods, but trends were identified for two periods: in the first week, the overall mean kc was 0.3 (± 0.1) and in weeks 2 to 9 on average 0.6 (± 0.3). the greenhouse values of kc were lower than those generally adopted for lettuce in field conditions. in terms of irrigation design, crop evapotranspiration can be estimated by the methods in this study, on the condition that the appropriate crop coefficients are applied. the fact that ane showed values closest to those of etlys, along with cost and management convenience, makes it an advantageous alternative as compared to the other methods.
Lixivia??o do inseticida thiamethoxam em macrolisímetros de duas classes de solo
Castro, Nélio Ricardo Amaral;Rigitano, Renê Luís de Oliveira;Lima, José Maria de;Guerreiro, Mário César;
Ciência e Agrotecnologia , 2008, DOI: 10.1590/S1413-70542008000600021
Abstract: the leaching of thiamethoxam in two brazilian soils, a typic acriferric red latosol (lvwf) and a typic dystrophic red-yellow argisol (pvad), was investigated in macrolysimeters (1.0 m diameter and depth of 0.45, 0.90 and 1.80 m) of undisturbed material of the soils, which were kept without vegetation and under field conditions. the insecticide was applied at the beginning of the rainy season, using the formulation actara 250 w?, which was diluted in 100 ml of water and applied on the lysimeters surface. the water percolated through the lysimeters was collected until the end of rainy season of the following year, with samples being taken for determination of thiamethoxam concentration, performed by hplc. the results showed a high mobility of thiamethoxam in both soils, with more intense leaching of the compound in the pvad than in the lvwf. the total amounts of thiamethoxam leached below 0.45 m were equivalent to 53.8 and 19.4% of the applied amount, respectively for the pvad and lvwf. thiamethoxam residues were also found in the water collected from the 0.90 and 1.80 m lysimeters of both soils. these results indicate a high potential of thiamethoxam leaching under practical conditions of its use in the studied soils, despite the lack of vegetation.
Lixivia??o do fungicida triadimenol em macrolisímetros de latossolos da regi?o de Lavras-MG
Bastos, Cristiane Jorge;Rigitano, Renê Luís de Oliveira;Lima, José Maria de;Castro, Nélio Ricardo Amaral;
Ciência e Agrotecnologia , 2005, DOI: 10.1590/S1413-70542005000400008
Abstract: the leaching of the fungicide triadimenol was investigated in macrolysimeters containing undisturbed soil material of a distroferric red latosol and of a distrofic yellow red latosol, under field conditions. a granular formulation of the pesticide was applied at the recommended rate, at 5-cm depth, in soil columns of 1.0 m diameter and 0.45 and 0.90 m long, at the beginning of the rainy season. the volume of percolated water in each lysimeter was measured during the following five months, with samples of this water being periodically taken for analysis of residues of the chemical. the pesticide residues were extracted through partitioning with dichloromethane, and subsequently measured by gas-liquid chromatography, with electron capture detector. the mobility of triadimenol was shown to be very low, and was attributed to its high sorption to the organic matter of the soils. this sorption accounted for the leaching of less than 0.3% of the applied dose, below 0.90 m. triadimenol was still found in the leaching water at the end of the experiment, and an appreciable portion of the applied dose was estimated to remain in the lysimeters by the end of the rainy season. the leaching of the chemical did not differ markedly between the soils.
água salina nos atributos químicos do solo e no estado nutricional da mandioqueira
Holanda Filho, Roberto S. F. de;Santos, Delfran B. dos;Azevedo, Carlos A. V. de;Coelho, Eugênio F.;Lima, Vera L. A. de;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2011, DOI: 10.1590/S1415-43662011000100009
Abstract: the purpose of this study was to assess the influence of saline water on chemical properties of the soil and nutritional attributes of cassava. the work was conducted in the area of irrigation and drainage of if baiano, campus de senhor do bonfim, ba (10° 28’s, 40° 11’w and 550 m). the experimental design was completely randomized, consisting of seven treatments and three replicates. the treatments consisted of control (rainfed), a treatment irrigated with drinking water (100% of etc) and five treatments irrigated with saline water of 3 ds m-1 with varying water depths: 110, 120, 130, 140 and 150% of etc. the use of saline water increased the exchangeable sodium percentage, the sodium adsortion ratio and the electrical conductivity of the soil in both 0-0.20 and 0.20-0.40 m dephts. regarding the leaf nutritional status of cassava, the treatments influenced only the contents of calcium, magnesium and chlorine.
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