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All publications of “Paulo Leonel Libardi”

23 results

Soil Water Retention Curve as Affected by Sample Height

Maria Laiane do Nascimento Silva, Paulo Leonel Libardi, Fernando Henrique Setti Gimenes


ABSTRACT: The soil water retention curve is one of the main instruments to assess the soil physical quality and to improve soil management. Traditionally, the equipment most used in the laboratory to determine the retention curve has been Haines funnels and Richards chambers. An important factor to which little attention has been given in the use of these equipaments is the height of the undisturbed soil sample. This work proposes to evaluate the influence of different heights of undisturbed samples […]

Water Balance Components in Covered and Uncovered Soil Growing Irrigated Muskmelon

Paulo Leonel Libardi, Jaedson Cláudio Anunciato Mota, Raimundo Nonato de Assis, Alexsandro dos Santos Brito, Joaquim Amaro


ABSTRACT Knowledge of the terms (or processes) of the soil water balance equation or simply the components of the soil water balance over the cycle of an agricultural crop is essential for soil and water management. Thus, the aim of this study was to analyze these components in a Cambissolo Háplico (Haplocambids) growing muskmelon (Cucumis melo L.) under drip irrigation, with covered and uncovered soil, in the municipality of Baraúna, State of Rio Grande do Norte, Brazil (05º 04’ 48” […]

Diurnal-nocturnal fluctuation of soil water matric potential and soil water total potential gradient

Alexsandro dos Santos Brito, Paulo Leonel Libardi, Jaedson Cláudio Anunciato Mota, Vilson Antonio Klein


As the water matric potential is the most important component of the water total potential in unsaturated soils, it must be measured accurately. The aim of this study was to evaluate the effect of soil temperature on water matric potential and water total potential gradient over the period of water redistribution in a Latossolo Vermelho-Amarelo (Oxisol/Hapludox) located in the municipality of Piracicaba, SP, Brazil. In a circular plot of 3 m diameter, 10 tensiometers with pressure transducers (model SWT3 from […]

Time-space analysis of water balance components in an Oxisol

Neilo Bergamin Moreira, Paulo Leonel Libardi, Monica Martins Silva Salvador, Helon Hébano de Freitas Sousa


Monitoring the variables that constitute the soil water balance equation in a farmed field is important for reliably evaluating water deficit periods during the crop cycle, managing irrigation and estimating nutrient losses through leaching. Components of the water balance equation may vary in space and time, and the study of the temporal stability of the spatial variability of these components is essential for determining the observation points in the field (sites) for monitoring soil moisture accurately with reduced effort in […]

An analysis of soil hydraulic conductivity determination by means of the instantaneous profile method

Adriano Dicesar Martins de Araújo Gonçalves, Paulo Leonel Libardi


The soil hydraulic conductivity K is a property that expresses the ability of the soil in conducting water. It is important for soil management, crops yield and the preservation of soil and environment. The soil hydraulic conductivity can be determined by means of laboratory and field methods, the first better experimentally controlled and the second with less degree of soil disturbing. Among the field methods, the instantaneous profile one is the most used, both the original and the modified in […]

Temporal stability and spatial variability of distribution of soil water storage in a bean-black oat succession

Monica Martins Silva Salvador, Paulo Leonel Libardi, Alexsandro dos Santos Brito, Neilo Bergamin Moreira


Soil water storage is very variable in time and space due to the influence of various environmental factors and topography. The objective was to: i) quantify the soil water storage, ii) assess the temporal stability and spatial variability of a point near to and one distant from the root system in a common bean – black oat succession iii) verify the spatial variability as a function of the soil relief. In the experimental area (1500 m2), in Piracicaba-SP (latitude 22° […]

Distribution of Nitrogen Ammonium Sulfate (15N) soil-plant system in a no-tillage crop succession

Flavia Carvalho da Silva Fernandes, Paulo Leonel Libardi


The N use by maize (Zea mays, L.) is affected by N-fertilizer levels. This study was conducted using a sandy-clay texture soil (Hapludox) to evaluate the efficiency of N use by maize in a crop succession, based on 15N-labeled ammonium sulfate (5.5 atom %) at different rates, and to assess the residual fertilizer effect in two no-tillage succession crops (signalgrass and corn). Two maize crops were evaluated, the first in the growing season 2006, the second in 2007, and brachiaria in […]

Field capacity estimation based on retention curve and soil water flux density

Alexsandro dos Santos Brito, Paulo Leonel Libardi, Jaedson Cláudio Anunciato Mota, Sergio Oliveira Moraes


Field capacity is a parameter of undeniable importance for an adequate irrigation management. From the reliable determination of soil water content and field capacity, crop yields cam be optimized, maximizing the plant water use efficiency and preventing groundwater contamination by leaching of fertilizers and agrochemicals. The objective of this study was to evaluate field capacity (a) from the calculation of soil water flux density during water redistribution in a classical experiment to determine this parameter and (b) from a given […]

Soil physical quality of three soils under mechanical sugarcane harvesting

Karina Maria Vieira Cavalieri, Laércio Alves de Carvalho, Alvaro Pires da Silva, Paulo Leonel Libardi, Cássio Antonio Tormena


The mechanical harvesting of sugarcane (Saccharum officinarum) increases the risks of soil physical degradation. The objective of this study was to determine the least limiting water range (LLWR) and S index to evaluate the physical quality in soils under mechanically harvested sugarcane. Three soils were sampled (layers 0-0.20 and 0.20-0.40 m): clayey Oxisol (clayey LV), loam Oxisol (medium-textured LV) and a sandy Ultisol (sandy PVA). In decreasing order, the LLWR was clayey LV < sandy PVA < medium-textured LV. In […]

Data acquisition system for measurement equipment of soil air permeability

Luciano Roberto da Silveira, Alexsandro dos Santos Brito, Jaedson Cláudio Anunciato Mota, Sergio Oliveira Moraes, Paulo Leonel Libardi


The intrinsic permeability or soil air permeability is an important soil property for the identification of changes in soil porous space caused by soil tillage, in estimations of soil properties that are expensive and difficult to be determined in the laboratory, and for the formulation of flux models in cropped and contaminated soils. The purpose of this study was to develop a data acquisition system (electronic module and software) for intrinsic permeability measurement, in laboratory. High precision of the acquisition […]

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