Granulometry is an initial factor to be considered in soil research as it plays a fundamental role in physical and chemical properties. The objective of this study was to characterize the granulometric fractions of soil, obtained using the screening and sedimentation method. The Dynamic Light Scattering (DLS), Mid-Infrared (MIR), and Scanning Electron Microscopy with Field Emission Gun (SEM-FEG) techniques were used for this purpose. The quantitative results showed that this soil presents high percentage of clay, followed by fine sand fraction, silt fraction and, finally, the coarse sand fraction. The results obtained by DLS qualify this technique as a procedure to evaluate the quality of the granulometric fractionation of the clay fraction. The MIR analyzes detected characteristic vibrational states of minerals such as kaolinite, halloysite, gibbsite, and quartz. Few works in the literature characterize the clay fraction of the soil without chemical treatment using the SEM-FEG technique. Thus, in this work, pseudo-hexagonal structures were identified, typical of the kaolinite mineral and, to a lesser extent, structures with a filamentous needle-like morphology, which can be ascribed to illite and/or halloysite, whose inorganic functional groups were identified by MIR in the clay fraction of the soil.

ABSTRACT Use of soil in forensic science is related to its several chemical, physical, and biological properties associated with its capacity to adhere to different materials and surfaces. Forensic soil experts and police investigators have been using soil samples as an aid in criminal investigations. Soils can act as fingerprints because they present contrasting physical, chemical, biological, and mineralogical properties. However, depending on the analytical tools utilized to characterize the soil, differentiating the samples when they have similar properties might be impossible. Thus, soil utilization as a fingerprint material requires increasing the number of variables measured as well as the accuracy and precision of the measurements. This study presents the feasibility of methods based on X-ray fluorescence (XRF) and radiation interaction parameters to discriminate soils for forensic investigations. Analyses of soil particle size, elemental composition (XRF), mass attenuation coefficient (μ), atomic (σa) and electronic (σe) cross-sections, effective atomic number (Zeff), and electron density (Nel) were carried out to evaluate the potential of nuclear parameters to differentiate soils. Ten different soil types collected at 0.00-0.05 m layer were studied. The radiation interaction parameters were obtained through the XCOM computer code, while the experimental measurements were carried out by the traditional gamma-ray attenuation method utilizing the radioactive sources of 241Am and 137Cs. The results showed that the soils presented broad differences in terms of clay, silt, and sand contents as well as in the major oxides. These differences influenced the radiation attenuation properties as verified through the multivariate analysis. For the lowest photon energy studied (10 and 30 keV), σe was the most interesting parameter to discriminate the soils. For energies above 59.5 keV, Zeff and Nel were the most important parameters. Good agreement was found between the calculated and measured parameters. The findings of this study indicate that radiation interaction parameters have great potential for crime scene investigation providing new parameters for better discrimination of soils. The main advantage of the method presented here is that it is fast, easy to implement, does not require powerful computers, and the XCOM code can be run online at the NIST (National Institute of Standards and Technology, USA) website.

Abstract The purpose of this research was to discriminate soil fractions using mineralogical and elemental analyses and to show those fractions that present greater contribution to the soil mass attenuation coefficient (μ) as well as their partial cross-sections for photoelectric absorption (PA), coherent scattering (CS) and incoherent scattering (IS). Soil samples from different places of Brazil classified as Yellow Argisol, Yellow Latosol and Gray Argisol were submitted to elemental and mineralogical analyses through energy dispersive X-ray fluorescence (EDXRF) and Rietveld Method with X-ray diffraction data (RM-XRD). The mixture rule was utilized to calculate μ of each soil. The EDXRF analysis showed as predominant elements Si, Al, Fe and Ti oxides. The highest contents were Si (914.3 to 981.3 g kg-1) in the sand fractions, Al (507.9 to 543.7 g kg-1) and Fe (32.5 to 76.7 g kg-1) in the clay fractions, and Ti (18.0 to 59.0 g kg-1) in the silt fractions. The RM-XRD allowed identifying that the sand fractions are predominantly made of quartz (913.3 to 995.0 g kg-1), while the clay greatest portion is made of kaolinite (465.0 to 660.6 g kg-1) and halloysite (169.0 to 385.0 g kg-1). The main effect responsible for μ was IS (50 to 61.4%) followed by PA (28 to 40.1%) and CS (9.9 to 10.6%). By using the principal component analysis (PC-1: 57.5% and PC-2: 20.9%), the samples were differentiated through the discrimination between physical, chemical and mineralogical properties. The results obtained suggest that general information about the radiation interaction in soils can be obtained through the elemental and mineralogical analyses of their fractions.

ABSTRACT This review presents the basic research and some applications of the gamma-ray attenuation, neutron gauges, and 137Cs fallout techniques for studying soil physical processes and properties. The selected studies aimed to give the readers a general idea of the use of these nuclear techniques carried out by Brazilian researchers in the past decades. It is expected to assist future researchers by identifying knowledge gaps and opportunities for applying the methods presented here. Around 100 studies were selected for this review. The papers dealing with gamma-ray attenuation are mostly related to the analysis of soil radiation interactions, the measurement of basic soil physical properties, the evaluation of hydraulic conductivity, water retention curve, and soil mechanical analysis. Neutron gauge applications are related to monitoring the water distribution and balance at the field scale, procedures for calibrating the existing gauge for the Brazilian soils, and analyzing the spatial and temporal variability of the soil water content. The 137Cs methodology involves studies about the erosion and sediment deposition in small watersheds and riparian zones, the spatial variability of 137Cs inventories at reference sites, and the measurement of sediment spatial distributions. Future studies with the gamma-ray attenuation methodology should focus on a better comprehension of the photon interaction with the soil and a correct selection of photon energies to investigate contrasting soils. This is mandatory for adopting it as a reliable tool for soil characterization. This review also revealed that the challenges for the future use of the 137Cs fallout technique involve the continuous decrease of the 137Cs activity worldwide, including in Brazil. Advances in detection systems (gamma spectrometers) will be required to overcome this issue. Future studies should focus on the use of correction factors related to the enrichment of fine particles during the transport of sediments to improve the estimates obtained through the conversion models. The use of neutron gauges to detect soil water content at the field scale depends on the adoption of reliable calibration curves. Then, comprehending how soil properties alter this curve and how it affects the water balance is a study of great interest. Motivated by strict regulations on the use of radioactive materials, the adoption of gauges with less activity is becoming a new goal. Thus, the development of more effective systems of neutron detection is crucial.

Abstract This paper presents the description of methods for using in the analysis of the pore size distribution of complex porous media as, for instance, soils. The sequence of analyses presented here can be implemented in classes of post-graduation in physics applied to earth, soil, and environmental sciences. The objective was to present the use, by students and/or researchers, of free access software to analyze images for obtaining some morphological aspects of porous systems. Two methods of obtaining the pore size distribution are presented: the first one is based on ImageJ internal routines, and the second in the study presented in Yang [1]. The results obtained permitted a detailed analysis of three-dimensional(3D) images of porous systems and also obtaining the pore size distribution of the investigated medium. The procedures here introduced can easily be extended for educational purposes in courses related to the investigation of systems with complex internal structures.

Abstract The sandstones of the Furnas Formation in the State of Paraná, south of Brazil, are located in regions with great importance due to the natural heritage found in the rocky forms and associated flora and fauna. This paper presents a detailed analysis of the internal structure of diverse sandstones of the Furnas Formation. X-ray microtomography allowed 3D characterization of the number, pore size and shape distributions of the sandstones. Images with voxel size of 603 µm3 were utilized to evaluate the sandstone’s macroporosity. The main results obtained indicate that higher macroporosities were observed in coarser and some types of silicified sandstones. In general, fine sandstones were characterized by the largest number of pores. As a general conclusion the size and shape distribution of pores seem to have a variable relation with genetic factors as grain size and cement (siliceous and/or ferruginous).

ABSTRACT Liming represents a management procedure that can affect the soil structure and its thermodynamic processes. In this context, the aims of this study were to assess (i) the effects of the surface and incorporated liming on the clay dispersion, soil water availability, and aeration capacity; (ii) the influence of soil chemical alterations in its physical attributes. For this, a field experiment was installed in a family farming property, located in the southeastern region of the State of Paraná, in a Dystrudept soil. The treatments were 3 application modes (on the surface, incorporated via plowing and incorporated via subsoiling and harrowing), with and without 15 Mg∙ha–1 of lime, aiming to increase the base saturation in the topsoil (0 – 0.20 m) to approximately 70%. Eighteen months after application, undisturbed and disturbed soil samples were collected from the 0 – 0.10 and 0.10 – 0.20 m layers to evaluate the waterdispersed clay (WDC), water content at the field capacity (θFC) and at the permanent wilting point (θPWP), plant available water capacity (PAWC), relative water capacity (RWC), aeration capacity (AC), granulometry and the soil structural and chemical attributes. WDC content in the 0 – 0.10 m layer increased when the soil was revolved and it was influenced exclusively when lime was applied on the soil surface. With surface liming there were increase in θFC, θPWP, PAWC and RWC, and reduction in AC in the 0 – 0.10 m layer. In the 0.10 – 0.20 m layer isolated effects were verified of the modes application and liming on θFC, PAWC and RWC, while θPWP was not influenced by treatments. The soil water availability and aeration capacity alterations were mainly affected by micro and macroporosity increases, pH reduction, Al3+ precipitation, and substitution of this ion in the exchange complex by Ca2+ and Mg2+.

RESUMO. O manejo de plantas invasoras exerce papel chave na minimização dos processos de degradação de atributos físicos do solo tais como compactação e erosão hídrica. Diferentes manejos de plantas invasoras podem induzir mudanças distintas na estrutura do solo. Um atributo físico do solo importante na análise de modificações de sua estrutura é a curva de retenção (CRA). O objetivo desse trabalho foi verificar o uso de atributos físico-hídricos para compreender o efeito dos manejos de plantas invasoras na estrutura do solo. Duas camadas (0-0,05 e 0,10-0,15 m) e seis manejos, subdivididos em dois grupos, localizados nas entrelinhas de lavoura cafeeira foram analisados: I. sem distúrbio do solo e cobertura (sem capina, herbicida de pós-emergência, roçadora mecânica); II. distúrbio do solo e sem cobertura (capina manual, enxada rotativa, herbicida de pré-emergência). O solo coletado em mata nativa foi considerado referência. Os resultados mostraram que a função capacidade de água, obtida pela CRA, pode ser uma ferramenta interessante para avaliar o efeito dos métodos de manejo de plantas invasoras na estrutura do solo. Avaliações da porosidade livre de água nos diferentes potenciais mátricos também apresentaram resultados interessantes. Resultados distintos dos manejos de plantas invasoras foram obtidos nas profundidades analisadas em relação à floresta.

ABSTRACT. Weed management plays a key role in the minimization of soil physical degradation processes such as compaction and hydric erosion. Different weed control managements can induce distinct changes in soil structure. One important soil physical attribute used for the analysis of modifications in soil structure is the soil water retention curve (SWRC). The objective of this work was to verify the use of physico-hydrical attributes to understand the effect of weed control managements on soil structure. Two soil layers (0-0.05 and 0.10-0.15 m) and six weed control managements divided into two groups were analyzed: I. no soil disturbance and ground cover (no weed control, post-emergence herbicide, mechanical mower); and II. soil disturbance and no ground cover (hand-hoe weeding, rotary tiller, pre-emergence herbicide). An area of native forest was used as reference. The results showed that the volumetric water capacity derived from the SWRC can be an interesting tool to evaluate the impact of weed control managements on soil structure. Evaluations of the air-filled porosity variation for different pressure heads also presented interesting findings. Distinct results of the weed control managements were found for the different depths analyzed in relation to the forest.

RESUMO Densidade de partículas, umidades gravimétrica e volumétrica e porosidade são conceitos básicos importantes para caracterizar sistemas porosos, como é o caso do solo. Neste estudo, apresentou-se uma proposta de método experimental para a medida dessas grandezas físicas, em aulas de física experimental, em amostras de meios porosos compostos de esferas de diâmetros iguais (meio monodisperso) e diâmetros diferentes (meio polidisperso). A não utilização de amostras de solo é em razão da dificuldade de trabalhar com amostras desse meio poroso em laboratórios dedicados ao ensino de física experimental básica. O artigo apresenta o método a ser seguido e os resultados para dois estudos de caso, um meio monodisperso e outro polidisperso. Os resultados de densidade de partículas apresentados foram bastante próximos dos valores teóricos para as esferas de chumbo, cujo desvio relativo (DR) foi de -2,9 %, e para as esferas de ferro, de +0,1 %. A porosidade também evidenciou baixos DR, -3,6 %, para esferas de chumbo, e -1,2 %, para esferas de ferro, na comparação dos procedimentos, utilizando as densidades de partículas e do meio poroso e a umidade volumétrica de saturação, e dos meios monodisperso e polidisperso.

ABSTRACT Particle density, gravimetric and volumetric water contents and porosity are important basic concepts to characterize porous systems such as soils. This paper presents a proposal of an experimental method to measure these physical properties, applicable in experimental physics classes, in porous media samples consisting of spheres with the same diameter (monodisperse medium) and with different diameters (polydisperse medium). Soil samples are not used given the difficulty of working with this porous medium in laboratories dedicated to teaching basic experimental physics. The paper describes the method to be followed and results of two case studies, one in monodisperse medium and the other in polydisperse medium. The particle density results were very close to theoretical values for lead spheres, whose relative deviation (RD) was -2.9 % and +0.1 % RD for the iron spheres. The RD of porosity was also low: -3.6 % for lead spheres and -1.2 % for iron spheres, in the comparison of procedures – using particle and porous medium densities and saturated volumetric water content – and monodisperse and polydisperse media.

Compreender como mudanças nas práticas de manejo do solo influenciam a dinâmica da estrutura dele, a partir da quantificação da sua qualidade física e da distribuição do tamanho de poros, pode em muito melhorar a previsão do comportamento físico do solo e do rendimento das culturas agrícolas. Os objetivos deste estudo foram determinar índices para quantificar a qualidade física do solo, em dois sistemas de manejo distintos (pousio e aração); e analisar o impacto desses dois sistemas na distribuição do tamanho de poros, obtido a partir de dados de retenção de água no solo. As curvas de retenção foram medidas utilizando câmaras de Richards, e os dados experimentais foram ajustados pelo modelo de van Genuchten (m = 1-1/n). Embora os valores de densidade do solo encontrados sejam altos, o solo em sistema de aração apresentou bons índices de qualidade física, com manutenção da capacidade para permitir bom desenvolvimento radicular. No entanto, o solo em sistema de pousio apresentou uma estrutura pior com restrições de água disponível em relação ao sistema de aração. Esses dois sistemas de manejo apresentaram distintas distribuições de tamanhos de poros. Os resultados evidenciaram que o solo em sistema pousio sem restrição de tráfego, comum nesse tipo de prática, apresentou resultados piores em relação aos obtidos pelo sistema de aração em termos de estrutura e qualidade física.

Quantification of soil physical quality (SPQ) and pore size distribution (PSD) can assist understanding of how changes in land management practices influence dynamics of soil structure, and this understanding could greatly improve the predictability of soil physical behavior and crop yield. The objectives of this study were to measure the SPQ index under two different land management practices (the continuous arable cropping system and natural bush fallow system), and contrast the effects of these practices on the structure of PSD using soil water retention data. Soil water retention curves obtained from a pressure chamber were fitted to van Genuchten’s equation, setting m (= 1-1/n). Although values for soil bulk density were high, soils under the continuous arable cropping system had good SPQ, and maintained the capacity to support root development. However, soils under the natural bush fallow system had a worse structure than the continuous arable system, with restrictions in available water capacity. These two management systems had different PSDs. Results showed the inferiority of the natural bush fallow system with no traffic restriction (which is the common practice) in relation to the continuous arable cropping system in regard to physical quality and structure.

A análise do sistema poroso do solo representa um importante passo para caracterizar a sua estrutura. Propriedades como formato e número de poros podem ser determinadas a partir de medidas do sistema poroso do solo. Este estudo apresentou uma caracterização em três dimensões (3D) do formato e número de poros de um solo subtropical. Um microtomógrafo de raios-X de segunda geração equipado com detector do tipo plano foi utilizado neste trabalho. A voltagem e corrente de operação foram, respectivamente, 120 kV e 80 mA. As amostras de solo analisadas foram coletadas em três diferentes profundidades (0-10, 10-20 e 20-30 cm). Os resultados possibilitaram análises qualitativas (imagens) e quantitativas em 3D da estrutura do solo, revelando o potencial da técnica microtomográfica e também o estudo de diferenças na macroporosidade do solo em diferentes profundidades. A macroporosidade foi de 5,14 %, na camada de 0-10 cm; 5,10 %, em 10-20 cm; e 6,64 %, em 20-30 cm. A macroporosidade dos poros não classificados (NC) foi de 0,30 % (0-10 e 10-20 cm) e 0,40 % (20-30 cm), ao passo que os poros do tipo equante (EQ) apresentaram valores de 0,01 % para todas as profundidades analisadas.

Analysis of the soil pore system represents an important way of characterizing soil structure. Properties such as the shape and number of pores can be determined through soil pore evaluations. This study presents a three-dimensional (3D) characterization of the shape and number of pores of a sub-tropical soil. To do so, a second generation X-ray microtomograph equipped with a plain type detector was employed. A voltage of 120 kV and current of 80 mA was applied to the X-ray tube. The soil samples analyzed were collected at three different depths (0-10, 10-20, and 20-30 cm). The results obtained allowed qualitative (images) and quantitative (3D) analyses of the soil structure, revealing the potential of the microtomographic technique, as well as the study of differences in soil macroporosity at different depths. Macroporosity was 5.14 % in the 0-10 cm layer, 5.10 % in the 10-20 cm layer, and 6.64 % in the 20-30 cm layer. The macroporosity of unclassified pores (UN) was 0.30 % (0-10 and 10-20 cm) and 0.40 % (20-30 cm), while equant pores (EQ) had values of 0.01 % at the three depths under analysis.

Na ciência do solo, um método direto que permite o estudo da distribuição dos poros do solo é aquele baseado na análise de imagens digitais em duas dimensões (2D). Tal técnica fornece resultados quantitativos do formato, número e tamanho de poros do solo. O uso de programas específicos para o tratamento e processamento de imagens possibilita um método rápido e eficiente para quantificar o sistema poroso do solo. No entanto, pelo alto custo dos programas comerciais, os programas livres podem ser uma interessante alternativa para análises da estrutura do solo. Objetivou-se, nesse trabalho, avaliar a qualidade dos dados fornecidos pelo programa livre "Image J", usado para caracterizar o espaço poroso de dois latossolos (Latossolo Vermelho-Amarelo e Latossolo Vermelho) da região sudeste do Brasil. A técnica de análise de distribuição de poros, a partir de blocos impregnados com resina foi utilizada nesse trabalho. As imagens 2D obtidas usando uma câmera CCD acoplada a um microscópio óptico convencional. Após a aquisição e tratamento das imagens, as mesmas foram processadas e analisadas, usando os programas "Noesis Visilog 5.4®" (selecionado como programa padrão) e "ImageJ". Os parâmetros escolhidos para caracterizar o espaço poroso foram: formato, número e distribuição de tamanho de poros. Para ambos os solos, os resultados obtidos para a porosidade total pela imagem (%), número total de poros e distribuição de tamanho de poros mostraram que o programa "ImageJ" pode ser utilizado na caracterização do espaço poroso de amostras impregnadas com resina.

In the soil science, a direct method that allows the study of soil pore distribution is the bi-dimensional (2D) digital image analysis. Such technique provides quantitative results of soil pore shape, number and size. The use of specific softwares for the treatment and processing of images allows a fast and efficient method to quantify the soil porous system. However, due to the high cost of commercial softwares, public ones can be an interesting alternative for soil structure analysis. The objective of this work was to evaluate the quality of data provided by the Image J software (public domain) used to characterize the voids of two soils, characterized as Geric Ferralsol and Rhodic Ferralsol, from the southeast region of Brazil. The pore distribution analysis technique from impregnated soil blocks was utilized for this purpose. The 2D image acquisition was carried out by using a CCD camera coupled to a conventional optical microscope. After acquisition and treatment of images, they were processed and analyzed by the software Noesis Visilog 5.4® (chosen as the reference program) and ImageJ. The parameters chosen to characterize the soil voids were: shape, number and pore size distribution. For both soils, the results obtained for the image total porosity (%), the total number of pores and the pore size distribution showed that the Image J is a suitable software to be applied in the characterization of the soil sample voids impregnated with resin.

As ações antrópicas, como os sistemas de uso e manejo do solo, promovem alterações em sua estrutura. Estas alterações podem ser restritivas ao desenvolvimento das plantas em manejos do solo que envolva sua mobilização, tendo seus efeitos negativos potencializados pela maior intensificação de uso. O objetivo deste trabalho foi avaliar os atributos físico-hídricos de um Latossolo Bruno argiloso em sistemas integrados de produção sob distintos manejos de solo. Para isso avaliou-se a camada superficial (0.0-0.10 m) e subsuperficial (0.10-0.20 m) do solo nos sistemas de cultivo convencional (CT), mínimo (MT), plantio direto (NT) e plantio direto escarificado (CNT) sob diferentes usos da cultura do azevém [planta de cobertura (C), pastejo (G) e silagem (S)]. Determinou-se a densidade (Db), porosidade total (TP), macro (Ma) e microporosidade (Mi), as curvas de retenção de água (CRA) e a retenção de água em função do raio de poro (r). O uso do azevém como C proporcionou menores Db e Mi e maiores TP e Ma nos sistemas CT, MT e CNT. Não foram verificadas diferenças entre G e S para todos os manejos, em ambas as camadas de solo. As CRA da camada superficial entre CT, MT e CNT apresentaram comportamento semelhante. No NT, C proporcionou uma maior retenção de água. Entretanto, G e S proporcionaram maior a retenção de água em função dos raios de poros no NT.

Anthropic action, such as the soil use and management systems, promote changes in the soil structure. These changes might hamper the development of plants in soil management practices that involve its mobilization, and the negative effects might be increased due to intensive use. The aim of this study was to evaluate the physico-hydrical properties of a Haplohumox in integrated production systems under different soil managements. The soil superficial (0.0-0.10 m) and sub-superficial (0.10-0.20 m) layers were evaluated in the different systems: conventional tillage (CT), minimum tillage (MT), no-tillage (NT) and chiseled no-tillage (CNT), taking into consideration the annual ryegrass cropped for different uses [cover crop (C), grazing (G) and silage (S)] during the winter. Soil bulk density (Db), total porosity (TP), macro (Ma) and microporosity (Mi), water retention curves (SWRC) and water retention due to pore size (r) were determined. The annual ryegrass used as C produced lower Db and Mi and higher TP and Ma in CT, MT and CNT systems. No difference was verified between G and S in any of the management systems or soil layers. The superficial layer SWRC presented similar behavior regarding CT, MT and CNT. Under NT, C resulted in higher water retention. However, G and S provided higher water retention due to the pore size in this system.

Um tomógrafo computadorizado (TC) de raios gama de primeira geração equipado com fonte radioativa de 137Cs foi usado no estudo de mudanças na estrutura do solo pelo tráfego de implementos agrícolas. Amostras com volume de 55 cm³ foram coletadas na superfície (0-10 cm) de um solo argiloso. Alterações significativas na estrutura do solo ocorreram após duas passagens da roda de um trator com importantes diminuições na sua porosidade. Os dados de TC permitiram uma contínua análise das distribuições de densidade do solo e porosidade para camadas de 1,25 e 1,20 mm, o que não pode ser obtido nos métodos tradicionais comumente usados em física do solo.

A first generation gamma-ray computed tomography (CT) equipped with a 137Cs source was used to investigate changes in soil structure due to agricultural machinery traffic. Core samples with volume of 55 cm³ were collected at the surface (0-10 cm) of a Brazilian clayey soil. Significant alterations in soil structure occurred after two passages of tractor wheels, with important decreases in soil porosity. CT data allowed a continuous analysis of soil bulk density and also soil porosity distribution for 1.25 and 1.20 mm layers, which cannot be provided by traditional methods commonly used in soil physics.

A tomada de água pelas raízes de espécies vegetais cultivadas vem a ser uma resposta fisiológica da planta ao processo de perda de água através de seus estômatos. Conhecer a transpiração possibilita a determinação da quantidade ideal de água a ser aplicada no momento certo com vistas à maximização da produção com proteção ambiental. Como a medida direta da transpiração no campo, principalmente em árvores, constitui procedimento que envolve dificuldade operacional e custo relativamente elevado, propôs-se neste estudo uma metodologia de cálculo da transpiração diária de macieiras e citros a partir de variáveis do meio físico e da planta. As variáveis de entrada do modelo proposto compreendem a temperatura do ar, a umidade relativa do ar, a duração do fotoperíodo e a área foliar da árvore. Taxas de transpiração estimadas com base no gradiente de potencial da água entre o ar atmosférico e a câmara estomática das folhas foram comparadas com valores diários de fluxo de seiva de macieiras e citros determinados através do método de balanço de calor nas regiões de Bordeaux, sudoeste da França, e de Piracicaba, SP, Brasil. O método apresentou estimativas altamente comparáveis às medidas de fluxo de seiva em pomares de macieiras e citros irrigados por gotejamento, visto que os coeficientes de determinação das equações de regressão obtidas foram superiores a 0,93, podendo-se inferir que a lâmina de irrigação a ser adotada durante o ciclo de desenvolvimento dessas espécies frutíferas pode ser estimada com elevada precisão a partir do conhecimento do regime vigente de elementos meteorológicos e da densidade de cobertura vegetal.

The uptake of water from the roots of crops comes to being a physiological response of the plant to the water loss process through its stomata. Getting to know the daily transpiration rates throughout the phenological cycle allows for the application of the ideal amount of irrigation water at the right moment to maximize production with environmental protection. Since transpiration direct measurements at the field, mainly for trees in general, are to be of operational difficulty and relatively high cost we came up with a methodology that allows one to calculate the daily transpiration rates of apple trees and citrus orchards from variables of both the physical environment and the crop. The input data of the proposed model are air temperature, air relative humidity, photoperiod duration, and leaf area. Estimated transpiration rates based on the water potential gradient between the air and leaf approach were comparable in apple trees and citrus orchards. Sap flow daily values were obtained by means of the heat balance method at Bordeaux, France, and Piracicaba, SP, Brazil. All the coefficients of determination of the regression equations obtained herein were higher than 0.93. This allows one to calculate the amount of irrigation water to be applied throughout the crop growing seasons with a high precision as a function of meteorological data and crop covering density at the sites in the study.