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The cultivation of Hevea brasiliensis (rubber) is promoted as a productive and ecological alternative, especially in agroforestry systems, although research is still required to address its impact on soil chemical conditions. This study aimed evaluate the possible effects of five types of land use on the chemical properties of horizons A and B in soils of the Colombian Amazon: agroforestry system of H. brasiliensis with timber and fruit trees, agroforestry system of H. brasiliensis associated with stubble, H. brasiliensis monoculture, secondary forest as positive control and native grass as negative control. The conditions of pH, exchangeable aluminum, organic carbon, potassium, phosphorus, calcium, magnesium, base saturation and cationic exchange capacity were evaluated. Similarities in soil chemical properties were found between secondary forest, agroforestry systems with fruit trees and agroforestry systems associated with stubble. The H. brasiliensis monoculture did not present significant differences with the native pasture. The pH was the only variable affected by soil use, while the percentage of organic carbon and the contents of phosphorus, calcium, magnesium and potassium changed depending on the A and B horizons, demonstrating that the variability of the chemical fertility of the clay soils of the Amazon are more related to the characteristics of their horizons than to the type of land use. [ABSTRACT FROM AUTHOR]

In recent years, there has been great interest in sustainable construction, which has led to an increased interest in 3D printing or additive manufacturing. However, the use of this technique with conventional materials is not enough to reduce the large environmental impact generated by the construction sector. Although most of the research and advances are focused on the 3D printing of Portland concrete, this review has been oriented towards the 3D printing of building materials based on soils and clays, which can provide an affordable (as it is a locally available material in many regions of the planet), environmentally sustainable, and low-cost approach, which is highly beneficial for housing construction. This paper has been oriented towards the search of scientific literature and prototypes that have been elaborated using ancestral materials, such as soil-clay-sand-sand-fibers like straw and water, for the elaboration of constructive pieces such as 3D printed walls or adobes. The objective of this paper is to close the gap on the use of mixtures based on soils, which, although they seem to have been fully studied for several centuries, to date their application in 3D printing is reduced. Readjustments in properties of soil mixtures such as fluidity for pumping or extrusion, buildability and good working time are variables that are reported in this paper. In addition, this review describes the mixtures that have been developed for 3D printing from soils and clays, and the main characteristics that have been found. Finally, the challenges that still remain for the blends to be applied on a massive industrial scale are presented. [ABSTRACT FROM AUTHOR]

This study on the effectiveness of lime as a stabilizing additive in clayey soils addressed the uncertainty regarding its specific efficacy, taking into account the degree of soil expansion and application percentages. The research focused on three geotechnical sectors in the Manabí region, where the presence of expansive soils impacts the stability of civil engineering structures. Significant geotechnical issues were identified in expansive soils, including their high plasticity and volumetric changes associated with moisture. The limited bearing capacity of the subgrade is a recurring challenge in pavements. Intervening to improve these soils was deemed essential, and the study focused on evaluating the effectiveness of lime under different degrees of expansion. A mixed approach, predominantly quantitative, was adopted, conducting laboratory tests to establish the efficacy of lime. The results contributed to a robust understanding of soil stabilization, suggesting that adjusting lime percentages is crucial to optimizing stabilization without compromising soil compaction. These findings were valuable for informing future construction projects in areas with expansive soils, emphasizing the importance of considering geotechnical variability for effective technical and economic solutions. [ABSTRACT FROM AUTHOR]

The northern coastal strip of Venezuela with a semiarid climate presents conditions for the development of extensive areas with the presence of expansive clays, and, this is the main pathology of its communication routes due to deformation in the surrounding civil works. This contribution characterizes the presence of expansive clays in northern Venezuela in 81 samples distributed in several states of the country. The study included the determination of geomechanical properties through field work and laboratory tests by Atterberg limits, consistency indices and expansion tests as well as the relationship between the indexes and information from edometer tests. The soil grain size is mainly fine (silts and clays), in the Anzoátegui state the average content of fine grains is 86%, while in Falcón and Miranda they are a little lower, 82% and 67%, respectively. In general, the plasticity index (PI) of these expansive clays is high, with an overall average of 23, although the region of Falcón state presented a moderate average (18). The correlations between the expansion pressure and the PI showed a high correlation. These results corroborate that the criterion used to evaluate the Expansion Potential of a clay soil based on the PI proposed by Chen (1988), is a fairly adequate criterion to be used in the study and identification of the expansive behavior of these types of soils. [ABSTRACT FROM AUTHOR]

The main goal of this research is to carry out an analysis of the influence of rainfall on the stability of the slope downstream of a homogeneous earth dam, with a 15-meter embankment height and drainage at the foot of the slope. A sample of 10 unsaturated clayey soils was determined to form the embankment, and rains were applied for 12 and 24 hours, for return periods of 5, 10, 25 and 50 years. The behavior of the safety factor and the failure time are evaluated. In addition, the influence of porosity and permeability of soils on stability is determined. [ABSTRACT FROM AUTHOR]

This research focused on the implementation of different species to evaluate their efficiency in soils disturbed by clay mining. A part of the land was taken and a physical-chemical and microbiological characterization was made to know the conditions of the soil under study before applying the species, then it was divided into four plots of equal measures, of 1.5x1 m, one control and three in which we applied the respective species, this with the objective of evaluating the efficiency of the interaction of the species in the soil contaminated by mining. This study revealed the great capacity of grasses (Maize, star grass and brachiaria grass), and Fabaceae (Yaguaro and Acacia Riparia Kunth), to provide organic materials and nutrients that allowed the evaluation of the efficiency or reactivation of the contaminated soils. It should be noted that the one with the highest efficiency was plot three. [ABSTRACT FROM AUTHOR]

Many studies have shown the need in the Venezuelan oil industry to implement viable alternatives in the field of pipeline integrity management. Thus, the aim of this work is to propose a prediction model for the external corrosion rate of burned transmission pipelines in a crude oil production field with clay soils, Incated in the west of Zuha State in Venezuela. After the collection, revision and classification of soil and operating parameter data in the field, a definition of input and output variables was carried out, used to generate 2 models, one regression type and the other classification type. For the neural network model, a low regression fit (R) of 6.62% and an RMSE of 2.13 were obtained, indicators of low model efficiency due to the restrictions of the data provided and sample stre. On the contrary, for the decision tree classification model, un accuracy of 98 141% was obtained, when classifying the corusion rate in seventy ranges. This clasification tree model will serve as a starting point for subsequent research to dleve deeper into the area. [ABSTRACT FROM AUTHOR]

The investigation has the aim of finding the effect and adequate proportion of the hemp fiber of 4 cm in length, in the mechanical and resistivity properties of a clayey soil. Properties investigated include optimum moisture content (wópt); the maximum dry unit weight, (γdmax), cohesion (c); friction angle (Φ), unconfined compressive strength (qu), and electrical resistivity (ρ). The modified Proctor compaction tests (ASTM D 1557-12), direct consolidated undrained shear, CU, for cohesive soils (ASTM 6528-17), unconfined compressive strength (ASTM D2166-16) and Wenner's four electrode test (ASTM G57-01l), were applied to three clay samples with differentproportions of hemp fiber; standard sample, Ap, of 100 % clay from the city of Tunja, sample with 0.5 % and 0.75 % hemp fiber, A0.5 %, and A0.75 %, in relation to the dry weight of the material. The results of this study indicate that the optimal percentage of hemp is 0.5 %, showing a decrease in compaction, and an increase in shear strength, electrical resistivity properties and unconfined compression properties; nevertheless, with a greater presence of fiber, there is destruction of the clayey soil. [ABSTRACT FROM AUTHOR]

In this paper, the application of geostatistical models to 71 tests with a dynamic probe super heavy DPSH Grizzly® carried out during the last 7 years over a wide area of the northern sector of the city of Punta Arenas is presented. This sector is characterized by having an extensive unit, composed of potentially liquefiable loose saturated sands, which is accompanied by other smaller units composed of organic soils and soft clays locally known as "mazacote". Geostatistics models allowed to obtain a spatial correlation of the tip resistance data of the dynamic penetrometer DPSH Grizzly®. Through Kriging geostatistical interpolation estimates, geotechnical units that make up the sector under study were identified as well as the most susceptible areas to the liquefaction phenomenon. The study was complemented with data from SPT tests, geological and geomorphological charts and calibrations to the dynamic penetrometer DPSH Grizzly®, undertaken during the execution and review of the tests. [ABSTRACT FROM AUTHOR]

The research was carried out in the Sugarcane Quarantine Station in Isla de la Juventud, during the cold season of 2010-2011, on an Alitic soil with low clay activity with the objective of evaluating the response of the cultivation of the onion before the combination of the Arbuscular Mycorrhizal Fungus (AMF), Glomus Hoi Like strain and the application of the bionutrient Fitomas E, in different doses (0.5 and 1  L/ ha), the inoculation of Glomus Hoi Like was carried out on the postures at the time of transplantation, as for Fitomas E, it was applied 15 days after transplantation. The set-up of the experiment was carried out using a randomized block design, with five treatments and four repetitions in plots of 6.40 m². Planting was done using the transplant technique, with postures with three to four true leaves formed and 16 to 18 cm. High. The phytotechnical activities were carried out as established by the technical instructions for the crop. During the development of the investigation, the variables of growth and yield (t/ha) were evaluated. The data was processed by analysis of variance and Duncan’s multiple range test was applied for p<0.05. It was concluded that treatment four, which consisted of the inoculation of the Arbuscular Mycorrhizal Fungus (AMF) Glomus Hoi Like + 1 L/ha Fitomas E applied 15 days after the transplant, favored the variables of growth and yield, with values of 42.6 t/ha [ABSTRACT FROM AUTHOR]

The amount and quality of carbon from forest litter present in the soil will depend on several factors, including species composition, management practices, plantation age, climatic conditions and soil texture, among several other factors. The aims of this research were to: i) quantify the labile organic carbon content in soils with Eucalyptus grandis plantations of the Mesopotamian region in Argentina and evaluate its relationship with the amount and type of litter; and ii) identify management, edaphic and environmental factors that may influence its variation. The study was performed on young and middle age plantations having soils with sandy and clayey texture located in the Gualeguaychú district, Entre Ríos, Argentina. To quantify the labile carbon in the soil, the soluble organic carbon was extracted with a 0.5M potassium sulfate solution. Soluble organic carbon concentration did not differ according to the age of the stands, with average values of 45.6 mg kg-1 in clay soils, and of 32.8 mg kg-1 in sandy soils, showing a positive association with clay content. The highest soluble organic carbon values were recorded during the summer months, and were positively related to the increases in the water-saturated pore space and the soil biological activity. We also verified a linear and positive relationship between the amount of initial fine litter and the increase of soluble organic carbon in the soil (R² = 0.41). The reported results provide explicit ranges of variability for total organic carbon, soluble organic carbon and carbon fluxes at local level; thereby contributing to further characterize carbon modeling in forest systems. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study, which compares the effect of the sensitivity against the cementation in the recovering of the stress-strain properties in clayey soils from "Sabana de Bogotá". The work methodology included three phases: (i) extraction of samples; (ii) properties assessment of the undisturbed samples; and (ii) stabilization and analysis of the resistance of the stabilized samples with cemented materials. An experimental plan, which included physical and mechanical tests, was developed. The plan had an emphasis on the assessment of the undrained shear strength and the elastic modulus through unconfined compression tests. The samples were compacted and stabilized with the addition of two solid chemical products, calcium carbonate and iron oxide. Results between natural, remoulded and stabilized were compared by means of statistical methods. Therefore, it was found that the use of iron oxide in this kind of soil allows obtaining stress-strain parameters close to the undisturbed state after the compaction process. [ABSTRACT FROM AUTHOR]

The soil is considered the largest carbon reservoir in nature after the oceans, its content has been studied mostly in forest ecosystems, leaving aside other important ecosystems such as high Andean natural pastures, whose plant cover is made up of species diversity, which occupy large areas. The objective of the research was to determine the influence of the altitudinal variability on the Soil Organic Carbon (SOC) storage capacity of the Stipa, Festuca and Calamagrostis species, as well as its relationship with the characteristics of the soils. 73 soil samples were extracted at 0.2 m depth, between altitudes of 4000 to 4410 m.a.s.l.; To determine the COS, the wet oxidation methodology was used. The results show that there is no significant difference in the accumulation of SOC of the species studied, its general mean is 364.33 ± 48.80 t ha-1 . The correlation coefficients between the amount of SOC and altitude, sand, silt, clay, temperature and organic matter were 0.84; 0.72; -0.30; -0.56; -0.82 and 0.91, respectively. As the altitude increases the COS content increases; the variation of sand and clay in the structure of the soil, influence this process, while low temperatures favor the accumulation of carbon according to the availability of organic matter. [ABSTRACT FROM AUTHOR]

This work evaluates the behaviour of clay soil mixture by adding stell waste/slag, comparering with the quality criteria to be a subgrade road. The behavior of the mixture of steel waste with kaolinite clay was established with a dosage matrix of global increase, in percentages of 25, 50 and 75% through sieve number 4. The results show that the steel waste works on cohesive materials, reducing plasticity by up to 0%, and increasing the California Bearing Ratio (CBR) value, by 378.92%. It is possible to conclude that the steel waste is an excellent complement for improving the physical and mechanical properties of kaolinite clay subgrade. In a first approximation, the most recommended dosage is 25%, because the reduction of resistance to compression and plasticity index was not as high as in other dosages, but it increases the CBR index and the density. [ABSTRACT FROM AUTHOR]

Changes in soil structure can be monitored in undisturbed soil samples through the micromorphometric analysis of thin sections. In this methodology, it is common that individual images (three to ten repetitions) are used and that they cannot be related in different scales between soil components; in addition, although a minimum study area is established, its representativeness in the soil components is unknown. The objective of this study was to quantify the soil constituent (pores, aggregates, and roots) and to compare the values obtained from individual images versus high-resolution mosaics from a complete thin section. Unaltered samples were collected in three soils with different clay contents (Entisols, Inceptisols, and Vertisols) and presence of maize roots in the same phenological development stage (physiological maturity). Three thin sections of each soil (5 × 7 cm × 30 μm 1865 mm2) were prepared and sequential images of 11.1× 7.4 mm (63 in total) were obtained at 2× magnification using a petrographic microscope and plane polarized light (PPL). The high-resolution mosaics (2.6 μm píxel-1) at a colour depth 24 bits (8 bits × 3 bands in standard RGB) were built using space operators; subsequently, three, five and ten images were randomly selected. The individual images and the mosaics were transformed by principal component analysis in ArcGis® and soil constituents were delimited according to their variances values. The results indicate that individual images are recommended only to quantify porosity or in homogeneous systems in structure and color, but not in heterogeneous systems where the data obtained show high variability. Even when the results are similar to those calculated in the mosaics, the dispersion of the data is high (variance 5 times greater than the mean) and with little representation. In contrast, high-resolution mosaics offer the total quantification of the thin section and soil components can be grouped into classes or categories to observe intra or inter relations in the soil system. In addition, the soil components can be related to different scales, for example macroaggregates and roots. [ABSTRACT FROM AUTHOR]

The Mechanics of Partially Saturated Soils, allows the analysis of the stability of slopes with the incorporation of variables not considered until now, from which, the phenomena of loss of stability can be seen from a new perspective. In the present investigation, the stability analysis of the slope upstream was made in a homogeneous earth dam, without berm, 22 meters of curtain height during the occurrence of a rapid drawdown product to a drought period of 90 days, considering the floor of the curtain under saturated and partially saturated conditions. For the computational model, the SEEP / W and SLOPE / W tools of the GeoStudio 2012 program are used, in which three cases with different clayey soils in the curtain are considered, including the characteristic curve of the same, a sandy foundation and a prism of drainage conformed by a high permeability gravel. The behavior of the safety factor in the upstream slope was analyzed, as the water level of the dam decreased and the influence of the laws of soil mechanics partially saturated in the occurrence of this phenomenon. There were no decreases in the safety factor that would jeopardize the stability of the structure. In addition, the drying branch of the characteristic curve is more appropriate to describe the process that occurs in the slope during the drought. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the percentage of water absorption and wetting in three soil types. It was used as experimental material to Acrylamide Polymer Potassium (PAP) and three floors of sand, loam and clay type. The amount of water (mL) and time (minutes) which absorbs 1g of PAP was measured. In addition, the wetting of PAP for each soil type by placing 1 g dry soil was evaluated previously soil moisture was measured before and after placing the PAP. The results indicate that the hydrogel absorbed per gram PAP about 103 mL, this absorption is increasing function of time reached, after this time turning point at 60 min the increase is not significant. It wetting had a variable increase depending on the type of soil, being 14.7, 17.4 and 14.5% for sand, loam and clay soils respectively. This wetting is obtained after about an hour. In saturated soil gels remain unchanged. However in a dry soil, the gels gives the contained water to the ground becoming part of the soil's water. [ABSTRACT FROM AUTHOR]

The objective of the study was to clean the kaolinitic clays in Cay Guam ore body through reverse acid leaching using chloride acid as a leach agent in order to clean the clay by eliminating the iron content. Techniques such as infrared and fluorescence spectrometry and X ray diffraction were applied during the characterization of the original raw material and after the reverse acid leaching process took place. The implementation of this method allowed extracting more than 98% of iron impurities, which resulted in obtaining a purer clay with silicon content of 60.48% and aluminum oxide of 49,50%. It was proved that the structure of the clay is not affected by reverse acid leaching and thus constitutes a method of beneficiation for kaolinites pigmented with iron. [ABSTRACT FROM AUTHOR]

The objective of this investigation was to define the zoning of soil liquefaction potential for the Guillermón Moncada Popular Council in the municipality of Santiago de Cuba. The engineering and geological conditions and seismic peculiarities favoring a seism to take place were assessed. The safety factor was re-calculated after determining possible maximum intensity values based on seismic magnitudes that can trigger the soil of the investigated area to liquefy. A scheme of the area's soil susceptibility to liquefaction was obtained. Based on this result, it was concluded that the sectors that are most likely to experience soil liquefaction if an earthquake of magnitudes ranging between 7,75 and 8 occurs are located towards the center-east of the Popular Council with sandy-clayey soils being predominant. This information is very useful for the location and planning of engineering construction works in the area. [ABSTRACT FROM AUTHOR]

Natural clayey materials from La Delta deposit located in Moa, Holguin was characterized through the techniques of atomic absorption spectrometry, X ray diffraction, thermo-gravimetric analysis and infrared spectroscopy to determine the puzzolanic activity. The clay thermal activation was completed at 650 °C and 750 °C. The calcination products were characterized through the grain size analysis and the specific surface in a particle analyzer. The compression resistance of the activated material was determined in the Portland cement/calcined clay system with a 70/30 ratio. The main chemical components identified were as follow: silicon dioxide; aluminum and iron associated to the mineral phases contained in the clayey material. The material obtained is a puzzolanic material with a high reactivity. This indicates that it has potential for use as a partial replacement for cement taking into account that its resistance is 75 % higher than that of the reference product. [ABSTRACT FROM AUTHOR]

The strip of Pand north of heavy crude oil represents the main source of Cuban hydrocarbons. About the reservoirs several thickness of clayey sediments are reported. Such sequences of these rocks characterize the base of Vega Alta formation providing a sealing character. Recently scanning electron microscopy with X ray microanalysis have been used as part of a methodology of analysis, developed for clayey seal rock characterization in thouse strip of land. This methodology consisted on the integration of the morphological and chemical information. These techniques were applied to drilling cores and outcrop samples. The results of the analysis allowed to get information about the nature of the seal rocks, which is important aspect to take into account for the hydrocarbon exploration. With the application of these techniques, clays belonging to the complex mixture illite, smectite were determined. The spectra obtained by x-ray fluorescence, corresponding to clayey rocks. The chemical composition evidence the nature of these rocks, where the major elements are silicon, aluminum, calcium and magnesium. These studies allowed a better characterization of the oil seal, and allowed more detailed studies, not only in the strip of land north and also in other areas, aspect which is the main objective of the present research. [ABSTRACT FROM AUTHOR]

The modification of the combined scarifier C 101 resulted in a new approach in the heavy clayey soils' preparation in the north of Villa Clara. A research was carried out in the primary labor, also called soil breaking, with the objective of evaluating some parameters of labor quality of three plows (C 101M, AT-90 and M 250) in surfaces with mounds and vegetables residues covering. The results suggested that the employment of the located primary tillage with the C 101M under those conditions showed better indexes of labor quality as regards the total one with the Multi-plow M 250 and the Disks-plow AT-90, due to the greater stability in the work depth and soil fragmentation. As to this factor, in the case of the C 101M, clods between 50 and 100 mm prevailed with 21%. According to the studied parameters about labor quality, the use of the located primary tillage with the C 101M in the conditions aforementioned is recommended. [ABSTRACT FROM AUTHOR]

The models developed for on the go soil compaction sensing taking into account the soil density and the moisture content, the depth and the soil resistance, these have been developed for sandy, silty and clay, but its accuracy is not known to predict compaction on the conditions of cuban soil. The goals of this study is to determine the validity of the equations developed for predicting soil compaction during the go sensing, in a Rhodic ferralsol western Cuba. To complete this objective was tested experimentally the validity of these models in the soil bin controlled conditions, for a wide range of soil conditions and operation of the sensor. The main results show that the prediction errors of the models analyzed (0,90 to 260%) inability to correlate the sensor readings with soil compaction, although the models developed by Mouazen are more accurate (e = 0,90 to 41%) that the models developed by Andrade (e = 8,15 to 260%). Soil moisture was variable in the prediction that more weight have in the predictions accuracy, being the forward speed the second variable of importance regarding the accuracy of the predictions, which is an indicator of the inclusion need in future prediction models. [ABSTRACT FROM AUTHOR]

The modification of the scarifier C 101 for the primary tillage of mound’s surfaces in heavy clay soil dedicated to sugarcane is presented. The fragmentation of the soil to different depth of work was considered for the determination of the number of scarifying arms, and the mound’s characteristics for the dimensions of the arrows. The results indicated that the soil braking to 0,1m of depth among step of scarifier in tandem didn’t showed significant differences regarding that of 0,07 and 0,13 m respectively, so according to the scarce effective depth of these soil and the mound’s profile, narrow in the crown and wide in the base, is recommended to modify the C 101 for the tillage under this conditions with three scarifier arms in tandem and stepped to 0,1 m, with arrows of 700, 800 and 900 mm of width of work. [ABSTRACT FROM AUTHOR]

Some design parameters of the stripe tillage implements in mound sufice are foundation. The mathematical modelling of these determined that increase of work depth in regard to the inter row space of 0,01…0,15 m and the fail incline angle in the transversal plane of 30°…50° diminishes the width of work of the arrow from 0,87m to 0,71 m. The distance between two scariier arms increase with the increment of the facing angles of the tool and of soil-metal friction up to 0,85 m, also the augment of these organs from two to four, reduces the distance among them to 0,3 m. it is recommended for the stripe primary operation in mound surfaces, with scariier in tandem, that the width of work of the arrow's scariier and the spaced out among these will be 0,87m and 0,85 m respectively. [ABSTRACT FROM AUTHOR]

The finite elements method has been widely used in the simulation of the soil mechanical response. The constitutive models are the mathematical support core of this method and Duncan and Chan's is one of the most used. Therefore, the aim of this paper is to determine accuracy in the prediction of three Cuban clay soils' relationship strain vs. deformation. The soils mechanical properties are determined and the constitutive equations are made in the software Mathcad 14 to accomplish this goal. The results show the model has a large capacity to predict accurately the relationship strain vs. deformation of these soils when there is a plastic failure. However, the model is not able to predict the tensions changes caused by softening or hardening deformations. [ABSTRACT FROM AUTHOR]

An experiment was mounted under a heavy clay soil in order to define the place for the application of stripe tillage either in row or in the inter-row space according to the physical soil properties. Structure factor FE, aggregate stability AE and permeability index K was evaluated. It was found that: the FE in row at 0 to 20 cm showed significant different respect to both depths of inter-row space in 1,2 and 2% respectively, also in row at 20 to 40 cm in regard to the same depth of inter-row in 1.3%; in other side It was found significant difference in AE in the row at 0-20 cm in respect to both depth of the inter-row in 3.6 and 5.4% respectively and between the row and the inter-row at 20 to 40 cm in 3,1% too. The values of K to the row at 0 to 20 cm showed significant difference in regard to the other depth of that zone and both depth of the inter-row in 0,07, 0,08 and 0,14 respectively, and also among the row at 20 to 40 cm and the inter-row at 0 to 20 and from 20 to 40 cm of the last one in 0,06 approximately. The tilling located is recommended in the row of sugar cane. [ABSTRACT FROM AUTHOR]

This article presents a research program developed for the evaluation and determination of the Morh-Coulomb model parameters and the Hardening Soil model parameters in clay soils. The methodology includes the analysis of some correlations, basic characterization soil tests and undrained compression triaxial tests carried out on reconstituted soil samples in laboratory (kaolin). From the obtained parameters the behavior stress-strain was simulated in the element finite software PLAXIS, examining the performance of the models by comparing the numeric calculation results with the experimental soil behavior. For the sets of considered model parameters, the analysis shows that the computational results have a reasonable agreement with the experimental results, appreciating a better approximation to the behavior described by the tests in the simulations performed with the Hardening Soil model, whose results evidence a better grade of adjustment to the typical hyperbolic relationship of the soil tested. In addition, the concluding results represent an important validation of the methodology program developed. [ABSTRACT FROM AUTHOR]

The preliminary results of disc trash mulcher test for the harvest residues management in the heavy clay soil of the north cost of Villa Clara indicated that: disks of 32" and 28" diameter show greater trash movement between 0,65 and 0,85 kg/m² in regard to 26" with and without vertical angle (VA) against to the plough; the greater trash movement up to 0,36 kg/m² is performed with horizontal angle (AH) among 35 and 45° to the 32" disk; and to the 28" and 26" disks between 40 and 45° with 0,35 and 0,28 kg/m² of maximum trash movement respectively; vertical angle among 15 and 25° in the 26", 28" and 32" shown better result up to 0,48; 0,68 and 0,77 kg/m², respectively; use smooth disks preferably. The design of slight work organs is recommended and of low economic cost for the displacement of the vegetable residuals toward the sugar cane array in heavy clay soil. [ABSTRACT FROM AUTHOR]

The main objective of soil improvement by drying is water balance regulation in the sense of decreasing water reserves, with the help of a group of agricultural and engineering reorganizing measurements. The man, in his daily work, often comes up against the need of modifying or remaking some natural—climatic, hydrological and soil conditions, among others. Some lands are naturally leveled, they have natural drainages and deep plough layers, they consist of naturally-blended clay soils with an appropriate amount of sand, they can be naturally-irrigated grasslands or covered by a loam layer; others should be leveled and require artificial drainages, the arable layer should be artificially deepened, the right proportion of clay and sand must be artificially created, that is, they are grasslands without natural irrigation that should be modified by working on it, to achieve the same conditions of other improved soils through water improvement by drying. [ABSTRACT FROM AUTHOR]

At the end of 2004, a study was carried out in order to find the best combination of several implements during the strip tillage in the heavy clay soil at the north of Villa Clara. This technology was compared with minimum land preparation of all surfaces in: field capacity, cost, fuel and time consumption, and also diameter, height, agricultural yield and population of stem. During the results analysis was found that the strip tillage increases field productivity, requiring less than the other analyzed in 2,07 h/ha, it saves fuel and operation costs at a rate of 28 liters/hectare and 46,77 peso/ha respectively, the field is ready to be planted a month before and population and sugar cane yield is significantly superior in 7 320 stem/ ha and 9,21 t/ ha. [ABSTRACT FROM AUTHOR]

The influence of minimum tillage in regard to clod size and worked area of soil were determined. The investigation was carried out for sugar cane mound plantation in heavy clay soil. Five treatments were studied, three of them below to stripe tillage base on the use of C-101 implement (with or without modification) and the slight disks arrow (so call «Rome») and the rest to the whole surface minimum tillage using the disks plough and heavy disks arrow also. The conclusion is as follow: the stripe tillage treatments gave adequate clod size for mounted sugar cane plantation, two slight disks arrow after C-101 was enough to guarantee the seed bed conditions, the C-101M had better result in clod size and worked area in stripe tillage, and this one works only the 70 % of the soil profile in regard to whole surface minimum tillage. [ABSTRACT FROM AUTHOR]

On along-term essay under direct drilling, the evolution of the physical properties of a clay loam soil, such as distribution by origin of soil porosity, has been assessed during two growing seasons. The grain crops in each growing season were spring barley and winter barley, respectively. Soil physical properties were measured on a 2 m length transect located on a perpendicular line to the direction of vehicular traffic for field operations. Five sampling opportunities in each crop cycle, were used to measure the variables. Structural soil porosity, due principally to shrinkage and swelling cycles, was assessed in the 0 to 35 cm depth soil profile. This natural process seemed to be sufficient to guarantee good drainage and normal crop development, unless in the moisture content range included in field capacity. [ABSTRACT FROM AUTHOR]

In this study, the required draft of an integral, reversible three-disks plow was studied on a loam clay soil. The experimental design was a random, three complete block design with three repetitions. The factors under study were three levels of gravimetric humidity in soil, 10,02, 19,74, and 22,39 %, and three speeds, 4,55, 5,27, and 7,34 km · h-1. The response variables were work depth, cross-section area, sliding, required specific draft, draft efficiency, and specific draught resistance to ploughin. The results show that when the gravimetric humidity of the soil was at 19,74 %, variables FTHER and REA showed the lowest values, but EFTHER showed the tallest value at same level humidity. Models that adequately estimate FTHER and REA were obtained. [ABSTRACT FROM AUTHOR]

This study was realized to evaluate the evaporation on different type of soil mositened with magnetized water. Five tests were realized, a sandy and clay soil were moistened with distilled water, tap water and a 0,026 M NaCl solution. Magnetic treatment of water took place by circulation into a device with 6 magnets for different times, 30, 60 and 120 minutes. The evaporation on both sandy and clay soil moistened with distiled water subjected to magnetic treatment for 60 minutes is significantly less than the control; the same effect is observed when the test is realized using tap water. [ABSTRACT FROM AUTHOR]

Researches with the objective to find the causes and to characterize the excess moist of the soils in the north of Villa Clara were carried out for several years. These soils occupy approximately 67 000 hectares here, where sugar cane is produced for 7 sugar factories. The excess of moisture persists in these soils much time after the showers. The fundamental causes of the excess moist in these areas are: the physical properties of the soil which originate the impermeable profile with hydraulic conductivity practically null existing below 40 cm deep, the meager gradient generally lower to 0,003, and the unsuitable distribution of the rains. The general criterions were established in order to solve the problems of drainage. [ABSTRACT FROM AUTHOR]

The researches were carried out at heavy clay soils in the North of Villa Clara. Four combined alternatives are proposed for the drainage. The better solution was the construction of slots or soil drains 5 cm wide and 70 cm deep below each cane row, plus collector pipes spaced 60-120 m and at a depth of 0,90-1,10 m. The slot drains are filled during their construction with soil from the ploughed profile or other organic or permeable material. Its principal benefits are yield increase of 30-150 %, and reduction of the time lost to 50 % because of rainfalls during the harvest. The investment fluctuates 300-950 USD /ha and it is redeemed like average in 3 crops. [ABSTRACT FROM AUTHOR]

The characteristics of the mound surface of interest for the design of the work member for the stripe tillage are presented, as the mound's height average in fields between 6 and 7 years was of 0,17 m and the width average from the tope to 0,05; 0,1 m and in the base of 0,51; 0,73 and 0,85 m, respectively. The distribution of the stump on the flowerbed, from its center and in the traverse plane at 0,15; 0,35 and 0,45 m in 10 lineal meter were of 54,3; 31,9; and 13,8%. The pattern that is adjusted to determine the mound's height in function of the horizontal distance is Hc = 0,016 - 0,358*4. [ABSTRACT FROM AUTHOR]