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This paper shows the implementation of a network of wireless sensors for the measurement of microclimatic variables in the Relicto Vegetal Cedro Rosado located within the University of Quindío. The network has three sensor nodes that allow the acquisition of data corresponding to the variables: temperature, relative humidity, atmospheric pressure, solar radiation, soil moisture, wind speed, wind direction and precipitation. The acquired data is processed and sent to a Gateway using a wireless network with DigiMesh protocol using the 900 MHz free band, the data is received by a Gateway that is connected to a computer for later processing in a technological platform. [ABSTRACT FROM AUTHOR]

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The objective of this work is to show the performance of an Ensemble Kalman Filter, the most disseminated among the Monte- Carlo based filters, for improving the estimation of the soil moisture profiles, by assimilating of near surface measurements of this state variable in a model based on the Richards equation. As part of this general purpose we also show the impact of the size of the ensemble of the state variables on the assimilation efficiency. In this study we estimate the "actual" dynamics of a moisture profile, generated from a model realization using synthetic data, considering perturbed values of the inputs and parameters adopted in the "actual simulation". The assimilated "measurements" are obtained by disturbing the actual daily value of pressure heads in the first node of the discretized profile. The application of the filtering tool with an ensemble size of 50 members allows retrieving the actual profile after only ten assimilations, despite of the high incorporated uncertainty. The study shows that the method is able of accurately predicting the actual moisture dynamics even with only ten members of the ensemble. The advantages of this method over other analogue ones, as well as the great capabilities for its introduction in the water management of Cuban soils are also depicted. [ABSTRACT FROM AUTHOR]

To develop this study, the resistance penetration in a clay loam soil was evaluated, after two years of management using conventional tillage (CT), vertical tillage (VT) and non-tillage (NT) with oat. The experiment took place from August 2010 to June 2012. The resistance penetration was determined through a manual cone penetrometer of the brand FIELDSCOUT SC 900; samples were taken at the beginning of the experiment to know the conditions of the plot because it had not been worked for several years, the baseline for the resistance penetration was 3 768,50 kPa and a bulk density of 1,28 g⋅cm-3. For the final data analysis the statistical software R 2.9.0 was used with a random block design and the package GS+ 5.1 to generate the diagnostic maps. The obtained results in the ANOVA for the 'f value' was 0,6020 for the tillage treatments and an average value of 1 500,10 for CT; 1 532,50 for VT and 1 718,60 for NT in a depth from 0 to 30 centimeters, without significant difference between treatments. The bulk density obtained at the end of the study, was of 1,20 g⋅cm-3 for CT; 1,22 g⋅cm-3 for VT and 1,15 g⋅cm-3 for NT. The tillage systems do not show changes according to the applied force to the soil at the moment of fail, because it is entirely related with the bulk density and the soil moisture. [ABSTRACT FROM AUTHOR]

Soil moisture is a key state variable in the dynamics of dissimilar processes and natural phenomena. This, together with the development of new methods of estimation of this variable at different scales in space- time, has led to the use of assimilation techniques to improve their estimates. The aim of this paper is to illustrate the potential of such tools in the estimation of soil moisture profiles from the assimilation of surface moisture values in a simulation model. To this end is performed a synthetic study based on the use of Richards's equation for modeling the movement of water flow in the soil. The use of assimilation technique significantly reduces the error estimated profiles with respect to the real ones, and with it avoiding the possible divergence of the solution. In particular the technique Kalman Filter assimilation obtained superior results, in less time, with respect to the technique of Direct Insertion assimilation. [ABSTRACT FROM AUTHOR]

The objective of this paper was the evaluation of the irrigation technology and the irrigation regime applied to the crop of potato in the field 14 of agricultural cooperative #2 belonging to the enterprise "Valle del Yabu" during the period 2008-2009. The irrigation technology was an electric central pivot model Western, which worked with good uniformity. The applied water depths were in general very small and with very short irrigation intervals those regime caused an excess of turns of the central pivot in the field, with problems of blockages and wash of chemical products. The soil moisture was measured by means of soil samples, tensiometers were also installed. The depth of 273 mm of water applied in the whole cycle was enough for the crop, but deficiently distributed. Starting from the water balance, the irrigation depths were recommended by phenological phases and also the irrigation intervals. The yield of tubers was of 30.37 t/ha with favorable economic indicators for the cooperative #2 [ABSTRACT FROM AUTHOR]

In a clay soil (vertisol), the primary preparation was done with a multiplow M-250; different assessments were conducted in different intensities and traffic conditions ballast tractor model JD.6603 and air pressure in the tires. The results in this type of soil during drought in the first 15 cm deep showed that, compaction is not seriously affected by the intensity of traffic in relation to conditions control, however resistance to penetration (Rp) given in kPa between replicates were highly significant, as well as levels from 5 to 15 cm and 30 to 45 cm deep, were significant (5%). Tractor ballast by number of passes, interaction was significant (5%) in the level from 30 to 45 cm. The comparison between treatment means showed that there were no statistical differences, but this behavior and its digital line with the variables ballast and air pressure used in the tractor tires showed numerical differences. In correlation analisis of the value -0.42 was highly significant between Rp (15cm) and Rp (45cm) variables. The bulk density was well below (1,30 g/cm³) at different intensities transit tractor regarding shown by the witnesses (1,41 g/cm³). [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the influence of three physical-chemical parameters on microbial activity of farm soils under controlled laboratory conditions (18% humidity, 27.5 °C and pH 7.8). Microbial activities were quantified by carbon dioxide production and dehydrogenase activity. Three different essays for 4 moisture percentages (v/w): 5.0%, 10.0%, 15.0% and 18.0%, 4 temperatures: 8.0 °C, 21.0 °C, 27.5 °C and 37.0 °C, and 4 pH values: 4.0, 6.1, 7.8 and 8.2 were evaluated. A Completely Randomized Design (CRD) was used for each essay consisting of four treatments and four replicates per treatment. The highest values on microbial activity [0.097 mg CO2⋅g-1⋅h-1 and 173.09 µg formazán⋅g-1⋅(24h)-1] were obtained at 18% humidity. It was found out that a temperature of 27.5 °C was optimum for carbon dioxide production [0.140 mg CO2⋅g- 1⋅h-1], and 37.0 °C for dehydrogenase activity [156.78 µg formazán⋅g-1⋅(24h)-1]. A near to neutral pH (7.8) was established as optimum [0.055 mg CO2⋅g-1⋅h-1and 171.19 µg formazán⋅g-1⋅(24h)-1]. [ABSTRACT FROM AUTHOR]

Critical state constitutive models are among the most employed for soil compaction simulation. This paper has the objective to determine the influence of moisture content on elastic-plastic parameters, which are used as data, for soil compaction modeling in finite elements methods. Triaxial and uniaxial compression tests were carried out to remoulded samples, with a bulk density of 1,1 Mg⋅m-3 and gravimetric moisture contents of 25; 35 and 40 kg⋅g-1 . The results show that moisture content has significant influence on elasticity module behavior, in the critical state slope and the slope of normal compression line, not being this way with the slope of rebound line. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to evaluate the effect of soil environment on yield and response of three wheat cultivars to fertilization with three doses (0, 40 and 120 kg ha-1). The differences were analyzed with analysis of variance and Fisher's LSD test. Gross margins of each treatment were calculated. All four factors tested in this experiment (site, environment, cultivar and fertilization) had a significant influence on crop performance. Yield and fertilization response were related to water availability which differed among environments. The yield component that most affected yield was the number of grains per square meter, showing strong variability among treatments (5000 to 15000 g m-2). These differences produced a wide range of variation in gross margins between environments, where a negative effect of fertilization in the more moisture limited environment could be observed, while in those with less moisture restrictions a positive contribution of fertilization to gross margin was found. [ABSTRACT FROM AUTHOR]

This work shows the results of use of solid displace measurement devices for Vertisoils moisture estimation in La Habana and Granma provinces. In these studies it was taken into account that for know hydric status of this kind of soils, the better way is in situ and no destructive measurements. The swelling clay soils are very difficult to manage due fundamentally to their low physic fertility; that's why they are highly inclined to erosion and inundation in raining season. Due to these restrictions, their total agricultural potential generally does not obtain. It's necessary to use special technologies adapted to these soils characteristics. The key to obtain an efficient agriculture on this soils is to understand their properties and processes enough well to be able to create ways to excel this restrictions. [ABSTRACT FROM AUTHOR]