Porous Soil Structure as Heterogeneous Complex Networks

In this paper we present a complex network model based on a heterogeneous preferential attachment scheme as a new way to quantify the porous structure of soils and to relate them with soil texture. We consider the pores as nodes, the properties of which, such as position and size, are described by fixed states in a metric space. An affinity function is introduced to bias the attachment probabilities of links according to these properties. We perform an analytical study of the degree distributions in the model and develop a numerical analysis of the degree distributions in the model for a combination of parameters corresponding to eleven empirical soil samples with different physical properties and five different textures

A Program for Fractal and Multifractal Analysis of Two-Dimensional Binary Images. Computer Algorithms versus Mathematical Theory.

In this paper we present a tool to carry out the multifractal analysis of binary, two-dimensional images through the calculation of the Rényi D(q) dimensions and associated statistical regressions. The estimation of a (mono)fractal dimension corresponds to the special case where the moment order is q = 0

Mulch materials in processing tomato: a multivariate approach.

Mulch materials of different origins have been introduced into the agricultural sector in recent years alternatively to the standard polyethylene due to its environmental impact. This study aimed to evaluate the multivariate response of mulch materials over three consecutive years in a processing tomato (Solanum lycopersicon L.) crop in Central Spain. Two biodegradable plastic mulches (BD1, BD2), one oxo-biodegradable material (OB), two types of paper (PP1, PP2), and one barley straw cover (BS) were compared using two control treatments (standard black polyethylene [PE] and manual weed control [MW]). A total of 17 variables relating to yield, fruit quality, and weed control were investigated. Several multivariate statistical techniques were applied, including principal component analysis, cluster analysis, and discriminant analysis. A group of mulch materials comprised of OB and BD2 was found to be comparable to black polyethylene regarding all the variables considered. The weed control variables were found to be an important source of discrimination. The two paper mulches tested did not share the same treatment group membership in any case: PP2 presented a multivariate response more similar to the biodegradable plastics, while PP1 was more similar to BS and MW. Based on our multivariate approach, the materials OB and BD2 can be used as an effective, more environmentally friendly alternative to polyethylene mulches

Multifractal analysis of the pore- and solid-phases in binary two-dimensional images of natural porous structures

We use multifractal analysis (MFA) to investigate how the Rényi dimensions of the solid mass and the pore space in porous structures are related to each other. To our knowledge, there is no investigation about the relationship of Rényi or generalized dimensions of two phases of the same structure

Sum Insured Determination for Cereal, Citrus and Vineyards in the Spanish Agricultural Insurance System.

In general, insurance is a form of risk management used to hedge against a contingent loss. The conventional definition is the equitable transfer of a risk of loss from one entity to another in exchange for a premium or a guaranteed and quantifiable small loss to prevent a large and possibly devastating loss being agricultural insurance a special line of property insurance. Agriculture insurance, as actually are designed in the Spanish scenario, were established in 1978. At the macroeconomic insurance studies scale, it is necessary to know a basic element for the insurance actuarial components: sum insured. When a new risk assessment has to be evaluated in the insurance framework, it is essential to determinate venture capital in the total Spanish agriculture. In this study, three different crops (cereal, citrus and vineyards) cases are showed to determinate sum insured as they are representative of the cases found in the Spanish agriculture. Crop sum insured is calculated by the product of crop surface, unit surface production and crop price insured. In the cereal case, winter as spring cereal sowing, represents the highest Spanish crop surface, above to 6 millions of hectares (ha). Meanwhile, the four citrus species (oranges, mandarins, lemons and grapefruits) occupied an extension just over 275.000 ha. On the other hand, vineyard target to wine process shows almost one million of ha in Spain

Comparison of fractal dimensions based on segmented NDVI fields obtained from different remote sensors.

Satellite image data have become an important source of information for monitoring vegetation and mapping land cover at several scales. Beside this, the distribution and phenology of vegetation is largely associated with climate, terrain characteristics and human activity. Various vegetation indices have been developed for qualitative and quantitative assessment of vegetation using remote spectral measurements. In particular, sensors with spectral bands in the red (RED) and near-infrared (NIR) lend themselves well to vegetation monitoring and based on them [(NIR - RED) / (NIR + RED)] Normalized Difference Vegetation Index (NDVI) has been widespread used. Given that the characteristics of spectral bands in RED and NIR vary distinctly from sensor to sensor, NDVI values based on data from different instruments will not be directly comparable. The spatial resolution also varies significantly between sensors, as well as within a given scene in the case of wide-angle and oblique sensors. As a result, NDVI values will vary according to combinations of the heterogeneity and scale of terrestrial surfaces and pixel footprint sizes. Therefore, the question arises as to the impact of differences in spectral and spatial resolutions on vegetation indices like the NDVI. The aim of this study is to establish a comparison between two different sensors in their NDVI values at different spatial resolutions

Incidencia de los Robos y Hurtos en el Sistema de Seguros Agrarios Español.

Este trabajo se estudia la viabilidad técnica de incorporar al actual Sistema de Seguros Agrarios Español la cobertura de los robos y hurtos en el medio rural, calculando la prima pura base (Ppb) para todas las producciones agrícolas, ganaderas y medios de producción asegurables dentro del sistema de los Seguros Agrarios Combinados. Los resultados indican que los robos se producen con una mayor influencia sobre los elementos de los riegos por aspersión y de los invernaderos, y la Ppb en consecuencia es la más alta de todos los bienes asegurables. Les siguen en importancia las explotaciones de ganado ovino-caprino y, en cuanto a las producciones agrícolas, destaca el olivar

Agriculture in a changing climate : Preface

Agriculture is an economic sector that is particularly sensitive to weather. Recent meteorological events have reduced crop production in different parts of the world. Weather extremes resulting from climate change are projected to increase, making crop production more vulnerable and ultimately threatening food security. A continuing effort to develop scientific knowledge in climate and agriculture will help to manage risks and opportunities in these fields. This special issue of Climate Research represents a collection of studies that contribute to the general understanding of weather-related risks and climate impacts on agricultural system

Identification of pore spaces in 3D CT soil images using a PFCM partitional clustering

Recent advances in non-destructive imaging techniques, such as X-ray computed tomography (CT), make it possible to analyse pore space features from the direct visualisation from soil structures. A quantitative characterisation of the three-dimensional solid-pore architecture is important to understand soil mechanics, as they relate to the control of biological, chemical, and physical processes across scales. This analysis technique therefore offers an opportunity to better interpret soil strata, as new and relevant information can be obtained. In this work, we propose an approach to automatically identify the pore structure of a set of 200-2D images that represent slices of an original 3D CT image of a soil sample, which can be accomplished through non-linear enhancement of the pixel grey levels and an image segmentation based on a PFCM (Possibilistic Fuzzy C-Means) algorithm. Once the solids and pore spaces have been identified, the set of 200-2D images is then used to reconstruct an approximation of the soil sample by projecting only the pore spaces. This reconstruction shows the structure of the soil and its pores, which become more bounded, less bounded, or unbounded with changes in depth. If the soil sample image quality is sufficiently favourable in terms of contrast, noise and sharpness, the pore identification is less complicated, and the PFCM clustering algorithm can be used without additional processing; otherwise, images require pre-processing before using this algorithm. Promising results were obtained with four soil samples, the first of which was used to show the algorithm validity and the additional three were used to demonstrate the robustness of our proposal. The methodology we present here can better detect the solid soil and pore spaces on CT images, enabling the generation of better 2D?3D representations of pore structures from segmented 2D images

Real cases study through computer applications for futures Agricultural Engineers

One of the huge concerns on the higher engineer education is the lag of real cases study that the future professionals need in the work and corporation market. This concern was reflected in Bologna higher education system including recommendations in this respect. The knowhow as why this or other methodology is one of the keys to resolve this problem. In the last courses given in Department of Crop Production, at the Agronomy Engineer School of Madrid (Escuela Técnica Superior de Ingenieros Agrónomos, UPM) we have developed more than one hundred applications in Microsoft Excel®. Our aim was to show different real scenarios which the future Agronomic Engineers can be found in their professional life and with items related to crop production field. In order to achieve our target, each application in Excel presents a file text in which is explained the theoretical concepts and the objectives, as well as some resources used from Excel syntax. In this way, the student can understand and use of such application, even they can modify and customize it for a real case presented in their context and/or master project. This electronic monograph gives an answer to the need to manage data in several real scenarios showed in lectures, calculus resolution, information analysis and manage worksheets in a professional and student level