ABSTRACT Laboratory analyses are a fundamental basis for monitoring soil behavior. These analyses are usually tedious and expensive depending on the methodology used, which may limit data acquisition. The aim of this research was to evaluate the potential of Near Infrared (NIR) diffuse reflectance spectroscopy for the estimation of texture and Soil Organic Carbon (SOC) of an Oxisol. A total of 313 samples were collected at fixed depths of 0.0-0.10, 0.10-0.20, 0.20-0.30, 0.30-0.40 and 0.40-0.50 m in 70 points distributed in 248 ha, from which SOC and the fractions of sand, silt and clay were determined. The spectral signatures were obtained from a NIRFlex sensor, and the modeling was done applying partial least squares regression. A highly representative model was obtained for the SOC estimation, with a coefficient of determination (R2) of 0.97, Root Mean Square Error (RMSE) of 1.10 g kg-1 and Residual Prediction Deviation (RPD) of 5.63. For the textural fractions, estimation models of lesser performance were obtained, with R2values of 0.62; 0.44 and 0.62, RMSE values of 1.10%, 2.92% and 3.08%, and RPD values of 1.82, 1.61 and 1.81 for sand, silt and clay, respectively. By means of geostatistical interpolation surfaces, the behavior of the measured and spectrally estimated variables was compared. NIR spectroscopy proved to be a viable alternative for the precise estimation of SOC, while for the textural fractions it is convenient to explore the improvement of the estimates.

RESUMEN Los análisis de laboratorio de suelos son una base fundamental para monitorear su comportamiento. Estos análisis suelen ser tediosos y de costo elevado según la metodología empleada, lo que puede limitar la obtención de esta información. El objetivo de esta investigación fue evaluar el potencial de la espectroscopía de reflectancia difusa deInfrarrojo Cercano (NIR) en la estimación de la textura y el Carbono Orgánico del Suelo (COS) de un Oxisol. Se recolectaronen total 313 muestras a profundidades fijas de 0.0-0.10, 0.10-0.20, 0.20-0.30, 0.30-0.40 y 0.40-0.50 m en 70 puntos distribuidos en 248 ha, y les fueron determinadas el COS, la fracción de arena, limo y arcilla. Con un sensor NIRFlex se obtuvieron las firmas espectrales, y la modelación se efectuó aplicando regresión por mínimos cuadrados parciales. Se obtuvo un modelo de alta representatividad para la estimación del SOC, con coeficiente de determinación (R2) de 0.97, Raíz del Error Cuadrático Medio (RMSE) de 1.10 g kg-1y Desviación Residual de la Predicción (DRP) de 5.63. Para las fracciones texturales se obtuvieron modelos de estimación de menor desempeño, con R2 de 0.62, 0.44 y 0.62, RMSE de 1.10%, 2.92% y 3.08%, y DRP de 1.82, 1.61 y 1.81 para arena, limo y arcilla respectivamente. Por medio de superficies de interpolación geoestadística se comparó el comportamiento de las variables medidas y estimadas espectralmente. La espectroscopía NIR mostró ser una alternativa viable para la estimación precisa del COS, mientras que para las fracciones texturales es conveniente explorar el mejoramiento de las estimaciones.

RESUMEN Con el fin de comparar las pérdidas de suelo en dos sistemas de corte tradicionalmente utilizados en el cultivo de caña de azúcar para la producción de panela, se llevó a cabo un estudio, en el que se realizaron mediciones en campo, utilizando un simulador de lluvia y parcelas de escorrentía, en un vertisol del municipio de Quebradanegra, Cundinamarca, en donde se presentan, simultáneamente, los dos tipos de corte: parejo (tipo de corte en el que se cosecha todo a la vez, al tener una madurez homogénea en el cultivo) y entresaque (sistema en el cual no hay madurez homogénea, por lo que se corta solo un porcentaje de las plantas a la vez). Para estimar las pérdidas de suelo potenciales asociadas a ambos sistemas de corte, se utilizó la Ecuación Universal de Pérdida de Suelos (USLE), obteniendo un factor medio C, asociado al tipo de corte, utilizando los datos determinados en campo y la erosividad de las intensidades de precipitación simuladas. Finalmente, se determinó la erosión potencial anual, bajo los dos sistemas de corte, donde se observó que el sistema de corte por parejo presenta un valor 2,2 veces mayor que el sistema de corte por entresaque. Por otra parte, al comparar las pérdidas potenciales de suelo con un lote recién preparado y sembrado, sin cobertura vegetal, se evidencia la capacidad del cultivo de caña panelera para brindar protección al suelo, presentando una erosión potencial 9 veces menor, en el caso del corte por parejo, con respecto a una condición de suelo sin cobertura vegetal.

ABSTRACT In order to compare soil losses in two cutting systems traditionally used in the cultivation of sugar cane for the production of panela, a study was carried out in which measurements were made in the field using a rainfall simulator and runoff plots in a vertisol of the municipality of Quebradanegra, Cundinamarca, where both types of cut are presented simultaneously: the cut-off system, in which everything is harvested at once having a homogeneous maturity in the crop and the thinning cut system, in which have an inhomogeneous maturity so that only a percentage of the plants is cut at the same time. To estimate the potential soil losses associated with both cutting systems, the Universal Soil Loss Equation (USLE) was used to obtain a mean C factor associated with the type of cut, using the data determined in the field and the erosivity of simulated rainfall intensities. Finally, the anual potential losses of soil was determined under the two cutting systems, where it was observed that the cut-off system has an annual potential erosion 2.2 times greater than the thinning cuy system. On the other hand, when comparing the potential losses of soil with a newly prepared and planted lot, without plant cover, the capacity of the sugarcane cane crop is demonstrated to offer a protection to the soil, presenting a potential erosion 9 times smaller, in the case of the cut-off system, with respect to a soil condition without plant cover.

RESUMO As características físicas do solo são definidas através da interação entre seus atributos, indicando sua qualidade física. A área de estudo está localizada no Centro Agropecuário Marengo, com extensão de 94,5 ha, subdividida em 17 parcelas. O objetivo deste trabalho foi estudar as características capacidade de armazenamento de água, estrutura, consistência e compactação do solo nos dois horizontes superficiais (H1 e H2), para definir as zonas de manejo através do índice de solo. Atributos a resistência do solo à penetração, foi um indicador da degradação com valores superiores a 2 MPa em 13 parcelas. A porosidade total apresentou valores médios ou baixos nos horizontes H1 e H2 com predominância de microporos, o que significa que a capacidade de armazenamento de água apresentou valores inferiores a 14%. Foram identificadas quatro zonas de manejo para cada horizonte, sendo que a primeira zona representa a área onde o solo é capaz de reter entre 17 e 21% de água disponível, com densidade do solo em torno de 1,0 g cm-3 e teor de carbono orgânico próximo de 6%. Em contraste, a quarta zona representa os locais onde os solos são os mais finos, com teor de argila acima de 45%, água disponível inferior a 11% e média de compactação de 4,39 MPa.

ABSTRACT The physical characteristics of the soil are defined through the interaction between its properties, and they, in turn, can indicate its physical quality. The study area is located in the Centro Agropecuário Marengo (Marengo Agricultural Center), with an extension of 94.5 ha, subdivided into 17 plots. The objective of this research was to study characteristics such as water storage capacity, structure, consistency, and soil compaction in the two surface horizons (H1 and H2), in order to define management zones through the soil index. Properties such as soil penetration resistance were an indicator of soil degradation, with values higher than 2 MPa in 13 plots. The total porosity exhibited medium or low values in the H1 and H2 horizons, with a predominance of micropores, which means that the presence of water could be lower than 14%. Four management zones were identified for each horizon, where the first zone represents the area where the soil is capable of retaining between 17% and 21% of the available water, with a bulk density of around 1 g cm-3 and organic carbon content close to 6%. By contrast, the fourth zone represents the sites where the soils are the finest, with contents above 45% clay, available water less than 11%, and a mean compaction of 4.39 MPa.

ABSTRACT Weather conditions influence the quality parameters of pineapple guava fruit during growth and development. The aim of this study was to propose a model of pre-harvest fruit quality as a function of weather conditions in the cultivation area. Twenty trees were flagged per farm in 2 localities of the Department of Cundinamarca, Colombia: Tenjo (2,580 m.a.s.l.; 12.5 °C; relative humidity between 74 and 86%; mean annual precipitation 765 mm) and San Francisco de Sales (1,800 m.a.s.l.; 20.6 °C; relative humidity between 63 and 97%; mean annual precipitation 1,493 mm). Measurements were performed every 7 days during 2 harvest periods starting on days 96 (Tenjo) and 99 (San Francisco de Sales) after anthesis and until harvest. The models were obtained using Excel® Solver, and a set of data was obtained for the 2 different cultivar periods and each study site. The results showed that altitude, growing degree days, and accumulated precipitation are the weather variables with the highest influence on the physicochemical characteristics of the fruit during growth. The models of fresh weight, total titratable acidity, and skin firmness better predict the development of fruit quality during growth and development. Equations were obtained for increases of length and diameter as a function of fruit weight and for days from anthesis as a function of growing degree days and altitude. The regression analysis parameters showed that the models adequately predicted the fruit characteristics during growth for both localities, and a cross-validation analysis showed a good statistical fit between the estimated and observed values.

ABSTRACT Knowledge of agricultural soils is a relevant factor for the sustainable development of farming activities. Studies on agricultural soils usually begin with the analysis of data obtained from sampling a finite number of sites in a particular region of interest. The variables measured at each site can be scalar (chemical properties) or functional (infiltration water or penetration resistance). The use of functional geostatistics (FG) allows to perform spatial curve interpolation to generate prediction curves (instead of single variables) at sites that lack information. This study analyzed soil penetration resistance (PR) data measured between 0 and 35 cm depth at 75 sites within a 37 ha plot dedicated to livestock. The data from each site were converted to curves using non-parametric smoothing techniques. In this study, a B-splines basis of 18 functions was used to estimate PR curves for each of the 75 sites. The applicability of FG as a spatial prediction tool for PR curves was then evaluated using cross-validation, and the results were compared with classical spatial prediction methods (univariate geostatistics) that are generally used for studying this type of information. We concluded that FG is a reliable tool for analyzing PR because a high correlation was obtained between the observed and predicted curves (R2 = 94 %). In addition, the results from descriptive analyses calculated from field data and FG models were similar for the observed and predicted values.

La importancia ambiental y económica del uso racional de insumos para una agricultura competitiva y sostenible hace necesaria una mayor comprensión de las diferentes variables que intervienen en la producción agrícola. El objetivo del presente estudio fue establecer el comportamiento espacial de los atributos químicos del suelo y su relación con el rendimiento y la calidad del café en un Typic Hapludands. El muestreo se realizó de manera aleatoria en 64 puntos georreferenciados a una profundidad de -0,20 m. Los datos fueron analizados a través de estadística descriptiva, geo-estadística, correlaciones lineales y los métodos multivariados clúster y componentes principales (ACP). La interpolación se realizó a través de kriging. El análisis descriptivo mostró alta variabilidad para los atributos químicos y los demás mostraron dependencia espacial excepto el contenido de B en el suelo. Se presentó una correlación de 35,88 % entre el contenido de carbono orgánico del suelo (CO) y el rendimiento, además de una correlación negativa de 40,98 % entre la merma en trilla y el contenido de Ca en el suelo. El análisis de componentes principales (ACP) y clúster mostraron poca relevancia para los atributos Na, P, B y rendimiento. A partir del análisis clúster y la distribución espacial, se propone un manejo para el cultivo de café.

Given the environmental and economic importance of the rational use of inputs for a competitive and sustainable agriculture, a greater understanding of the different variables involved in agricultural production is required. Therefore, the aim of this study was to establish the spatial behavior of the chemical properties of the soil and their relationship with coffee yield and quality on Typic Hapludands. Sampling was done randomly in 64 georeferenced points to a depth of -0.20. Data were analyzed using descriptive and geostatistics statistics, linear correlations and multivariate methods cluster and principal components (PCA); additionally, the interpolation of data was conducted using the kriging method. The descriptive analysis showed high variability for chemical attributes, in terms of geostatistics, the results showed spatial dependence for all attributes except for the content of B in the soil. There was a 35.88 % correlation between the soil attributes (SOC content) and the attributes of the crop (yield). Besides, an inverse relationship of 40.98 % between the reduction in threshing (decrease) and the Ca content in soil was observed. Both principal analysis (PCA) components and cluster analysis showed less relevance to the analysis on the attributes Na, P, B and yield. From cluster analysis and spatial distribution, management of coffee growing is proposed.

A importância ambiental e econômica do uso racional de insumos para una agricultura competitiva e sustentável faz necessária una maior compreensão das diferentes variáveis que intervêm na produção agrícola. O objetivo do presente estudo foi estabelecer o comportamento espacial dos atributos químicos do solo e a sua relação com o rendimento e a qualidade do café em um Typic Hapludands. A amostragem se realizou de maneira aleatória em 64 pontos georreferenciados a una profundidade de -0,20 m. Os dados foram analisados através de estatística descritiva, geoestatística, correlações lineares e os métodos multivariados clúster e componentes principais (ACP). A interpolação realizou-se através de kriging. A análise descritiva mostrou alta variabilidade para os atributos químicos e os demais mostraram dependência espacial exceto o conteúdo de B no solo. Apresentou-se una correlação de 35,88 % entre o conteúdo de carbono orgânico do solo (CO) e o rendimento, além do mais de una correlação negativa de 40,98 % entre a diminuição em trilha e o conteúdo de Ca no solo. A análise de componentes principais (ACP) e clúster mostraram pouca relevância para os atributos Na, P, B e rendimento. A partir da análise clúster e a distribuição espacial, propõe-se um manejo para a cultura de café.

Fruit growth is stimulated by different weather conditions. The aim of this study was to determine the influence of weather conditions on the physicochemical properties of pineapple guava fruit growth. Twenty trees were marked in two production areas located at different altitudes (1,800 and 2,580 m.a.s.l.), and measurements were performed every 7 days from 99 and 141 days post-anthesis to harvest at altitudes of 1,800 and 2,580 m.a.s.l., respectively. The results indicate that altitude and weather conditions greatly influence the growth and development of pineapple guava fruit, and these effects are primarily manifested in the physical characteristics of the fruit. The weight and size of the fruit at harvest are directly related to the altitude of the production area. The weather condition that has the greatest impact on total titratable acidity at harvest is cumulative radiation during fruit growth; the highest value of total soluble solids at harvest corresponds to the location with the higher altitude, lower rainfall and relative humidity and higher cumulative radiation during the fruit growth period. The hue angle and pulp firmness at harvest are not influenced by the location or weather conditions at any location and do not determine the fruit quality at harvest time.

Desde el año 2010 y hasta el 2012 se realizó la evaluación de 23 tipos de emisores o goteros que se encuentran en el mercado colombiano y se les determinó: el coeficiente de variación (CV); la variación del caudal medio comparado con el caudal nominal; las dimensiones de los pasajes y de sus partes constitutivas; la sensibilidad a la presión; el tipo de material y la resistencia a la presión hidrostática. Las mediciones se realizaron en el laboratorio de riego a presión del Departamento de Ingeniería Civil e Ingeniería Agrícola de la Facultad de Ingeniería de la Universidad Nacional de Colombia, Bogotá, en condiciones de operación controladas de acuerdo con las normas de calidad ISO 9260, 1991 y UNE 68-075, 1986. De los emisores evaluados el 43,48% son categoría A, con CV menor a 5%, el 26,09% categoría B con CV entre 5% y 10% y el 30,43% categoría C, con CV mayor a 10%. El porcentaje de variación del caudal medio respecto al caudal nominal de los emisores analizados muestran que solo el 17,32% (4) corresponden a la categoría A, mientras que el 82,61% (19) restante a la categoría B. Cinco emisores tienen una altura de laberinto menor a 0,7 mm, diecisiete entre 0,7 y 1,5 mm y uno superior a 1,5 mm (que los hace: muy sensible, ligeramente sensible y muy resistente a taponamiento, respectivamente). Este trabajo muestra la importancia de las características del emisor en las instalaciones de riego y la incidencia sobre el ahorro de agua, consumo de energía y combustible y el incremento de la rentabilidad al reducir los costos de operación y aumentar la eficiencia de distribución del agua.

From 2010 to 2012, an assessment was carried out on twenty-three emitter or dripper types found in the Colombian market. The following were determined: the coefficient of variation (CV), the variation of the average flow rate compared to the nominal flow, the dimensions of the passages and the constituent parts, the pressure sensitivity, the type of material and the resistance to hydrostatic pressure. The measurements were taken in the laboratory of pressurized irrigation, Department of Civil Engineering and Agricultural Engineering, Faculty of Engineering, National University of Colombia, Bogotá with controlled operating conditions, according to the quality standards of ISO 9260, 1991 and UNE 68-075, 1986. Of the evaluated emitters, 43.48% were category A, with a CV less than 5%, 26.09% were category B, with a CV between 5 and 10%, and 30.43% were category C, with a CV greater than 10%. The percentage change in average flow rate with respect to the nominal flow of the evaluated emitters showed that only 17.32% (4) were category A, while 82.61% (19) were Class B. Five drippers had a labyrinth height lower than 0.7 mm, 17 between 0.7 and 1.5 mm and one above 1.5 mm (which correlate to very sensitive, slightly sensitive and highly resistant to clogging, respectively). This study shows the importance of emitters in irrigation facilities and the impact on water conservation, energy and fuel consumption and increased profitability from reducing operating costs and increasing the efficiency of water distribution.

El maracuyá presenta un incremento significativo en producción y consumo en Colombia en los últimos años. Las pérdidas poscosecha hacen conveniente la introducción de tecnologías que permitan su aprovechamiento más eficiente. El objetivo del presente trabajo fue caracterizar la pulpa de maracuyá (Passiflora edulis f. flavicarpa) y determinar las variables de secado adecuadas para la obtención de pulpas deshidratadas en lámina. Se dimensionó y construyó un equipo para pruebas de secado estático y se caracterizó la pulpa de maracuyá (contenido de humedad, sólidos solubles, pH y acidez). Se obtuvieron las curvas de secado con aire forzado para diferentes condiciones de temperatura (50, 55, 60 y 65°C) y velocidad del aire (178,3; 206,1 y 231,4 m min-1), encontrándose que una temperatura del aire de secado de 65°C y una velocidad del aire de 231,4 m min-1 son las condiciones más adecuadas para la deshidratación de las pulpas de maracuyá utilizadas en la fase experimental. Los productos deshidratados fueron evaluados por el panel de jueces, con buena aceptación por parte de los panelistas; esta evaluación sirvió como base para la determinación de las condiciones más adecuadas para la deshidratación desde el punto de vista sensorial. El comportamiento de los productos obtenidos con relación a sus parámetros de conservación fue satisfactorio; los recuentos microbiológicos estuvieron dentro de los rangos aceptables para productos deshidratados, lo que fue favorecido por la reducida actividad de agua alcanzada en el producto deshidratado.

The yellow passion fruit has seen a significant increase in production and consumption in Colombia in recent years. Postharvest losses have led to the introduction of technologies to increase efficiency. The aim of this study was to characterize passion fruit (Passiflora edulis f. flavicarpa) pulp and determine the appropriate drying variables to obtain dehydrated pulp sheets. A device was designed and built for static drying testing, and passion fruit pulps were characterized (moisture content, soluble solids, pH and acidity). Curves for forced air drying at different temperatures (50, 55, 60 and 65°C) and for air velocity (178.3, 206.1 and 231,4 m min-1) were obtained, with a finding that a drying air temperature of 65°C and an air velocity of 231.4 m min-1 are the most suitable conditions for the dehydration of the banana and passion fruit pulps used in the experimental phase. Dehydrated products were evaluated by a panel of judges, with good acceptance by the panelists; this assessment served as a basis for determining the most suitable conditions for dehydration from the sensory point of view. The behavior of the products obtained in connection with their preservation parameters was satisfactory; microbiological counts were within acceptable ranges for dehydrated products, which were favored by the low water activity achieved in the dehydrated products.

El objetivo del presente estudio fue evaluar el efecto de la utilización del sistema de doble línea de riego versus el tradicional de una línea por hilera de plantas en la producción y calidad de la pera (Pyrus communis) variedad Triunfo de Viena. La investigación se basó en la aplicación de dos tratamientos definidos, uno consistente en una línea de goteo por hilera de plantas con seis emisores de 8 lt/h y otro, con dos líneas de goteo por hilera de plantas con tres emisores de 8 lt/h cada uno Se utilizaron sensores Watermark para medir y controlar el potencial matricial del suelo. Se cubrió el 100% de la evapotranspiración potencial que fue de 55.5 mm/mes. Los resultados obtenidos de las variables hídricas del suelo permitieron programar el riego y garantizar el suministro de agua adecuado en el periodo de déficit hídrico. El tratamiento de doble línea no difirió significativamente del control, lo que indica que utilizar una línea de riego permite obtener una producción y calidad similares con un menor costo inicial del equipo.

The rational use of water becomes every day ever more important in fruit production. The aim of this study was to evaluate the effect of the use of double drip line from a line by line plant in pear (Pyrus communis) production, cv. Triunfo de Viena. The research was based on the application of two specific processes, one consisting of a drip line per row of plants with six emitters of 8 lt h-1 and another with two drip lines per row of plants with three emitters of 8 lt h-1 each. Watermark sensors were used to measure and control the soil matric potential. It covered 100% of potential evapotranspiration, which amounted to 55.5 mm month-1. The results of the variables permitted ground water irrigation scheduling and ensure adequate water supply during the period of water deficit. The double-line treatment did not differ significantly from the control in terms of production and fruit quality, which indicates that to use only one drip line will permit to get a similar yield and quality at a lower initial equipment cost.

Soil variability occurs due to natural and anthropogenic factors acting at various spatial and temporal scales. The purpose of this study was to evaluate the spatial variability as well as the relation of some chemical attributes using different statistical techniques. The study was conducted in the municipality of Maracanaú (CE, Brazil) in the commercial area of sugar cane in a typic Hapludalf. Soils were sampled in a 100 x 100 m grid every 10 m and at a depth between 0 and 20 cm for determination of exchangeable acidity, pH (KCl), Ca, Na, K, Mg, P, N, sum of bases, cationic exchange capacity, base saturation and organic matter. Data were subjected to analysis of descriptive statistics, multivariate analysis and geostatistics. Attributes showed low and medium variability, except for pH that did not show spatial dependence. Different statistical tools helped to identify the soil spatial variability and to get a better understanding of relationships among different attributes. Techniques also allowed to better plan and control agricultural production, especially in carrying out site specific management of agricultural inputs.

La variabilidad del suelo ocurre debido a factores que actúan en varias escalas espaciales y temporales, naturales o antrópicas. El objetivo del presente estudio fue evaluar la variabilidad espacial y la relación de algunos atributos químicos, mediante diferentes técnicas estadísticas. El trabajo fue realizado en el municipio de Maracanaú (CE, Brasil), en área comercial de caña de azúcar, en un Typic Hapludalfs. Se tomaron muestras de suelo cada 10 m, en una malla regular de 100 m x 100 m, en una capa entre 0 y 0,20 m, para la determinación de acidez intercambiable, pH (KCl), Ca, Na, K, Mg, P, N, suma de bases, capacidad de intercambio catiónica, saturación de bases y materia orgánica. Los datos fueron analizados mediante estadística descriptiva, multivariada y, geoestadística e interpolación por kriging ordinario. Los atributos presentaron variabilidad baja o media, donde el pH fue el único atributo que no presentó dependencia espacial. Las diferentes técnicas estadísticas ayudaron a caracterizar la variabilidad espacial del suelo y la identificación de las diferentes relaciones entre atributos, cuyos resultados permiten una mejor planeación y control en la producción agrícola, especialmente en la realización de prácticas de manejo localizado de insumos agrícolas.

El estudio de las técnicas de infiltración de agua en el suelo permite entender los procesos hidrológicos, la degradación de suelos y el transporte de solutos, siendo un soporte significativo, para minimizar los métodos de escorrentía superficial. El objetivo del presente trabajo fue evaluar el comportamiento de la infiltración, a través de los modelos de Kostiakov, Kostiakov- Lewis y Philip. El trabajo fue realizado en el municipio de Puerto López (Meta-Colombia). La metodología incluyó la ejecución de 64 pruebas de infiltración, usando anillos infiltrómetros dobles, en una malla rectangular de muestreo de 52mx45m. En cada punto de la malla, se tomaron muestras de suelo, a 10cm de profundidad, para determinar textura, humedad volumétrica y densidad aparente. Con las curvas de infiltración experimental, se realizaron ajustes a los modelos empíricos para cada punto. Para el análisis de datos, se implementó la estadística descriptiva, con el fin de conocer el comportamiento y la dispersión de las propiedades del suelo. De la misma manera, se establecieron las correlaciones entre las propiedades del suelo y los parámetros de cada modelo. Los datos experimentales tuvieron un mejor ajuste al modelo de Kostiakov-Lewis, seguido del modelo de Kostiakov, con un R² de 0,99 y 0,98, respectivamente. La propiedad que mayor incidencia presentó en la infiltración fue la densidad aparente, observándose una correlación inversa con la mayoría de los parámetros de los modelos. La variabilidad de la infiltración indica la conveniencia de identificar zonas de manejo, para evitar déficit o excesos de agua, que pueden someter el cultivo a estrés hídrico o favorecer procesos de escorrentía superficial.

The study of water infiltration processes into the soil helps to understand hydrological processes, soil degradation and solutes transport, with significant support to minimize runoff processes. The aim of this study was to evaluate the infiltration behaviour through Kostiakov, Kostiakov-Lewis and Philip models. This research was carried out at the Puerto López municipality (Meta-Colombia). The methodology included the implementation of 64 infiltration tests, using double ring infiltrometer, located in a rectangular grid sampling of 52m by 45m. At each grid point soil samples were taken at 10cm depth, to determine texture, bulk density and volumetric moisture. With the experimental infiltration curves adjustments were made to the empirical models for each point. For data analysis descriptive statistics were implemented in order to understand the behaviour and dispersion of soil properties. Correlations between soil properties and parameters of the estimated models were also established. The experimental data were better fit the Kostiakov-Lewis model, following the model of Kostiakov, with an R² of 0.99 and 0.98, respectively. The property of higher incidence over the infiltration was the bulk density, showing an inverse correlation with most of the parameters. The infiltration variability indicates the desirability of identifying management zones, to avoid a deficit or excess water, which can carry the crop to water stress or contribute to runoff processes.

El desarrollo y la aplicación de tecnologías para establecer el comportamiento espacial de los suelos permite optimizar el uso de los diferentes recursos agrícolas, con el fin de mejorar la sostenibilidad y la competitividad, reduciendo el riesgo de degradación ambiental y mejorando su rentabilidad. El objetivo del presente estudio fue evaluar la variabilidad espacial y la relación de algunas propiedades químicas del suelo, mediante diferentes técnicas estadísticas. El trabajo fue realizado en el municipio de Pasca (Cundinamarca), en área productora de Cyphomandra betacea (Cav.) Sendtn., en un Entisol. Se tomaron 64 muestras en una malla regular, con distancias perpendiculares entre puntos de 25 x 12,5m, a una profundidad de 0,20m, determinando carbono orgánico, pH, Ca, Mg, K, suma de bases y la relación Ca:Mg. Los datos fueron analizados mediante estadística descriptiva, análisis multivariado, geoestadística e interpolación por kriging. Los atributos manifestaron variabilidad baja o media, donde el K fue el único atributo que no presentó dependencia espacial. Se observó una fuerte relación entre los cationes, así como una estrecha relación entre el Ca y la suma de bases. Los mapas de contorno confirmaron la variabilidad espacial de las propiedades, lo que indica la conveniencia de la aplicación de insumos agrícolas mediante tasa variada. Con la adaptación de esta metodología, se puede mejorar el diseño experimental de futuras investigaciones, además de ser la base para el establecimiento de cultivos, bajo la concepción de agricultura de precisión.

Development and application of technologies for establishing the spatial behavior of soils, allow to optimize the use of different agricultural resources in order to improve the sustainability and competitiveness, reducing the risk of environmental degradation and improving its profitability. The aim of this study was to evaluate the spatial variability and the relationships of some soil chemical properties, using different statistical techniques. The reseach was carried out in the municipality of Pasca (Cundinamarca) in a Cyphomandra betacea (Cav.) Sendtn. production area, in an Entisol. On a regular grid, 64 samples were taken, with perpendicular distances between points 25 x 12.5m, at 0.20m of depth, evaluating organic carbon, pH, Ca, Mg, K, sum of bases and Ca:Mg relation. The data were analyzed using descriptive statistics, multivariate analysis, geostatistics and interpolation by kriging. The attributes showed low to medium variability, where the K was the only attribute that showed no spatial dependence. There was a strong relationship between cations, and a close relationship between Ca and the sum of bases. The contour maps confirmed the spatial variability of the properties, indicating the appropriateness of the agricultural inputs application at a variable rate. By adapting this methodology it is possible to improve the experimental design of future research, besides being the basis for the establishment of crops under precision agriculture concepts.

A agricultura convencional utiliza o solo intensivamente, modificando os seus atributos. Neste estudo, objetivou-se avaliar a variabilidade espacial de alguns atributos físicos e carbono orgânico do solo em um Argissolo Vermelho-Amarelo cultivado com cana-de-açúcar, usando geoestatística. O trabalho foi realizado em Maracanaú - CE, em uma área de produção de cana-de-açúcar, manejado mediante preparo conservacionista sobre uma cobertura de palhada de cana-de-açúcar. As amostras de solo foram retiradas de uma profundidade de 0,00 - 0,20 m, em uma malha, com intervalo regular de 10 m, totalizando 100 pontos. Em cada amostra, foi analisado densidade de partículas, densidade do solo, carbono orgânico, porosidade total, macroposidade e microposidade. O coeficiente de variação indicou variabilidade baixa para densidade de partículas, densidade do solo e porosidade total e média para as variáveis macroporosidade, microporosidade e carbono orgânico. As variáveis analisadas mostraram dependência espacial, a qual foi observada nos mapas de krigagem. A distribuição de poros por tamanho e a porosidade total indicam condições físicas razoavelmente boas, embora com valores de densidade do solo ligeiramente acima do nível considerado adequado para a classe textural do solo.

Conventional farming uses the soil intensively, modifying its attributes. The goal of this study is to evaluate the spatial variability of some physical attributes and soil organic carbon in red-yellow Anfissol cultivated with sugar cane, using geostatistics. The work was carried out at Maracanaú - CE, in area with sugar cane production, managed by conservation tillage practices five years ago, which remained covered with sugarcane straw mulch. Soil samples were taken from 0.00 to 0.20 m de pth, in a mesh, with a regular interval of 10 m, totaling 100 points. For each sample, soil particle density, bulk density, organic carbon, porosity, macro pores, and micro pores were analyzed. The coefficient of variation indicated low variability for soil particles density, bulk density, total and average porosity for the variables of macro- and microporosiy, and organic carbon. The variables analyzed showed spatial dependence, which was observed in kriging maps. The pores distribution by size and total porosity indicate adequate physical conditions, with bulk density values slightly above the level considered suitable for this textural class of soil.

La ciruela variedad Horvin es una fruta altamente perecedera, lo cual dificulta el manejo poscosecha, además porque actualmente en Colombia no se dispone de una red de frío ni de una infraestructura adecuada para el manejo poscosecha. El objetivo del presente trabajo fue el de evaluar la calidad de la ciruela variedad Horvin bajo tres condiciones de almacenamiento refrigerado. La ciruela variedad Horvin es un fruto climatérico, donde la intensidad respiratoria está influenciada por las condiciones de almacenamiento, presentando una relación directa con la temperatura, encontrándose que el almacenamiento a 4º C es la más favorable para mantener la calidad de la ciruela, con una pérdida de peso acumulada del 13,23%, valores de firmeza superiores a 20 N y sólidos solubles totales (SST) superiores a 11º Brix, al finalizar el periodo de almacenamiento a los 31 días. La pérdida de peso, la intensidad respiratoria, la firmeza, la acidez titulable (AT) y la relación SST/AT, son los parámetros que mejor representan la evolución de la madurez de la ciruela variedad Horvin durante el almacenamiento. Los sólidos solubles totales no presentaron alta variabilidad en las diferentes condiciones de almacenamiento evaluadas, parámetro que no debe considerarse como índice de madurez durante el periodo poscosecha.

The plum cv. Horvin is a highly perishable fruit, this makes difficult the postharvest handling, in addition actually in Colombia there is no cold storage chamber and neither adequate handling postharvest infrastructure. The objective of the present work was to evaluate the quality of the plum cv. Horvin, under three storage conditions. The plum cv. Horvin is a climacterical fruit, where the respiratory rate is influenced by the storage conditions, showing a direct relation with the temperature, finding the storage to 4ºC is the best condition to keep the quality of the plum cv. Horvin, with an accumulated weight loss of 13.23%, firmness upper 20 N and total soluble solids (SST) upper 11ºBrix, when the storage period finish to 31 days. The weight loss, the respiratory rate, the firmness, the titratable acidity (AT) and the SST/AT relation, are the parameters that better represent the maturity evolution of the plum cv. Horvin during storage. Total soluble solids did not show high variability in the storage conditions analyzed, parameter that does not have to consider like maturity index during postharvest.