La evaporación del agua del suelo bajo condiciones controladas por la atmósfera, también denominado primera etapa de la evaporación, tiene gran importancia en la Agronomía e Hidrología para aprovechar o predecir el comportamiento del agua en un suelo entre chubascos sucesivos. Sin embargo, no se conoce con precisión cuando termina este periodo. En este trabajo se aprovecha una solución analítica exacta de la ecuación de Richards para caracterizar la duración de esta etapa. Se proponen alternativamente dos modelos sencillos para caracterizar la evaporación durante esta etapa en concordancia con los resultados teóricos más precisos.

The determination of the scheduling and quantity of irrigation is a research activity of great importance because of the intimate relationship between water and production. This relationship varies as a fuction of the climate and crop in question. The purpose of this study was to determine the relationship between the evapotranspiration of different crops and the evaporation of a class A tank as an integrator of climatological characteristics. For each crop under study, an analysis was made of the dependence on the environment, differences between consumption patterns, and the efficiency of evapotranspiration.

The thermogravimetry (TGA) and derivative thermogravimetry (DTG) methods have been used to measure the free water in low-moisture foods. In this study, the 2nd derivative thermogravimetry (2nd DTG) method distinguished the free and bound water based on the speed of moisture evaporation, which could be used for both low-moisture and high-moisture foods. First, the key factors related to moisture evaporation were optimized. Isothermal temperature of 30 ~ 50°C, dynamic temperature of 0.033 ~ 0.133°C/min, and flow rate of nitrogen of 20 ~ 40 mL/min were the optimal parameters for the 2nd DTG method. Under these conditions, the repeatability and reproducibility of the 2nd DTG method were enhanced, its applicability was expanded to high-moisture foods, and the accuracy was ± 4.0% of the nuclear magnetic resonance results. Hence, the 2nd DTG method is better suited for the measurement of free water in foods.

La finalidad del documento es incidir sobre los aspectos de manejo de agua en la producción agrícola bajo riego como una forma de contribuir al entendimiento de los aspectos teóricos y practicos ligados a la producción bajo riego dentro de la complejidad del sistema suelo-agua-planta-atmósfiera y a mejorar la eficiencia de uso del agua de riego.

The determination of the scheduling and quantity of irrigation is a research activity of great importance because of the intimate relationship between water and production. This relationship varies as a fuction of the climate and crop in question. The purpose of this study was to determine the relationship between the evapotranspiration of different crops and the evaporation of a class A tank as an integrator of climatological characteristics. For each crop under study, an analysis was made of the dependence on the environment, differences between consumption patterns, and the efficiency of evapotranspiration.

La evaporacion del agua del suelo bajo condiciones controladas por la atmosfera, tambien denominado primera etapa de la evaporacion, tiene gran importancia en la Agronomia e Hidrologia para aprovechar o predecir el comportamiento del agua en un suelo entre chubascos sucesivos. Sin embargo, no se conoce con precision cuando termina este periodo. En este trabajo se aprovecha una solucion analitica exacta de la ecuacion de Richards para caracterizar la duracion de esta etapa. Se proponen alternativamente dos modelos sencillos para caracterizar la evaporacion durante esta etapa en concordancia con los resultados teoricos mas precisos.