Miguel A. Lugo López falleció en junio de 2005 en Isabela, Puerto Rico. Le sobrevive su esposa la Sra. Aurora de Menkini de Lugo, su hijo Peter, sus nietos y su biznieta. El doctor Lugo López nació el 21 de julio de 1921 en Mayagüez, Puerto Rico, ciudad donde también cursó estudios elementales y superiores. En 1943 se graduó con honores de Bachiller en Ciencias Agrícolas, con una concentración en Agronomía, del Colegio de Agricultura y Artes Mecánicas de la Universidad de Puerto Rico en Mayagüez. Profesionalmente se inició trabajando como Auxiliar de Investigaciones en la Estación Experimental Federal en Mayagüez. Sin embargo, pronto partió hacia la Universidad de Cornell en Ithaca, Nueva York, donde en 1945 obtuvo el grado de Maestro en Ciencias, especializado en Ciencias del Suelo. Allí continuó estudios post-graduados hasta 1946. A su regreso a Puerto Rico sirvió por dos años como Catedrático Auxiliar en el Colegio de Agricultura y Artes Mecánicas de Mayagüez. De allí pasó a ocupar el puesto de Científico Auxiliar de Suelos en la Estación Experimental Agrícola (EEA) de la Universidad de Puerto Rico, en Río Piedras. Posteriormente continuó sus estudios graduados y en 1950 obtuvo el grado de Doctor en Filosofía, en Ciencias del Suelo, en la Universidad de Cornell. Del 1950 al 1957 fue Científico Asociado de Suelos y Director Interino del Departamento de Suelos en la EEA en Río Piedras. Del 1957 al 1960 trabajó en la Subestación de Gurabo como Científico Asociado de Suelos y Científico de Suelos a Cargo; del 1960 al 1961 ocupó el puesto de Director Auxiliar de la EEA a cargo de la Subestación de Gurabo. De la Subestación de Gurabo pasó a la EEA en Río Piedras, donde ocupó los puestos de Director Auxiliar, Director Interino, Director Asociado y Científico de Suelos. Del 1969 al 1972 fue Profesor y Científico de Suelos, además de Director de la Oficina de Programas y Planes y Decano Asociado del Colegio de Ciencias Agrícolas, en el Recinto Universitario de Mayagüez (RUM). Ocupó el puesto de Decano de Estudiantes del RUM del 1972 al 1974. En 1974 regresa a la investigación como Científico de Suelos y Líder del Proyecto de Investigaciones en

En memoria: miguel a. lugo lopez 1921-2005

Physical properties (mechanical behaviour) of a soil greatly influence its use and behaviour towards plant growth. The plant support, root penetration, drainage, aeration, retention of moisture, and plant nutrients are linked with the physical condition of the soil. Physical properties also influence the chemical and biological behaviour of soil. The physical properties of a soil depend on the amount, size, shape, arrangement and mineral composition of its particles. These properties also depend on organic matter content and pore spaces. Important physical properties of soils. 1. Soil texture, 2. Soil structure, 3. Surface area, 4. Soil density, 5. Soil porosity, 6.Soil colour, 7.Soil consistence Soil textureTextural classesParticle size distribution

Soil Physical Properties

Prevailing weather conditions influence herbage growth and quality, and therefore may have a substantial impact on animal production. Before investigating relationships between weather factors, herbage quality and animal production, it is beneficial to first quantify interactions between herbage quality characteristics and mineral concentrations. The objective of the present study was to investigate the association between weather and herbage growth rate, quality and mineral concentration under rotational grazing systems. Daily weather data and weekly records of herbage quality and mineral concentration from a research dairy farm were available across the years 1995 to 2001, inclusive. Herbage growth rates were also recorded on a monthly basis. Results imply moderate correlations between some weather variables and herbage quality and mineral concentration. Generally, the strength of the absolute correlations between weather and herbage-related variables decreased following adjustment of the herbage-related variables for month of year and research farmlet. Negative correlations existed between rainfall and herbage water-soluble carbohydrate (r = –0.19) and organic matter digestibility concentration (r = –0.13) and metabolisable energy content (r = –0.14), independent of time of year and farmlet. Weather explained up to 14% of the variation in herbage nutrient content over and above that explained by time of year and farmlet. Significantly different correlations existed across time between some weather and herbage-related variables, indicating that the relationships may differ across seasons. Results from the present study, in conjunction with information on the effect of herbage quality and/or mineral concentration on animal production, will be valuable in improving our understanding of weather influences on herbage growth, quality and mineral concentration.

Weather, herbage quality and milk production in pastoral systems. 3. Inter-relationships and associations between weather variables and herbage growth rate, quality and mineral concentration

The United Nations Food and Agriculture Organization (FAO) has recommended the Penman-Monteith method as the single method for estimating reference evapotranspiration throughout the world. A disadvantage of the method, however, is its relatively high data requirement. Measurements of wind speed, humidity (or dew point temperature) and radiation tend to be the least available of the required parameters; therefore, the FAO has presented estimation procedures for these parameters. The purpose of this study was to evaluate estimation procedures for climate data to be used in the Penman-Monteith method for estimating long-term daily reference evapotranspiration, and to verify the accuracy of the procedures at four locations in Puerto Rico. Comparison of reference evapotranspiration determined by using the estimated and measured climate data shows reasonably good agreement. The methods presented in this paper are potentially valuable for calculating the long-term average daily reference evapotranspiration at any location in Puerto Rico. An example is provided to illustrate the use of the proposed estimation procedures for climate parameters. This study presents a comparison of reference evapotranspiration calculated by the Penman-Monteith method, with estimates previously made by using the Hargreaves-Samani method, for thirty-four locations in Puerto Rico. In addition, estimated peak evapotranspiration from the Soil Conservation Service (SCS) (now Natural Resources Conservation Service) Irrigation Guide for the Caribbean Area, the SCS Blaney-Criddle method and the Penman-Monteith method were compared for six vegetable crops at three locations in Puerto Rico. The results suggest that some irrigation systems may have been under-designed in terms of flow capacity in Puerto Rico.

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Estimating evapotranspiration in Puerto Rico

Photosynthesis Bibliography volume 1 1966/1970

A brief appraisal of the climatic and related agricultural hydrology aspects of Puerto Rico is discussed In the tropics moisture and latent heat flux cycles are generally more critical than temperature (sensible heat flux) in contrast to these relationships at middle and higher latitudes Yet, a continental-like climate is found in some interior valleys such as at Utuado, where the daily air temperature span is around 22°C in winter A low level inversion (trade-wind inversion) is generally exhibited below 2 km, constituting a most important regulating valve of the general circulation here Frequently, it acts as a strong lid opposing the vertical cloud development necessary to produce rainfall This undesirable situation possibly makes things worse in the drier part of the year, pmducing wide statistical spread from the mean rainfall at that time An appraisal of the Island's hydrology reveals a very unfavorable agricultural water balance for the south coast, in contrast to a decidedly better picture for the north coast Nevertheless, during the past decade both the north and south coasts experienced a build-up of the most extreme drought conditions in the history of the island The Palmer's Drought Index, which coincides with the gap between actual and potential evapotranspiration, shows that 1964, 1965, 1967, and 1968 were the most critical years Application is made of the Crop Moisture Index (CMI) as a more detailed measure of drought in the time scale

On the Climate of Puerto Rico and its Agricultural Water Balance

Yields of 12 local and introduced tanier cultivars, genus Xanthosoma , were compared under irrigated and nonirrigated conditions at the Gurabo Substation. Probably due to a wet and rather short growing season, irrigation did not increase yields significantly. However, under irrigation all cultivars tended to exceed the yield of their counterpart without irrigation. This was particularly evident in Blanca del Pais, Rascana, and Viequera, with average yields increased by 37%.

Yield of Twelve Tanier Cultivars Grown With and Without Irrigation in East-Central Puerto Rico

Soil temperature data at Rio Piedras in the north, Lajas in the southwest, and Fortuna in the south, are given in this paper for the 5-year period 1963- 67. Seasonal variations in soil and air temperatures follow distinct patterns somewhat, depending on the nature of the soil cover and rainfall. Mean maximum and minimum temperatures at the 2-inch depth, respectively, are: Rio Piedras, 96.2° F. and 79.6° F.; Lajas, 102.1° F. and 69.0° F.; and Fortuna, 93.2° F. and 79.1° F. The corresponding soil temperatures at the 8-inch depth, respectively, are: Rio Piedras, 80.5° F. and 77.4° F.; Lajas, 83.4° F. and 77.8° F.; and Fortuna, 85.7° F. and 82.7° F. The differences and trends of soil temperature at 2-inch and 8-inch depths can find adequate explanation when soil moisture and soil cover are considered. However, the differences between maximum and minimum soil temperatures at 8 inches of depth are roughly one fifth of the corresponding ones at the 2-inch depth. The maximum and minimum air temperature at Lajas, Fortuna and Rio Piedras are much more similar to each other than the corresponding soil temperature, especially at the 2-inch depth. This is mainly because air temperature is rather measured on a macro and integrating scale while soil temperature measurements exhibit localized effects of soil cover and soil moisture. It was found that highly significant 2-inch soil-air temperature relationships are evident under bare soil conditions. The same relationships were not significant under sod cover at Fortuna.

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Seasonal Changes in Soil and Air Temperature at Three Locations in Puerto Rico, 1963-67

A laboratory evaluation was directed to provide a means for assessing the need for irrigation based on the simultaneous appraisal of the evaporative demands of the atmosphere and the free energy of water at the soil surface. The method essentially consists in recording the difference in evaporative cooling between a non-ventilated wet bulb thermojunction at the height of a crop canopy and less intensive evaporative cooling at the soil surface, as evaporation proceeds and the free energy of soil water decreases. Utilizing the principle of the thermocouple, a curve is obtained in a microvolt recorder which gets steeper as the evaporative demands increase and the plant gets farther away from the zero time of a given irrigation. Statistical data are presented which indicates that the continuously recorded potential (∆ t ) is a major function of evaporative demands of the air (e d ), of the moisture content of the matrix material (O), and of its evaporation rate (e m ).

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A Psychrometric Approach to Schedule Irrigation

An ecologic study was conducted to evaluate the dry matter yield response and the mean daily growth and water consumption rates of grain sorghum at four climatic sites in the tropics and subtropics. BR-54 seeds of this crop were grown in pots watered by capillarity with a specially-devised fiberglass wick-tin can reservoir technique which permitted water use measurements and drainage through the same wick. Seven weekly harvests were made of shoots and roots separately over a 52-day growth period centered on the March 22 vernal equinox . Climatic sites had a marked effect on dry matter yields (weight of the shoot). The yield response is directly related to the amount of water consumed which, at the same time, is closely related to the leaf area. However, an analysis of variance indicates that the relative growth rate, unit leaf area, water use rate, and other related indices did not significantly differ with climatic sites. As a result, it was found that there existed highly significant quadratic relationships of the relative growth rates and water use rates as a function of days after emergence when the four climatic sites were included together in regression analysis. Linear regression analysis showed also a significant relationship of unit leaf rate and water use rate on the mean daily values of solar radiation intensity and, to a lesser extent, to the open-pan evaporation.

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Modesto Capiel

Papers

On the Climate of Puerto Rico and its Agricultural Water Balance

Yield of Twelve Tanier Cultivars Grown With and Without Irrigation in East-Central Puerto Rico

Seasonal Changes in Soil and Air Temperature at Three Locations in Puerto Rico, 1963-67

A Psychrometric Approach to Schedule Irrigation

An Evaluation of the Growth and Water Consumption Rate of Grain Sorghum (Sorghum bicolor) at Four Climatic Sites in the Tropics and Subtropics