Problems in the use of microplots for assessing the fate of urea applied to flooded rice

1988 ◽  
Vol 39 (3) ◽  
pp. 351 ◽  
Author(s):  
ACF Trevitt ◽  
JR Freney ◽  
JR Simpson ◽  
WA Muirhead
Keyword(s):  
Solar Radiation ◽  
Preliminary Analysis ◽  
Ammonia Volatilization ◽  
Urea Hydrolysis ◽  
Incident Solar Radiation ◽  
Size And Shape ◽  
Flooded Rice ◽  
Ph Values ◽  
Plot Size ◽  
Heat Penetration

The effects of differences in size of microplot and type of enclosure on the floodwater parameters determining ammonia volatilization were studied. The results show that the use of enclosures can retard urea hydrolysis, suppress the maximum daytime pH values (an effect which is cumulative over a number of days), and significantly reduce the potential for ammonia volatilization. These effects are the consequence of lowered light (and heat) penetration in the enclosed area due to shading of the floodwater by the enclosure walls. The magnitude of these effects varies with plot size and shape, and the material used for construction of the plot wall. A preliminary analysis suggests that, if errors due to shading are acceptable when 90% or more of the incident solar radiation always penetrates to the enclosed floodwater, then square plots with opaque walls must be at least 1.2 m along a side and cylindrical plots must be at least 1.2 m in diameter when wall height is 0.1 m above the floodwater.

Field Plot Technique Studies with Flue‐Cured Tobacco. I. Optimum Plot Size and Shape 1

1963 ◽  
Vol 55 (2) ◽  
pp. 197-199 ◽  
Author(s):  
Julian W. Crews ◽  
Guy L. Jones ◽  
D. D. Mason
Keyword(s):  
Field Plot ◽  
Size And Shape ◽  
Plot Size ◽  
Field Plot Technique

scholarly journals Utilising Open Geospatial Data to Refine Weather Variables for Building Energy Performance Evaluation—Incident Solar Radiation and Wind-Driven Infiltration Modelling

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 802
Author(s):  
Kristian Skeie ◽  
Arild Gustavsen
Keyword(s):  
Solar Radiation ◽  
Web Service ◽  
Meteorological Data ◽  
Surface Wind ◽  
Building Energy ◽  
Energy Performance ◽  
Geospatial Data ◽  
Weather Data ◽  
Building Site ◽  
Incident Solar Radiation

In building thermal energy characterisation, the relevance of proper modelling of the effects caused by solar radiation, temperature and wind is seen as a critical factor. Open geospatial datasets are growing in diversity, easing access to meteorological data and other relevant information that can be used for building energy modelling. However, the application of geospatial techniques combining multiple open datasets is not yet common in the often scripted workflows of data-driven building thermal performance characterisation. We present a method for processing time-series from climate reanalysis and satellite-derived solar irradiance services, by implementing land-use, and elevation raster maps served in an elevation profile web-service. The article describes a methodology to: (1) adapt gridded weather data to four case-building sites in Europe; (2) calculate the incident solar radiation on the building facades; (3) estimate wind and temperature-dependent infiltration using a single-zone infiltration model and (4) including separating and evaluating the sheltering effect of buildings and trees in the vicinity, based on building footprints. Calculations of solar radiation, surface wind and air infiltration potential are done using validated models published in the scientific literature. We found that using scripting tools to automate geoprocessing tasks is widespread, and implementing such techniques in conjunction with an elevation profile web service made it possible to utilise information from open geospatial data surrounding a building site effectively. We expect that the modelling approach could be further improved, including diffuse-shading methods and evaluating other wind shelter methods for urban settings.

Rotifer dynamics in three shallow lakes from the Salado river watershed (Argentina): the potential modulating role of incident solar radiation

2015 ◽  
Vol 14 (11) ◽  
pp. 2007-2013 ◽  
Author(s):  
Nadia Diovisalvi ◽  
Armando M. Rennella ◽  
Horacio E. Zagarese
Keyword(s):  
Solar Radiation ◽  
Shallow Lakes ◽  
Seasonal Cycle ◽  
Schematic Representation ◽  
Incident Solar Radiation ◽  
River Watershed ◽  
Clear Sky ◽  
Rotifer Species ◽  
Salado River

A schematic representation of the seasonal cycle of rotifer in L. Chascomús. In this figure the relative abundances of the three dominant rotifer species are expressed as fractions of the estimated clear-sky mean daily incident solar radiation.

scholarly journals Assessment of Heat Stress and Cloudiness Probabilities in Post-Flowering of Wheat and Canola in The Southern Cone of South America

2021 ◽  
Author(s):  
Gonzalo Martín Rivelli ◽  
María Elena Fernández Long ◽  
Leonor Gabriela Abeledo ◽  
Daniel Calderini ◽  
Daniel Julio Miralles ◽  
...  
Keyword(s):  
Heat Stress ◽  
Solar Radiation ◽  
South America ◽  
Southern Cone ◽  
Maximum Temperature ◽  
Curvilinear Relationship ◽  
Climate Scenarios ◽  
Incident Solar Radiation ◽  
Probability Of Occurrence ◽  
Combined Stresses

Abstract Episodes of heat stress constrain crop production and will be aggravated in the near future according to short and medium-term climate scenarios. Global increase in cloudiness has also been observed, decreasing the incident solar radiation. This work was aimed to quantify the probability of occurrence of heat stress and cloudiness, alone or combined, during the typical post-flowering period of wheat and canola in the Southern Cone of South America. Extended climate series (last 3-5 decades with daily register) of 33 conventional weather stations from Argentina, Brazil, Chile and Uruguay (23ºS to 40ºS) were analysed considering the period from September to December. Two different daily events of heat stress were determined: i) maximum daily temperature above 30ºC (T>30ºC), and ii) 5ºC above the historical average maximum temperature of that day (T+5ºC). A cloudiness event was defined in our work as incident solar radiation 50% lower than the historical average radiation of that day (R50%). The T>30ºC event increased its probability of occurrence throughout the post-flowering phase, from September to December. By contrast, the risk of T+5ºC event decreased slightly, just like for R50%, and the higher the latitude, the lower the probability of R50%. The T>30ºC plus R50% combined stresses reached greater cumulated probabilities during post-flowering, compared to T+5ºC plus R50%, being 42% vs. 15% in northernmost locations, 26% vs. 19% in central (between 31ºS to 35ºS), and 28% vs. 1% in southernmost locations, respectively. A curvilinear relationship emerged between the monthly probability of combined stresses and the number of days with stress per month. In summary, T>30ºC was the most frequent thermal stress during post-flowering in wheat and canola. Both combined stresses had a noticeable risk of occurrence, but T>30ºC plus R50% was the highest. Evidence of the recent past and current occurrence of heat stress individually, and its combination with cloudiness events during post-flowering of temperate crops, serves as a baseline for future climate scenarios in main cropped areas in the Southern Cone of South America.

scholarly journals Radiación fotosintéticamente activa evaluada en la ciudad de Zacatecas

2020 ◽  
pp. 1-11
Author(s):  
Mónica Montserrat Escobedo-Sánchez ◽  
Ricardo Conejo-Flores ◽  
Sergio Miguel Durón-Torres ◽  
Juan Manuel García-González
Keyword(s):  
Decision Making ◽  
Solar Radiation ◽  
Production Planning ◽  
Photosynthetically Active Radiation ◽  
Detailed Knowledge ◽  
Active Radiation ◽  
Incident Solar Radiation ◽  
Daily Average ◽  
Life On Earth

The present investigation is related to one of the most important processes for the development of life on Earth; photosynthesis, an essential process in the cycle and development of living beings, centered on solar radiation that is useful for plants to carry out this process, Photosynthetically Active Radiation (PAR). The objective of this work is to generate information on the PAR through a database to collaborate in the decision-making of farmers in the area. For this purpose, a quantum sensor installed in building 6 of the UAZ Siglo XXI Campus was used. According to Abal (2013), in agricultural and production planning, it is especially important to have a detailed knowledge of incident solar radiation on the earth's surface (Abal and Durañona, 2013). When collecting, treating and analyzing the data, it was found that the daily average PAR is 819.52 μmol of photons m-2 s-1 (179.47 W m-2), if only the sunny hours are taken into account. It can be concluded that according to the PAR received in the evaluation region and the type of nutrients in the soil, other crop alternatives to those traditionally used can be sought.

scholarly journals Using Soil Water to Control Ammonia Emission from Acid Soils with and Without Chicken Litter Biochar

2019 ◽  
Vol 8 (3) ◽  
pp. 23
Author(s):  
Maru Ali ◽  
Ahmed Osumanu Haruna ◽  
Nik Muhamad Abd Majid ◽  
Walter Charles Primus ◽  
Nathaniel Maikol ◽  
...  
Keyword(s):  
Soil Water ◽  
Ammonia Volatilization ◽  
Chemical Properties ◽  
Field Capacity ◽  
Urea Hydrolysis ◽  
Water Levels ◽  
Soil Chemical Properties ◽  
Ammonia Emission ◽  
Ammonia Loss ◽  
Chicken Litter

Although urea use in agriculture is on the increase, increase in pH at soil microsite due to urea hydrolysis which causes ammonia emission can reduce N use efficiency. Among the interventions used to mitigate ammonia loss include urease inhibitors, clinoptilolite zeolite, coated urea, and biochar but with little attention to the use of soil water levels to control ammonia volatilization. The objective of this study was to determine the effects of soil water levels on ammonia volatilization from soils with and without chicken litter biochar. Dry soils with and without chicken litter biochar were subjected to 0%, 25% 50%, 75%, 100%, and 125% soil water. There was no urea hydrolysis in the soil without water. Chicken litter biochar as soil amendment effectively mitigated ammonia loss at 1% to 32% and 80% to 115% field capacity. However, urea used on soil only showed lower ammonia loss at 33% to 79% and 116% to 125% field capacity compared with the soils with chicken litter biochar. At 50% field capacity ammonia loss was high in soils with and without chicken litter biochar. Although chicken litter biochar is reputed for improving soil chemical properties, water levels in this present study affected soil chemical properties differently. Fifty percent field capacity, significantly reduced soil chemical properties. These findings suggest that timely application of urea at the right field capacity can mitigate ammonia emission. Therefore, whether soils are amended with or without chicken litter biochar, urea application should be avoided at 50% field capacity especially in irrigated crops.

scholarly journals A climatic study of an urban green space: the Gulbenkian Park in Lisbon (Portugal)

Finisterra ◽  
2012 ◽  
Vol 42 (84) ◽  
Author(s):  
Henrique Andrade ◽  
Rute Vieira
Keyword(s):  
Solar Radiation ◽  
Thermal Comfort ◽  
Green Space ◽  
Urban Green Space ◽  
Mean Radiant Temperature ◽  
Climatic Parameters ◽  
Incident Solar Radiation ◽  
Urban Green ◽  
Isolated Trees ◽  
Radiant Temperature

Measurements of various climatic parameters were carried out in an average-sized green space in the centre of Lisbon (the Fundação Calouste Gulbenkian Park). The aims consisted of assessing the thermal differentiation between the park and the surrounding built-up area and analysing the microclimatic patterns within the park itself. The main results demonstrate that the park is cooler than the built-up area in all the seasons and both during the daytime and at night, but especially so in the daytime during the summer. The most significant microclimatic contrasts were found to occur with respect to solar radiation and mean radiant temperature, with consequences upon the level of thermal comfort. The structure of the vegetation was also found to have a significant microclimatic influence, since the reduction in the level of incident solar radiation brought on by the presence of groups of trees was much larger than that associated with isolated trees.

scholarly journals Minimizing the Cosine Loss in a Solar Tower Power Plant by a Change in the Heliostat Position and Number

2020 ◽  
Vol 9 (3) ◽  
pp. 2302-2304
Keyword(s):  
Solar Radiation ◽  
Tracking System ◽  
Working Fluid ◽  
The Sun ◽  
Incident Solar Radiation ◽  
Concentrated Solar Energy ◽  
Central Receiver ◽  
Receiver System ◽  
Concentrated Solar Radiation ◽  
Solar Rays

Concentrating Solar Power (CSP) focuses sunlight in order to use the heat energy of the sun. In a central receiver system configuration, many mirrors (heliostats) individually track the sun and reflect the concentrated solar energy onto a receiver on top of a tower. The receiver contains the working fluid which is heated by the concentrated solar radiation. The useful energy that absorbed by the water flows through the receiver in solar tower plant depending on the angle between the solar rays and the position of heliostat in the region of work. Heliostat will reflect the incident solar radiation in the direction of the receiver founded in the top of the tower, in order to get a maximum incident solar radiation on the heliostat reflection area. Because of the cosine factor loss effect due to the sun position is variable along the day from sunrise to sunset, which must be in a minimum value, therefore an automated tracking system with dual axes as a control system with sensors had been built and used to stay the sunrays incident on the receiver, and enable the heliostat to flow the sun where it was

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