scholarly journals Reference evapotranspiration estimation using equations with limited data in arid zones

Author(s):  
Norma Guadalupe Sifuentes-Morín ◽  
José Ernesto Frías-Ramírez ◽  
Alan Joel Servín-Prieto ◽  
José Alfredo Montemayor-Trejo

Reference evapotranspiration (ETo), is the most important parameter to estimate water consumption. Nowadays the FAO-56 Penman-Monteith method is the most used in the world to estimate Eto, and recommended as the standard method. The main limitation to use this method is the availability of the requiere weather data. There are step by step calculations to estimate ETo when there is a lack of climate data; with the purpose to estimate the crop water consumption in arid regions, it was evaluated the presicion and aplicability of three equations to estimate this parameter when there is limited climate data. Estimates of Eto were performed for five sites, New Mexico State University main campus and its research centers Leyendecker, Artesia and Fabian Garcia, in new Mexico, USA; as well as the Agriculture and Range Science School of the Juarez University of Durango State in Mexico. The estimates of ETo were done with all required wheater data and with lack of solar radiation and relative humidity data. The presicion of the equations was evaluated by using the relative error and the index of agreement, consiedring as reference the FAO-56 with full weather data.

Irriga ◽  
2018 ◽  
Vol 21 (2) ◽  
pp. 211
Author(s):  
Pedro Ramualyson Fernandes Sampaio ◽  
Neyton De Oliveira Miranda ◽  
José Francismar De Medeiros ◽  
Rozana Maria de Sousa Lima ◽  
Wesley De Oliveira Santos

NECESSIDADE HÍDRICA DA Crotalaria juncea L. EM RESPOSTA À SALINIDADE RESIDUAL DO SOLO PEDRO RAMUALYSON FERNANDES SAMPAIO1; NEYTON DE OLIVEIRA MIRANDA2; JOSÉ FRANCISMAR DE MEDEIROS2; ROZANA MARIA DE SOUSA LIMA3 E WESLEY DE OLIVEIRA SANTOS2 1Engenheiro Agrônomo, Doutorando, Escola Superior de Agricultura Luiz de Queiroz/ESALQ-USP, Programa de Pós-Graduação em Engenharia de Sistemas Agrícolas, Av. Pádua Dias, 11 - São Dimas, 13418-900, Piracicaba - SP, Brasil, [email protected] Agrônomos, Professores Doutores da Universidade Federal Rural do Semi-Árido/UERSA, Departamento de Ciências Ambientais e Tecnológicas, Av. Francisco Mota, 572 – Costa e Silva, 59625-900, Mossoró, RN, Brasil, [email protected]; [email protected]; [email protected]óloga em Recursos Hídricos e Irrigação, Mestre em Irrigação e Drenagem. Instituto Agropolos do Ceará, Rua Barão de Aratanha, 1450 - CEP: 60.050-071 Fortaleza - CE, Brasil, [email protected]  1 RESUMO O trabalho realizado na Fazenda Experimental da Universidade Federal Rural do Semi-Árido em Mossoró, RN, objetivou avaliar a evapotranspiração e o consumo de água pela Crotalaria juncea L. após cultivos consecutivos de cucurbitáceas irrigadas com água de diferentes salinidades. Para isso, foi determinada a evapotranspiração da cultura (ETc) utilizando lisímetros de pesagem, estimou-se a evapotranspiração de referência diária por meio da equação de Penman-Monteith-FAO e, em seguida, foram determinados os coeficientes de cultura (Kc). As variáveis foram analisadas utilizando as médias de dados meteorológicos e dos Kc até a fase de florescimento da cultura. As ETc durante todo o período de 56 dias apresentaram valores de 228,55 e 189,53 mm para as salinidades de 0,6 dS m-1 e 5,0 dS m-1, respectivamente. O maior consumo de água pela Crotalária juncea foi obtido com o menor nível de salinidade residual em todas as fases, com pequena diferença para o consumo no maior nível, indicando tolerância das plantas naquele nível de salinidade. Os Kc obtidos nas três fases de crescimento foram 0,34; 0,89 e 1,41, para a menor salinidade, e 0,29; 0,80 e 1,31 para a maior salinidade. Palavras-chave: irrigação, evapotranspiração, adubo verde.  SAMPAIO, P. R. F.; MIRANDA, N. O.; MEDEIROS, J. F.; LIMA, R. M. S.; SANTOS, W. O.WATER REQUIREMENT OF Crotalaria juncea L. AS A RESPONSE TO SOIL RESIDUAL SALINITY  2 ABSTRACT This work was carried out at the experimental farm of Federal Rural University of Semiarid, at Mossoró, RN, Brazil, aiming at assessing evapotranspiration and water consumption by Crotalaria juncea L. after successive cycles of cucurbitaceae irrigated with water of different salinities. With this purpose, weighing lysimeters were used for crop evapotranspiration (ETc) determination, Penman-Monteith-FAO was used for daily reference evapotranspiration estimation, followed by crop coefficient (Kc) determination. Analysis of variables was made using averages of weather data obtained and of Kc up to crop flowering stage, using electronic spreadsheet. During this 56 days period ETc values of 228.55 and 189.53 mm day-1, were obtained for the lower (0.6 dS m-1) and higher (5.0 dS m-1) salinity levels applied, respectively. Crotalaria juncea presented the higher water consumption with the lower level of residual salinity in all phases, with little difference in relation to the higher level, indicating tolerance to that salinity level. Kc obtained in the three growth phases were 0.34, 0.89 and 1.41 for the lower salinity, and 0.29, 0.80 and 1.31 for the higher salinity. Keywords: irrigation, evapotranspiration, green manure.


2017 ◽  
Vol 132 (3-4) ◽  
pp. 701-716 ◽  
Author(s):  
Gorka Landeras ◽  
Emmanuel Bekoe ◽  
Joseph Ampofo ◽  
Frederick Logah ◽  
Mbaye Diop ◽  
...  

Author(s):  
G. Bracho-Mujica ◽  
P.T. Hayman ◽  
V.O. Sadras ◽  
B. Ostendorf

Abstract Process-based crop models are a robust approach to assess climate impacts on crop productivity and long-term viability of cropping systems. However, these models require high-quality climate data that cannot always be met. To overcome this issue, the current research tested a simple method for scaling daily data and extrapolating long-term risk profiles of modelled crop yields. An extreme situation was tested, in which high-quality weather data was only available at one single location (reference site: Snowtown, South Australia, 33.78°S, 138.21°E), and limited weather data was available for 49 study sites within the Australian grain belt (spanning from 26.67 to 38.02°S of latitude, and 115.44 to 151.85°E of longitude). Daily weather data were perturbed with a delta factor calculated as the difference between averaged climate data from the reference site and the study sites. Risk profiles were built using a step-wise combination of adjustments from the most simple (adjusted series of precipitation only) to the most detailed (adjusted series of precipitation, temperatures and solar radiation), and a variable record length (from 10 to 100 years). The simplest adjustment and shortest record length produced bias of modelled yield grain risk profiles between −10 and 10% in 41% of the sites, which increased to 86% of the study sites with the most detailed adjustment and longest record (100 years). Results indicate that the quality of the extrapolation of risk profiles was more sensitive to the number of adjustments applied rather than the record length per se.


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