scholarly journals A Study of Fitting a Swamp Meadow Ecosystem Evapotranspiration to a Model Based on the Penman-Monteith Equation

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Feng Li ◽  
Bin Wang
Keyword(s):  
Significant Positive Correlation ◽  
Crop Coefficient ◽  
Growing Season ◽  
Linear Increase ◽  
Permafrost Region ◽  
Biotic Factors ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Monteith Equation ◽  
Reference Et

To accurately estimate the magnitude and seasonal dynamics of evapotranspiration (ET) over an important a swamp meadow in the Fenghuoshan permafrost region, we employed the Food and Agriculture Organization- (FAO-) Penman-Monteith (P-M) model. The model was also used to investigate changes in the crop coefficient (kc), which was calculated as the ratio of the measured actual ET (ETafrom the eddy covariance (EC) system) to the reference ET (ET0from the P-M model). The results indicated a reference ET of 900 mm/year from the swamp meadow ecosystem, which was significantly higher than the actual ET (426 mm/year). The reference ET peaked from April to July, while the actual ET was primarily in growing season. The value ofkcexhibited significant seasonal variations within the range 0.3–1.0 with a meankcof 0.55 during the growing season. The dailykcshowed a linear increase withRnandTaand a linear decrease with the VPD. With respect to the biotic factors, the biomass exhibited a significant positive correlation withkc. Thus, a dailykcmodel is developed as a function of the VPD,Rn,Ta, and biomass.

scholarly journals Lysimeter-Based Water Use and Crop Coefficient of Drip-Irrigated Potato in an Arid Environment

Agronomy ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 756 ◽  
Author(s):  
Alataway ◽  
Al-Ghobari ◽  
Mohammad ◽  
Dewidar
Keyword(s):  
Water Use ◽  
Irrigation Schedule ◽  
Crop Coefficient ◽  
Arid Environment ◽  
Crop Evapotranspiration ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Use Efficiency ◽  
Monteith Equation

The determination of the water requirements and crop coefficient (Kc) of agricultural crops helps to create an appropriate irrigation schedule, and with the effective management of irrigation water. The aim of this research was to estimate the water requirement, Kc, and water-use efficiency (WUE) of potato using non-weighing-type lysimeters in four regions of the Kingdom of Saudi Arabia (Qassiem, Riyadh, Al-Jouf, and Eastern). Our results clearly show that the accumulated values of the measured crop evapotranspiration of potato derived from the lysimeters were 573, 554, 592, and 570 mm, while the accumulated values of the predicted crop evapotranspiration from Penman-Monteith equation based on FAO (Food and Agriculture Organization) were 651, 632, 672, and 647 mm for the Qassiem, Riyadh, Al-Jouf, and Eastern regions, respectively. The Kc values of potato obtained from the lysimeters were Kc initial (0.58, 0.54, 0.50, and 0.52), Kc middle (1.02, 1.05, 1.13, and 1.10), and Kc end (0.73, 0.74, 0.74, and 0.75) for the Qassiem, Riyadh, Al-Jouf, and Eastern regions, respectively. Based on the amount of water used and the yield achieved, the highest WUE (3.6 kg m−3) was observed in the Riyadh region, while the lowest WUE (1.5 kg m−3) was observed in the Al-Jouf region.

scholarly journals Prediction of Biome-Specific Potential Evapotranspiration in Mongolia under a Scarcity of Weather Data

Water ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 2470
Author(s):  
Khulan Batsukh ◽  
Vitaly A. Zlotnik ◽  
Andrew Suyker ◽  
Paolo Nasta
Keyword(s):  
Potential Evapotranspiration ◽  
Aridity Index ◽  
Crop Coefficient ◽  
Weather Data ◽  
Gobi Desert ◽  
Area Index ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Practical Guidelines ◽  
Specific Potential

We propose practical guidelines to predict biome-specific potential evapotranspiration (ETp) from the knowledge of grass-reference evapotranspiration (ET0) and a crop coefficient (Kc) in Mongolia. A paucity of land-based weather data hampers use of the Penman–Monteith equation (FAO-56 PM) based on the Food and Agriculture Organization (FAO) guidelines to predict daily ET0. We found that the application of the Hargreaves equation provides ET0 estimates very similar to those from the FAO-56 PM approach. The Kc value is tabulated only for crops in the FAO-56 guidelines but is unavailable for steppe grasslands. Therefore, we proposed a new crop coefficient, Kc adj defined by (a) net solar radiation in the Gobi Desert (Kc adjD) or (b) leaf area index in the steppe region (Kc adjS) in Mongolia. The mean annual ETp obtained using our approach was compared to that obtained by FAO-56 guidelines for forages (not steppe) based on tabulated Kc values in 41 locations in Mongolia. We found the differences are acceptable (RMSE of 0.40 mm d−1) in northern Mongolia under high vegetation cover but rather high (RMSE of 1.69 and 2.65 mm d−1) in central and southern Mongolia. The FAO aridity index (AI) is empirically related to the ETp/ET0 ratio. Approximately 80% and 54% reduction of ET0 was reported in the Gobi Desert and in the steppe locations, respectively. Our proposed Kc adj can be further improved by considering local weather data and plant phenological characteristics.

scholarly journals Modification of FAO Penman–Monteith equation for minor components of energy

2018 ◽  
Vol 50 (2) ◽  
pp. 607-615
Author(s):  
Arman Varmaghani ◽  
William E. Eichinger ◽  
John H. Prueger
Keyword(s):  
Energy Equation ◽  
Minor Components ◽  
Net Radiation ◽  
Obukhov Length ◽  
Available Energy ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Monteith Equation ◽  
Energy Components

Abstract The conventional Food and Agriculture Organization of the United Nations (FAO) Penman–Monteith (P-M) equation requires knowledge of the available energy to estimate reference evapotranspiration (ETo); however, it is common to ignore the minor energy components (MECs). This study was conducted to determine the effect of not including the MECs in the FAO P-M equation. Fifteen-min micrometeorological records of four sites (covered with corn, soybeans, and prairie) in central Iowa, USA, during the years 2007–2012 were investigated. The major/minor components of the energy equation were either measured or estimated by in-situ eddy covariance instruments. It was discovered that, on average, the MECs accounted for at least 13% of daily net radiation, leading to 27% decrease in daily ETo. Therefore, an equation is introduced to estimate MECs as a function of net radiation, air temperature, and Monin–Obukhov length; and another equation is regressed to roughly estimate daily MECs as a function of net radiation and day of the year. The findings in this study suggest a fundamental modification of FAO P-M formula by considering the inclusion of MECs in the energy term.

scholarly journals How Ångström–Prescott Coefficients Alter the Estimation of Agricultural Water Demand in South Korea

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1851
Author(s):  
Hanseok Jeong ◽  
Rabin Bhattarai ◽  
Syewoon Hwang ◽  
Jae-Gwon Son ◽  
Taeil Jang
Keyword(s):  
South Korea ◽  
Global Solar Radiation ◽  
Water Requirement ◽  
Agricultural Water ◽  
Reference Crop Evapotranspiration ◽  
Agricultural Water Management ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Reference Crop ◽  
Monteith Equation

The Food and Agriculture Organization (FAO) Penman–Monteith equation, recognized as the standard method for the estimation of reference crop evapotranspiration (ET0), requires many meteorological inputs. The Ångström–Prescott (A-P) formula containing parameters (i.e., a and b) is recommended to determine global solar radiation, one of the essential meteorological inputs, but may result in a considerable difference in ET0 estimation. This study explored the effects of A-P coefficients not only on the estimation of ET0, but also on the irrigation water requirement (IWR) and design water requirement (DWR) for paddy rice cultivation, which is the largest consumer of agricultural water in South Korea. We compared and analyzed the estimates of ET0, IWR, and DWR using the recommended (a = 0.25 and b = 0.5) and locally calibrated A-P coefficients in 16 locations of South Korea. The estimation of ET0 using the recommended A-P coefficients produced significant overestimation. The overestimation ranged from 3.8% to 14.0% across the 16 locations as compared to the estimates using the locally calibrated A-P coefficients, and the average overestimation was 10.0%. The overestimation of ET0 corresponded to a variation of 1.7% to 7.2% in the overestimation of the mean annual IWR, and the average overestimation of the IWR was 5.1%. On average, the overestimation was slightly reduced to 4.8% in DWR estimation, since the effect of A-P coefficients on the IWR estimation decreased as the IWR increased. This study demonstrates how the use of A-P coefficients can alter the estimation of ET0, IWR, and DWR in South Korea, which underscores the importance of their proper consideration in agricultural water management.

scholarly journals Evapotranspiration and crop coefficient for potato in organic farming

2013 ◽  
Vol 33 (1) ◽  
pp. 201-211 ◽  
Author(s):  
Daniel F. de Carvalho ◽  
Dione G. da Silva ◽  
Hermes S. da Rocha ◽  
Wilk S. de Almeida ◽  
Eraldo da S. Sousa
Keyword(s):  
Water Consumption ◽  
Solanum Tuberosum L ◽  
Meteorological Data ◽  
Crop Coefficient ◽  
Climatic Conditions ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Historical Series ◽  
The One ◽  
Crop Coefficients

The aim of this study was to quantify the water consumption and the crop coefficients (Kc) for the potato (Solanum tuberosum L.), in Seropédica, Rio de Janeiro (RJ), Brazil, under organic management, and to simulate the crop evapotranspiration (ETc) using the Kc obtained in the field and the ones recommended by the Food and Agriculture Organization (FAO). The water consumption was obtained through soil water balance, using TDR probes installed at 0.15m and 0.30m deep. At the different stages of development, the Kc was determined by the ratio of ETc and reference evapotranspiration, obtained by Penman-Monteith FAO 56. The crop coefficients obtained were 0.35, 0.45, 1.29 and 0.63. The accumulated ETc obtained in the field was 109.6 mm, while the ETc accumulated from FAO's Kc were 142.2 and 138mm, respectively, considering the classical values and the values adjusted to the local climatic conditions. The simulation of water consumption based on meteorological data of historical series from 1961 to 2007 provided higher value of ETc when compared with the one obtained in the field. From the meteorological data of historical series, it was observed that the use of Kc recommended by FAO may overestimate the amount of irrigation water by 9%, over the same growing season.

scholarly journals Evaluation of Potential Evapotranspiration Based on CMADS Reanalysis Dataset over China

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1126 ◽  
Author(s):  
Ye Tian ◽  
Kejun Zhang ◽  
Yue-Ping Xu ◽  
Xichao Gao ◽  
Jie Wang
Keyword(s):  
Wind Speed ◽  
Solar Radiation ◽  
Potential Evapotranspiration ◽  
Swat Model ◽  
Western China ◽  
Reanalysis Dataset ◽  
The North ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Monteith Equation

Potential evapotranspiration (PET) is used in many hydrological models to estimate actual evapotranspiration. The calculation of PET by the Food and Agriculture Organization of the United Nations (FAO) Penman–Monteith method requires data for several meteorological variables that are often unavailable in remote areas. The China Meteorological Assimilation Driving Datasets for the SWAT model (CMADS) reanalysis datasets provide an alternative to the use of observed data. This study evaluates the use of CMADS reanalysis datasets in estimating PET across China by the Penman–Monteith equation. PET estimates from CMADS data (PET_cma) during the period 2008–2016 were compared with those from observed data (PET_obs) from 836 weather stations in China. Results show that despite PET_cma overestimating average annual PET and average seasonal in some areas (in comparison to PET_obs), PET_cma well matches PET_obs overall. Overestimation of average annual PET occurs mainly for western inland China. There are more meteorological stations in southeastern China for which PET_cma is a large overestimate, with percentage bias ranging from 15% to 25% for spring but a larger overestimate in the south and underestimate in the north for the winter. Wind speed and solar radiation are the climate variables that contribute most to the error in PET_cma. Wind speed causes PET to be underestimated with percentage bias in the range −15% to −5% for central and western China whereas solar radiation causes PET to be overestimated with percentage bias in the range 15% to 30%. The underestimation of PET due to wind speed is offset by the overestimation due to solar radiation, resulting in a lower overestimation overall.

scholarly journals CALIBRATION OF THE HARGREAVES-SAMANI EQUATION FOR SPECIFIC PERIODS OF THE YEAR IN THE MUNICIPALITY OF JAÍBA-MG, BRAZIL

2017 ◽  
Vol 25 (5) ◽  
pp. 445-453
Author(s):  
Anunciene Barbosa Duarte ◽  
Lucas Borges Ferreira ◽  
Edson Fagne Dos Santos
Keyword(s):  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Climatic Conditions ◽  
Crop Water ◽  
Climatic Effects ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Crop Water Demand ◽  
Limited Application ◽  
Monteith Equation

Reference evapotranspiration (ET0) explains the climatic effects on crop water demand. The Food and Agriculture Organization (FAO) recommends the Penman Monteith equation as a standard method for estimating ET0. However, because this equation requires a large amount of meteorological data, it has limited application. An alternative is the Hargreaves-Samani (HS) equation, which only requires air temperature data, and can be calibrated to specifc locations and periods. The present study aimed to calibrate the empirical parameters (coeffcients and exponent) of the HS equation for specifc periods of the year, as well as evaluate the behavior and calibration of this equation throughout the year in the municipality of Jaíba-MG, Brazil. The daily meteorological data from 1996 to 2011 were gathered from a weather station located in the municipality of Jaíba-MG. A general calibration was performed per semester, per season, per month, and during periods with similar climatic conditions. The calibration of the HS equation, in all of the forms studied, promoted better ET0estimations. The calibrations for specifc periods of the year only promoted slight increases in performance in relation to the general calibration, therefore they, in general, presented equal performance to each other.

scholarly journals Estimation of the crop coefficient (kc) for bell pepper under greenhouse conditions

2019 ◽  
Vol 23 (10) ◽  
pp. 741-746
Author(s):  
Marcelo Z. Lorenzoni ◽  
Roberto Rezende ◽  
Fernando A. S. Santos ◽  
Álvaro H. C. de Souza ◽  
Cássio de C. Seron ◽  
...  
Keyword(s):  
Water Consumption ◽  
Reference Evapotranspiration ◽  
Crop Coefficient ◽  
Bell Pepper ◽  
Weather Station ◽  
Total Water ◽  
Food And Agriculture ◽  
Total Water Consumption ◽  
Food And Agriculture Organization ◽  
Average Consumption

ABSTRACT This study aimed to determine the crop coefficient (kc) and respective water consumption of the Magali R. bell pepper hybrid cultivated in a protected environment from May to September 2015. Reference evapotranspiration was estimated using the Modified Penman-Monteith method and data were collected from an automatic weather station installed inside the greenhouse at the Universidade Estadual de Maringá, in the municipality of Maringá, PR, Brazil (23° 25’ 57’’ S, 51° 57’ 8’’ W, and altitude of 542 m). Evapotranspiration was measured using constant water table lysimeters. The total water consumption of the bell pepper crop was 282 mm and the average consumption was 2.35 mm d-1. The maximum evapotranspiration was 5.37 mm d-1. Crop coefficient values for the bell pepper were 0.86, 1.55, and 1.4 for the initial, intermediate, and final stages, respectively, which were higher than those recommended by the Food and Agriculture Organization.

Food waste and dynamic complex systems: The case of Peru and a solution model proposal Part 1: Peruvian Anchoveta (Engraulis ringens)

2020 ◽  
Author(s):  
Carlos A Almenara
Keyword(s):  
United Nations ◽  
Complex Systems ◽  
Revenue Management ◽  
Food Waste ◽  
Intelligent Systems ◽  
Solution Model ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Engraulis Ringens ◽  
The United Nations

[THE MANUSCRIPT IS A DRAFT] According to the Food and Agriculture Organization of the United Nations (FAO, 2020), food waste and losses comprises nearly 1.3 billion tonnes every year, which equates to around US$ 990 billion worldwide. Ironically, over 820 million people do not have enough food to eat (FAO, 2020). This gap production-consumption puts in evidence the need to reformulate certain practices such as the controversial monocropping (i.e., growing a single crop on the same land on a yearly basis), as well as to improve others such as revenue management through intelligent systems. In this first part of a series of articles, the focus is on the Peruvian anchoveta fish (Engraulis ringens).

To the Empire and Beyond

2018 ◽  
Author(s):  
Gregory A. Barton
Keyword(s):  
Second World War ◽  
World War ◽  
Chemical Fertilizers ◽  
Basic Principles ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Organic Farmers ◽  
Southern Rhodesia ◽  
The Government ◽  
Second World

This chapter traces the expansion of industrial agricultural methods after the Second World War. Western governments and the Food and Agriculture Organization pushed for increased use of chemical fertilizers to aid development and resist Soviet encroachment. Meanwhile small groups of organic farmers and gardeners adopted Howard’s methods in the Anglo-sphere and elsewhere in the world. European movements paralleled these efforts and absorbed the basic principles of the Indore Method. British parliament debated the merits of organic farming, but Howard failed to persuade the government to adopt his policies. Southern Rhodesia, however, did implement his ideas in law. Desiccation theory aided his attempts in South Africa and elsewhere, and Louise Howard, after Albert’s death, kept alive a wide network of activists with her publications.

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