In-situ partitioning of evaporation and transpiration components using a portable evapotranspiration dome—A case study in Tall Fescue (Festuca arundinacea)

Alam, Muhammad Shahinur; Lamb, David; Rahman, Muhammad Moshiur

doi:10.1016/j.agwat.2018.10.042

Cited by 9 publications

(3 citation statements)

References 54 publications

(64 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The shape of the total transpiration-LAI curves, specifically the tendency towards saturation at higher LAI, is similar to that reported in pasture [24] and wheat [49], where the results were expressed in terms of a basal crop coefficient (K cb ). A controlled atmosphere experiment involving the same pasture species (tall fescue), where the transpiration was separately calculated through isotopic observation, found that transpiration can be as high as 0.55 mm hr -1 for an LAI of 4, which is also very close to the model-predicted values in this experiment [31].…”

Section: Resultssupporting

confidence: 79%

See 1 more Smart Citation

A Canopy Transpiration Model Based on Scaling Up Stomatal Conductance and Radiation Interception as Affected by Leaf Area Index

Alam

Lamb

Warwick

2021

Water

Self Cite

View full text Add to dashboard Cite

Estimating transpiration as an individual component of canopy evapotranspiration using a theoretical approach is extremely useful as it eliminates the complexity involved in partitioning evapotranspiration. A model to predict transpiration based on radiation intercepted at various levels of canopy leaf area index (LAI) was developed in a controlled environment using a pasture species, tall fescue (Festuca arundinacea var. Demeter). The canopy was assumed to be a composite of two indistinct layers defined as sunlit and shaded; the proportion of which was calculated by utilizing a weighted model (W model). The radiation energy utilized by each layer was calculated from the PAR at the top of the canopy and the fraction of absorbed photosynthetically active radiation (fAPAR) corresponding to the LAI of the sunlit and shaded layers. A relationship between LAI and fAPAR was also established for this specific canopy to aid the calculation of energy interception. Canopy conductance was estimated from scaling up of stomatal conductance measured at the individual leaf level. Other environmental factors that drive transpiration were monitored accordingly for each individual layer. The Penman–Monteith and Jarvis evapotranspiration models were used as the basis to construct a modified transpiration model suitable for controlled environment conditions. Specially, constructed self-watering tubs were used to measure actual transpiration to validate the model output. The model provided good agreement of measured transpiration (actual transpiration = 0.96 × calculated transpiration, R2 = 0.98; p < 0.001) with the predicted values. This was particularly so at lower LAIs. Probable reasons for the discrepancy at higher LAI are explained. Both the predicted and experimental transpiration varied from 0.21 to 0.56 mm h−1 for the range of available LAIs. The physical proportion of the shaded layer exceeded that of the sunlit layer near LAI of 3.0, however, the contribution of the sunlit layer to the total transpiration remains higher throughout the entire growing season.

show abstract

Section: Resultssupporting

confidence: 79%

“…Whether calculated by the "big-leaf" or "dual-leaf" method, LAI remains the most significant determinant of canopy conductance [8,20], and it therefore plays an important role in the estimation of transpiration. It is evident from previous studies that transpiration is linked to the canopy LAI [24][25][26][27].…”

Section: Introductionmentioning

confidence: 98%

A Canopy Transpiration Model Based on Scaling Up Stomatal Conductance and Radiation Interception as Affected by Leaf Area Index

Alam

Lamb

Warwick

2021

Water

Self Cite

View full text Add to dashboard Cite

show abstract

“…Além disso, esses mesmos autores afirmam que a refletância espectral de culturas agrícolas pode fornecer uma estimativa de forma indireta dos valores de Kc. Alam et al (2019) encontraram modelos com ajuste adequados para coeficiente de cultura (Kc), coeficiente de cultura basal (Kcb) e coeficiente de evaporação (Ke) em função do NDVI para pastagem. Por meio de sensoriamento remoto, o NDVI foi usado para prever os valores de Kc com ajustes satisfatórios em trigo (FARG et al, 2012) e cana de açúcar (ALFACE et al, 2019).…”

Section: Estimativa Dos Coeficientes Técnicos Para Manejo Da Irrigaçãounclassified

Germinação de sementes, produção de mudas e obtenção de parâmetros relacionados ao manejo da irrigação em Physalis peruviana L.

Freitas¹

View full text Add to dashboard Cite

O cultivo de Physalis peruviana tem se destacado como alternativa promissora para pequenos e médios produtores, em decorrência da valorização da cultura. Entretanto, as informações quanto ao cultivo dessa espécie em condições edafoclimáticas brasileiras ainda são escassas, principalmente em relação aos parâmetros de cultivo e manejo da irrigação. Portanto, objetivou- se com a presente pesquisa avaliar as características morfológicas e hídricas de sementes, mudas e plantas de Physalis peruviana. Desta forma, foram conduzidos experimentos de janeiro de 2019 a agosto de 2021, no Laboratório de Sementes do Departamento de Agronomia e na Área Experimental de Irrigação e Drenagem do Departamento de Engenharia Agrícola, pertencentes a UFV. Para os estudos da germinação das sementes, estas foram submetidas primeiramente a diferentes temperaturas (10, 15, 20, 25, 30, 35, 40 e 20-30 °C) e posteriormente foi realizada a combinação de diferentes temperaturas (20, 20/30, 30 e 40 °C) e potenciais osmóticos (0; -0,3; -0,6 e -0,9 MPa). Para os estudos relacionados às mudas foi avaliada a interação entre quatro recipientes (polipropileno de 200 cm³, recipientes de polipropileno de 100 cm 3 , sacos de polietileno de 400 cm³, bandejas de poliestireno expandido de 128 células de 18 cm³) e seis substratos (solo + areia, substrato comercial Maxplant ® , solo, solo + areia + substrato comercial, solo + areia + substrato comercial + esterco cama de aviário; proporção: 1:1:1:2 e solo + areia + substrato comercial + esterco bovino curtido; proporção: 1:1:1:2). Os estudos de demanda hídrica e coeficiente de cultura (Kc) foram conduzidos em estação lisimétrica, com quatro tratamentos: cultivo de P. peruviana sem cobertura de papel (C); cultivo com papel reciclado como cobertura (CP); lisímetro ocupado com apenas papel reciclado (P); e lisímetro cultivado com grama batatais (G) e realizadas avaliações quanto a fenologia da cultura, características dos frutos, trocas gasosas, produtividade e índice de vegetação pelo NDVI. A determinação do ponto de murcha permanente ocorreu em casa de vegetação com cultivo em vasos. Os tratamentos foram constituídos pela combinação de solos com texturas distintas (solo franco- argilo-arenoso e arenoso) e onze períodos de imposição de déficit hídrico. Com os testes de germinação foi possível determinar as temperaturas em que as sementes de Physalis peruviana apresentaram melhor desempenho germinativo, sendo na faixa de temperaturas entre 20 e 35 °C. A baixa disponibilidade hídrica afetou negativamente as características de germinação das sementes. Para a produção de mudas, destacou-se o recipiente de maior volume e o substrato S6 (solo + areia + substrato comercial + esterco bovino curtido na proporção: 1:1:1:2) como os que proporcionaram melhor desenvolvimento e qualidade das plantas produzidas. Para determinação dos parâmetros técnicos de cultivo de P. peruviana, observou-se que o uso do papel como cobertura do solo reduziu significativamente o consumo hídrico, principalmente na fase inicial e final da cultura, reduzindo também os valores de Kc. Apesar dessa redução hídrica, não houve prejuízos às características fisiológicas e agronômicas da cultura. Já em relação ao ponto de murcha permanente observa-se que pode variar de acordo com a textura do solo e do desenvolvimento da cultura. Palavras-chave: Crescimento de plântula. Emergência. Déficit hídrico. Estádios de desenvolvimento. Consumo hídrico.

show abstract

Actual and standard crop coefficients for semi-natural and planted grasslands and grasses: a review aimed at supporting water management to improve production and ecosystem services

et al. 2023

View full text Add to dashboard Cite

Natural and planted grasslands play a very important role in agriculture as source of various ecosystem services, including carbon sequestration and biodiversity, and are responsible for a large fraction of agricultural water use in rainfed and irrigated fields. It is, therefore, relevant to precisely know their water use and vegetation requirements with consideration of relevant climate, from extremely cold, dry, with long winter seasons, to tropical humid and hot climates, thus with a large variability of vegetation. Semi-natural grasslands are basically used for grazing and mainly refer to highland pastures and meadows, steppes, savannas, pampas, and mixed forest systems. The FAO method to compute crop (vegetation) evapotranspiration (ETc) through the product of a crop coefficient (Kc) by the reference evapotranspiration (ETo) is adopted. The selected papers were those where actual ETc (ETc act) was derived from field observations and ETo was computed with the FAO56 definition, or with another method that could be referred to the former. Field derived ETc act methods included soil water balance, Bowen ratio and eddy covariance measurements, as well as remote sensing vegetation indices or surface energy balance models, thus reviewed Kc act (ETc act/ETo) values were obtained from field data. These Kc act refer to initial, mid-season and end season (Kc act ini, Kc act mid, Kc act end) when reported values were daily or monthly; otherwise, only average values (Kc act avg) were collected. For cases relative to cold or freezing winters, data refer to the warm season only. For grasses cut for hay, Kc act ini, Kc act mid, and Kc act end refer to a cut cycle. Kc act values rarely exceeded 1.25, thus indicating that field measurements reported did respect the available energy for evaporation. Overall, Kc act mid for semi-natural grasslands in cold climates were lower than those in hot climates except when available water was high, with Kc act mid for meadows and mountain pastures generally high. Steppes have Kc act mid values lower than savannas. Grasses commonly planted for hay and for landscape generally showed high Kc act mid values, while a larger variability was observed with grasses for grazing. The collected Kc act values were used to define standard Kc values for all grassland and grasses. Nevertheless, the tabulated Kc act are indicative values of Kc to be used for actual water management purposes and/or irrigation scheduling of planted grasslands. It is expected that a better knowledge of the standard and/or indicative Kc values for a wide variety of grasslands and grasses will support better management aimed to improve grass productivity and ecosystem services, including biodiversity and carbon sequestration.

show abstract

In-situ partitioning of evaporation and transpiration components using a portable evapotranspiration dome—A case study in Tall Fescue (Festuca arundinacea)

Cited by 9 publications

References 54 publications

A Canopy Transpiration Model Based on Scaling Up Stomatal Conductance and Radiation Interception as Affected by Leaf Area Index

A Canopy Transpiration Model Based on Scaling Up Stomatal Conductance and Radiation Interception as Affected by Leaf Area Index

Germinação de sementes, produção de mudas e obtenção de parâmetros relacionados ao manejo da irrigação em Physalis peruviana L.

Actual and standard crop coefficients for semi-natural and planted grasslands and grasses: a review aimed at supporting water management to improve production and ecosystem services

Contact Info

Product

Resources

About