Assessing crop coefficients of sunflower and canola using two-source energy balance and thermal radiometry

J.M. Sánchez, R. López-Urrea, E. Rubio, J. González-Piqueras and V. Caselles

Agricultural Water Management, 2014, vol. 137, issue C, 23-29

Abstract: A new technique for the local adjustments in crop coefficients is presented. This is an alternative to conventional lysimeter measurements traditionally used for improved irrigation scheduling. The method is based on the combination of a two-source energy balance model and local measurements of radiometric temperatures. Two experimental campaigns were carried out on sunflower and canola in a cropland area located in Barrax, Albacete, in the summer of 2011 and spring of 2012, respectively. Radiometric temperatures of soil and canopy were collected, together with biophysical and meteorological variables. Combining all these data in a two-source energy balance model allowed separation of both the evaporation and transpiration components of the total evapotranspiration (ET). Model results were first compared to local measurements from a lysimeter. Estimation errors around ±0.20mm/h and ±1.0mm/d were observed for both sunflower and canola crops at hourly and daily scales, besides uncertainties lower than 3% for the cumulated ET for the whole campaigns. Results were then used to assess values of the different crop coefficients for this site and the two crops. Comparison with values proposed by FAO56 showed significant discrepancies that yielded to 1–2mm/d uncertainty in terms of daily evaporation and transpiration values, and underestimations of 0.6 and 1.3mm/d, together with estimation errors of ±1.1 and ±1.7mm/d for sunflower and canola, respectively, in terms of daily ET values. Although partitioning of ET needs further study involving field data of evaporation and transpiration, these results reinforce the necessity for the local adjustment of the crop coefficients used as inputs in water balance models, and show the potential of the technique proposed to achieve this goal.

Keywords: Radiometric temperature; Evapotranspiration; Crop coefficient; Two-source energy balance (search for similar items in EconPapers)
Date: 2014
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (7)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0378377414000419
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:agiwat:v:137:y:2014:i:c:p:23-29

DOI: 10.1016/j.agwat.2014.02.002

Access Statistics for this article

Agricultural Water Management is currently edited by B.E. Clothier, W. Dierickx, J. Oster and D. Wichelns

More articles in Agricultural Water Management from Elsevier
Bibliographic data for series maintained by Catherine Liu ().