ARTICLE Surface energy flux measurements in a flooded and an aerobic rice field using a single eddy-covariance system Daniele Masseroni • Arianna Facchi • Marco Romani • Enrico Antonio Chiaradia • Olfa Gharsallah • Claudio Gandolfi Received: 18 February 2014 / Revised: 6 August 2014 / Accepted: 16 August 2014 Ó The International Society of Paddy and Water Environment Engineering and Springer Japan 2014 Abstract About 90 % of the global rice production takes place in Asia, while European production is quantitatively modest. Italy is the Europe’s leading producer, with over half of total production concentrated in a large, traditional paddy rice area in the north of the country. High irrigation require- ment for continuous flooding encourages the adoption of water saving techniques. In 2013, an intense monitoring activity was conducted on two fields characterized by con- tinuous flooding and intermittent irrigation regimes, with the aim of comparing their agronomical and hydrological effects, including their influence on the energy balance. An eddy covariance station was installed on the levee between the two fields, to monitor latent (LE) and sensible (H) heat fluxes as a function of wind direction. Additionally, the fields were instrumented with net radiometers, soil heat flux (G) plates, thermistors, tensiometers, and multilevel moisture probes. Three footprint models were applied to determine position and size of the footprint area at each monitoring time step, providing similar results. Two half-hourly turbulent fluxes datasets were obtained, one for each irrigation regime, each one comprising about 10 % of the daytime time steps over the agricultural season. The reliability of the monitoring per- formed with a single EC station was confirmed by the energy balance closure (H ? LE versus R n -G), showing an imbal- ance lower than 10 % for both the regimes. A detailed ana- lysis of the effect of the storage terms on the ground heat flux estimation and a more thorough analysis of the radiation balance for the two plots were also performed. Keywords Surface energy fluxes Á Eddy covariance technique Á Evapotranspiration Á Flooded rice Á Aerobic rice Á Northern Italy Introduction Rice is of great importance both from a food supply point of view, since it represents the main food in the diet of over half the world’s population, and from a water resources point of view, since it consumes almost 40 % of the water amount used for irrigation (Bouman et al. 2007a). About 90 % of global production takes place in Asia (EURO- STAT 2013), while European production is quantitatively modest (about 3 million tons). However, Italy is the Eur- ope’s leading producer, with over half of total production and a high quality level. The most important rice-growing region consists of the portion of the Po river plain located east of the Ticino river, straddling the regions of Lombardy and Piemont in northern Italy. Rice is traditionally grown in bunded fields that are kept flooded from crop establishment to close to harvest by maintaining a ponded water depth of about 5–10 cm (Bouman et al. 2007a). Owing to this particularly demanding water management and to the large harvested area, it is estimated that the total seasonal water input to irrigated rice (rainfall plus irrigation) can be up to 2–3 times more than for other cereals, like wheat or maize (Tuong and Bhuiyan 1999, Tuong et al. 2005). The increasing scarcity of water threatens the sustain- ability of the irrigated rice production system and hence the food security and livelihood of rice producers and D. Masseroni (&) Á A. Facchi Á E. A. Chiaradia Á O. Gharsallah Á C. Gandolfi Department of Agricultural and Environmental Sciences (DiSAA), Universita ` degli Studi di Milano, Via Celoria 2, 20133 Milan, Italy e-mail: daniele.masseroni@unimi.it M. Romani Ente Nazionale Risi (NRRC), Strada per Ceretto 4, 27030 Pavia, Italy 123 Paddy Water Environ DOI 10.1007/s10333-014-0460-0