AMMONIA AND WATER FLUXES MODELLING OVER AGRICULTURAL PLOTS

1. AMMONIA AND WATER FLUXES MODELLING OVER AGRICULTURAL PLOTS AMMONIA AND WATER FLUXES MODELLING OVER AGRICULTURAL PLOTS AMMONIA AND WATER FLUXES MODELLING OVER AGRICULTURAL PLOTS Gianfranco Rana CRA – Unità di ricerca per i Sistemi Colturali degli Ambienti caldo aridi, Bari INRA – Unité Mixte Recherche Environnement et Grandes Cultures, Grignon, France

2. Summary • “FIDES 3D” • Transport model • The sources and the sinks of ammonia • “Volt’air” • Mechanistic model • Ammonia volatilization • Water fluxes • A review on the reference evapotranspiration

3. Problems with NH3 sampling and flux measure • Tendence to make strong hydrogen link with H2O • Adsorbment and memory effect • Punctual sources, spatial variability • Time variability • Dispersion, possible minimum deposition

4. NH3 volatilization from agricultural system • The process: NH3 transfert from nitrogen liquid solution to the air in contact • N applied losses: Urea: 10-25%; Slurry: > 60% • It dipends on (Sommer et al., 2003): • NH4+ concentration • Temperature, solar radiation, wind speed, rain, air humidity … • Turbolent transport • pH • Evaporation rate, dew • Soil type, soil moisture • Application techniques

5. FIDES3D: Flux Interpretation by Dispersion and Exchange over Short range in three Dimensions Loubet et al., 2001; Loubet et al., 2010 Hypothesis • Advection-diffusion equation (Philip, 1959) • Power laws for wind speed and vertical diffusivity profiles (Huang, 1979) • No chimical reactions in atmosphere and surface • Inputs: • Turbulence of atmosphere • Concentration of NH3 at background and level z • Fetch, geometrical properties of the source

6. Source strength in (xs, ys,zs): function of Rb(u*, B) e Cc Dispersion Function Principles Superposingprinciple It relates the concentration of scalar in a point of the field to the source strengthin another point (Raupach, 1989; Thompson, 1998)

7. Surface/air NH3 exchange • The resistance analogy approach • a stomatal pathway • a cuticular pathway Ammonia has a canopy compensation point =concentration value for which the flux is zero

8. Set-up

9. Final considerations on FIDES3D • the following input are needed: (1) the NH3 air concentration at least at one height above the surface (2) the background concentration (3) the standard micrometeorological variables acquired usually by a sonic anemometer (4) the dimension of the local source along the wind direction and the fetch where the NH3 is measured • From the computational point of view • the cuticular resistance Rw and the strength Ss are considered as unknown and they are inferred with a standard iterative method using the classical Netwon-Raphton technique • once Rw and Ss are calculated the advection flux Fa of ammonia is estimated by a numerical integration of the advection-dispersion equation

10. Volt’air (Génermont and Cellier, 1997) Transformation and movement of ammoniacalnitrogen in the soil Rachhphal-Sing and Nye (1986a; 1986b; 1986c; 1988) Ammonia volatilization from the surface Van der Molen et al. (1990) Transfer of ammonia from the surface toward the atmosphere

11. Starting hypothesis • Urea is converted to ammoniacal nitrogen and carbonate within a few hours after application • The simulation takes place for a short period (week), thus nitrogen transformations by organic matter mineralization, ammoniacal uptake by the plants, oxidation and/or nitrification are not taken into account for • The mineralization of the organic nitrogen from the slurry is considered to be negligible

12. Transfer of ammonia gas to the atmosphere • The flux of ammonia is bidirectional and the source is not known a priori • Model of local advection (Itier and Perrier, 1976) • Change in the surface flux as a function of the distance from the leading edge in the wind direction (fetch) and the difference in the surface concentration for an abrupt change in the surface concentration

13. Inputs: 1. general information

14. Inputs: 2. agriculturalpractices

15. Inputs: 3. soilhydraulicproperties

16. Inputs: 4. physical and chemicalproperties

17. Inputs: 5. Soil

18. Inputs: 6. Meteorology

19. Slurry spreading • Landriano (45° 18‘; 9° 15' E) (Università di Milano) • Field ~ 4 ha bare soil • 27-31 March 2009 • Surface spreading of cow slurry, filling after 24 h • ~184 kgN ha-1 ~93 kgN-NH4+ ha-1 15 cm

20. NH3 Flux by FIDES3D Soil filling Start spreading

21. Urea spreading • Rutigliano (CRA-SCA Bari) • 17-29 July 2008 • Grain Sorghum (~ 2 ha) • Urea application: • 30 kgN ha-1 (01/07/2008) • 90 kgN ha-1 (16/07/2008) • 120 kgN ha-1 (22/07/2008) • Irrigation by aspersion

22. NH3 Flux by FIDES3D

23. Cumulate values

24. WATER FLUXES Katerji, N., Rana, G., 2011. Crop reference evapotranspiration: a discussion of the concept, analysis of the process and validation. Water Resources Management, on line since 5 January 2011. DOI 10.1007/s11269-010-9762-1

25. Analisi teorica e fisica dell’evaporazione • Penman (1946): evaporazione da superficie di acqua libera • Monteith (1963-1965): evapotraspirazione da una coltura teorica • Thom (1975-1978): formalizzazione della resistenza aerodinamica • Perrier (1975-1983): evapotraspirazione da una coltura reale

26. Evaporazione potenziale (Penman) • Nessun controllo biologico da parte di una eventuale coltura • Nessun controllo dovuto alla struttura di una eventuale coltura • Può rappresentare bene la domanda evaporativa dell’atmosfera

27. Evaporazione potenziale di una coltura (Perrier) Una coltura con acqua sempre disponibile oppone solo una resistenza dovuta alla sua struttura

28. Evaporazione potenziale di una coltura (Perrier) • Situazione teorica • Solo dopo una pioggia o rugiada • o irrigazione per aspersione • Le due quantità possono essere uguali • per il prato in particolari condizioni

29. Evapotraspirazione (Monteith) Se non vi è nessuna saturazione a nessun livello allora la coltura oppone una resistenza biologica: la resistenza colturale Questa varia tra un minimo, quando la coltura è in buone condizioni idriche e un massimo quando è completamente secca

31. Relazioneresistenza stomatica/resistenza colturale Monteith et al. (1965)

32. SintesiPenman -> Perrier -> Monteith • Situazione teorica • Solo dopo una pioggia o rugiada o irrigazione per aspersione • Le due quantità possono essere uguali per il prato in particolari condizioni

33. Modello di Penman-Monteith versione Perrier • , ρ, γ, cp quasi constanti • A, energia disponibile = Rn-G • Rn, radiazione netta • G, flusso di calore nel suolo • D, deficit di pressione di vapore • ra, resistenza aerodinamica • rc, resistenza colturale Le misure dovrebbero esser fatte SULLA COLTURA

34. Prato di riferimento • Ben irrigato • Ben concimato • 10 - 15 cm • Esteso • Solo una specie (lolium perenne L.)

35. Penman-Monteith FAO56 • ET0 calcolata sopra un prato di riferimento • Scala temporale • Cn=37 e Cp=0.24 • Cn=900 e Cp=0.34 Resistenza colturale costante

37. Storia della resistenza colturale costante per un prato Allen et al., (1989; 1994; 1998; 2006) rc=70 s/m rc=50 s/m

38. Monteith, J.L., 1965. Evaporation and the environment. XIXth Symposia of the Society for Experimental Biology. In the State and Movement of Water in Living Organisms. University Press, Swansea, Cambridge, pp. 205–234

39. J. Appl. Ecology, 1965 *Rothamsted, UK

40. Pubblicazioni • Katerji, N., Rana, G., Mastrorilli, M., 2010. Modelling of actual evapotranspiration in open top chambre (OTC) at daily and seasonal scale: Multiannual validation on soybean in contrasted conditions of water stress and air ozone concentration. European Journal of Agronomy, 33, 218-230 • Rana, G., Katerji, N., Ferrara, R., Martinelli, N., 2010. An operational model to estimate hourly and daily crop evapotranspiration in hilly terrain: validation on wheat and oat crops. Theoretical and Applied Climatology (on line, under press) • Katerji, N., Rana, G., Fahed, S., 2010. Parameterizing canopy resistance using mechanistic and semi-empirical estimates of hourly evapotranspiration: critical evaluation for irrigated crops in the Mediterranean. Hydrological Processes (on line, under press) • Loubet, B., Gènermont, S., Ferrara, R., Bedos, C., Decuq, C., Personne, E., Fanucci, O., Durand, B., Rana, G., Cellier, P., 2010. An inverse model to estimate ammonia emissions from fields. Eur. J. Soil Sci (on line, under press) • Katerji, N., Rana, G., 2011. Crop reference evapotranspiration: a discussion of the concept, analysis of the process and validation. Water Resources Management, (on line, under press). • R. M. Ferrara, B. Loubet, P. Di tommasi, T. Bertolini, V. Magliulo, P. Cellier, G. Rana. Evaluation of eddy covariance measurement of ammonia fluxes with a Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS) (in preparazione). • R. M. Ferrara, B. Loubet, P. D. Palumbo, V. Magliulo, G. Rana. Dynamic of ammonia volatilization over sorghum fertilized under Mediterranean conditions (in preparazione).

41. Grazie a tutti