A Review of Chamber and Micrometeorological Methods to Quantify NH₃ Emissions from Fertilisers Field Application

Table 2

Main dynamic chambers characteristics and reference studies.

Chamber method	Measurement surface area (m)	Airspeed (m s^−1)	Chamber characteristics	Pros and cons	Reference
	0.25^2	Variable (0.07 max)	It consisted of a polycarbonate chamber (50 cm by 50 cm) open to one side and the bottom.	(i) Minimizes the temperature and wind speed differences with outside.; (ii) Simulates the natural wind speed.; (iii) Condensation on the internal walls during the night.	Vallis et al. [60]
	1^2	0.04–3.77	Wind tunnel made of 2 parts: a tunnel formed from a transparent polycarbonate sheet and a steel circular duct, connected with the fan.	(i) Provides natural sward condition inside it.; (ii) Obtains internal airspeed similar to outside one.; (iii) Condensation inside of the tunnel occurs.	Lockyer [61]
	2^2	0.3–3.5	Wind tunnel characterised by 6 following chambers: inlet, calming section, testing section, mixing section, 2 axial fans section, and outlet.	(i) Alteration of microclimatic conditions inside the chambers is avoided by automatic adjusting of inside air.; (ii) The testing section is covered by a transparent foil to not alter the irradiation.	Braschkat et al. [62]
	0.32^2	0.33	Wind tunnel based on Lindvall [63] hood consists of an emission chamber 25 cm high, situated between a divergent diffuser and a convergent duct, respectively, 50 cm and 15 cm long.	(i) Aerodynamic disadvantages of the primal geometries are corrected, introducing some flow devices (flat vanes, perforated baffle, and extension duct).	Jiang et al. [64]
	415^2	Variable	Dynamic chamber characterised by 4 chambers placed onto the emitting surface. Air is sucked from them simultaneously by a pump and the ammonia concentrations are measured by a Dräger tube.	(i) High reliability of this method for comparative studies.; (ii) No electricity and laboratory analysis.; (iii) Low air exchange rate could lead to an underestimation of flow rate.	Roelcke et al. [56]