Simulating ammonia loss from surface applied manure

Abstract

M. 2009. Simulating ammonia loss from surface-applied manure. Can. J. Soil Sci. 89: 357Á367. The land spreading of manure can result in significant nitrogen (N) losses to the atmosphere through ammonia (NH 3 ) volatilization. It is estimated that agricultural activities, including manure spreading contribute approximately 50% of the total global NH 3 emissions. Computer simulation models have been developed in an attempt to predict NH 3 losses resulting from manure spreading. Few models have been validated with success and no validation has been completed for conditions found in eastern Canada. The mechanistic model Volt'Air was implemented and tested to estimate NH 3 emissions using field-based wind tunnel data from three field locations in eastern Canada. The model was validated using data from 27 wind tunnel trials, which measured NH 3 loss over 5Á19 d. Sensitivity analysis revealed that Volt'Air was most sensitive to pH. Good overall agreement was observed between measured results and model simulations over 5Á19 d (R 2 00.91, RMSE 02.9 kg ha(1 ). Short-term flux simulations (kg ha(1 h(1 ) within the first 24 h after spreading were underestimated by 29.5% and fluxes on subsequent days were slightly underestimated by 3.7%. Error with Volt'Air appears to be largely confined to the first day following manure application. Volt'Air offers potential for predicting NH 3 losses (i.e., 5Á19 d) from manure application within eastern Canada. Improving the simulation of short-term pH changes, however, may result in enhanced overall model performance.

Titration and Spectroscopic Measurements of Poultry Litter pH Buffering Capacity

“…However, modeling changes in pH in the manure and in the soil have proven to be difficult (Sommer et al, 2003). For the Volt' Air model, Génermont and Cellier (1997) and Smith et al (2009) noted that the model was particularly sensitive to pH and failed to accurately predict rapid changes in manure pH.…”

Simulation of field NH3 and N2O emissions from slurry spreading

“…However, the same authors found, as a general rule, that the modeling of the denitrification and volatilization processes were less accurate as compared to nitrate leaching, mineralization, nitrification, and N uptake by plants. Regarding the sensitivity to input data, Vol'Air is particularly sensitive to the soil pH (Génermont and Cellier 1997;Smith et al 2009). Both NH 3 and N 2 O emissions are especially sensitive to the soil-water content as a consequence of the sensitivity of Compsoil, Volt'Air, and the STICS submodel for denitrification to the soil water content (Brisson et al 2008;Génermont and Cellier 1997;Hénault and Germon 2000;Langevin 2010;O'Sullivan et al 1999).…”