Simulated management effects on ammonia emissions from field applied manure.

A need exists to improve the utilization of manure nutrients by minimizing NH(3) emissions from land application of manure. Management strategies to reduce NH(3) emissions are available; however, few have been validated under Canadian conditions. A well tested and accurate simulation model, however, can help overcome this challenge by determining appropriate management strategies for a given set of field conditions. The Volt'Air simulation model was utilized to estimate NH(3) volatilization from manure spreading for various manure spreading considerations under a range of atmospheric conditions typically encountered in eastern Canada. Considerations included: (i) soil liming, (ii) time of day of manure spreading, (iii) rainfall (timing and amount) and (iv) manure incorporation (timing, depth and manure coverage). Results demonstrated that liming to increase soil pH, increased NH(3) emissions by 3.3 kg ha(-1) for each increment of 0.1 pH (up to a 1.5 total increase), over no liming at 34.6 kg ha(-1). For each hour delay in manure spreading past 0800 h, NH(3) losses were reduced by 1.5 kg ha(-1). Rainfall (10mm) at least 20 h after manure application reduced losses, with increased reductions at higher rainfall amounts. Incorporation soon (1h) after application was best for NH(3) mitigation. Increasing the depth of incorporation by 5c m reduced NH(3) emissions by 4.4 kg ha(-1); also increasing manure coverage by incorporation reduced losses by 2 kg ha(-1) for each 10% increase in coverage, compared to surface application at 34.6 kg ha(-1). This investigation using Volt'Air yielded valuable information about simulating manure management strategies and the magnitude of their effects on NH(3) emissions.

Ammonia and nitrous oxide emissions from two acidic soils of Nova Scotia fertilised with liquid hog manure mixed with or without dicyandiamide.

Gaseous nitrogen (N) loss from field-applied manure in the form of ammonia (NH(3)) and nitrous oxide (N(2)O) has negative agronomic, environmental and health implications. This study was undertaken to evaluate the combined effect of soil type and dicyandiamide (DCD) on NH(3) and N(2)O emissions following application of liquid hog manure. Soil samples (100g) were placed in 500 mL screw-top Mason-jars and de-ionised water was added to bring the soil samples to 50%, 70% and 90% water-filled pore space (WFPS). Slurry and slurry+DCD treatments were applied at a rate of 116000 l ha(-1). The jars were then sealed and incubated at 21 degrees C for 21 d. Ammonia volatilisation was quantified using boric acid traps while N(2)O gas concentrations were analysed using gas chromatography. Results showed that DCD had no effect (p>0.05) on either NH(3) or N(2)O emissions. However, soil type had a significant effect (p<0.05) on both gases. Overall, the Pugwash soil produced 3 and 2.5 times more NH(3) and N(2)O, respectively, than the Acadia soil. N(2)O emissions from both soils increased with an increase in %WFPS, indicating that during the spring and fall in Atlantic Canada, when soils are generally wet, a significant amount of N(2)O may be emitted from these soils. The relationship between cumulative N(2)O and %WFPS was best described by an exponential function R(2)=0.83 and p<0.05 (both soils). Therefore, soil type should be taken into consideration when formulating N(2)O emission factors. The addition of DCD together with slurry may not be a viable strategy to mitigate N(2)O emissions from acidic soils. To reduce emissions of both gases, livestock slurry should not be applied on wet soils.