Effect of Covering Deep Litter Stockpiles on Methane and Ammonia Emissions Analyzed by an Inverse Dispersion Method

Ammonia (NH3) and methane (CH4) emission rates from cattle deep litter and horse manure deep litter in farm-scale stockpiles were measured using an inverse dispersion method based on the backward Lagrangian Stochastic (bLS) model. The aims of the study were to (i) evaluate the effects of timing and carefulness of covering a stockpile, (ii) measure emissions from handling and storing deep litter, (iii) compare emissions from manure stored in a container and stockpile, (iv) determine emissions from cattle and horse manure deep litter, and (v) evaluate potential effects of pile temperature on emissions. New emission data with relatively high temporal resolution are provided. High variability in CH4 emissions was observed with no clear effects on the timing of covering, even though the temperatures inside the piles were different. NH3 emissions occur immediately after pile establishment and the emissions were highly influenced by the timing of covering. In the first week of storage, covering reduced NH3 emissions by 92 +/- 9% when comparing the emissions from a noncovered and totally covered stockpile. This demonstrates the effect of applying a cover immediately to avoid NH3 emissions. The long-term effects of covering strategies as well as the influence of temperature and season are also discussed. For horse manure deep litter, storage in a closed (covered) container instead of a covered stockpile was observed to reduce CH4 emissions by 50 +/- 58% and NH3 emissions by 67 +/- 37%.