On-Farm Comparison of Two Dairy Manure Application Methods in Terms of Ammoniaand Odor Emissions and Costs

Abstract

Abstract. Ammonia and odor emissions from land application of liquid dairy manure, and costs associated with manure land application methods, are serious concerns for dairy owners, regulators, academic, and the general public. Odor and ammonia samples from agricultural fields receiving liquid dairy manure applied by surface broadcast and direct manure injection methods were collected using Tedlar ® bags and passive ammonia samplers. The collected odor and ammonia samplers were analyzed using a dynamic forced-choice olfactometer and a flow-injection analysis system, respectively. Costs associated with both of the manure application methods were estimated. The test results showed a 68% reduction in ammonia emissions with direct manure injection versus surface broadcast over a two-day period across two fields. Olfactometry results showed direct manure injection reduced odor emission by 33% compared with surface broadcast; therefore, applying liquid dairy manure by direct manure injection could be recommended for Idaho dairy industry as one best management practice to manage ammonia and odor emissions. The estimated costs associated with surface broadcast were lower than direct manure injection. Further studies evaluating both the manure application costs and agronomic benefits of retained manure N fertilizer under Idaho soil and climate conditions are warranted to determine which manure application method is more economically viable.