Ammonia emissions after trailing hose application of digestates and cattle slurry

Summary

Anaerobic digestion (AD) is a promising technique for waste management, producing energy and contributing to nutrient recycling in agroecosystems. While digestates have higher plant-available nutrient contents, they may be prone to increased ammonia (NH3) losses due to elevated pH values and ammonium contents. This study investigates NH3 emissions from an agricultural digestate consisting of cattle slurry, solid manure and food processing waste (SLA) and a municipal organic waste digestate (LID) applied alongside untreated cattle slurry (SLU) as a reference to maize and cereals with a trailing hose. Values of dry matter, ammoniacal nitrogen (TAN) and pH were higher for SLA and LID than for SLU. Emissions were determined in five application events over three years with NH3 concentration measurements using an impinger system combined with backward Lagrangian Stochastic dispersion modeling. On average, 31%, 42%, and 43% of applied TAN volatilized as NH3 from SLU, SLA, and LID, respectively. Despite being higher from the treatments, these differences were not statistically significant. Therefore, it remains unclear whether digestates differ in NH3 emissions from untreated slurry. This topic needs further investigation due to the increasing use of AD.