Short Communication: Laboratory assessment of ammonia volatilization from pig slurries applied on intact soil cores from till and no-till plots

Abstract

Aim of study: Agricultural activities are the main source of volatilized ammonia (NH3). Maximum rates are reached within a few hours after slurry application. This study aimed to evaluate the influence of soil texture, tillage and slurry dry matter (DM) on NH3 volatilization.Area of study: Mediterranean semiarid environments (NE Spain).Material and methods: Ammonia volatilization from pig slurry directly applied on the soil surface was quantified in the laboratory, in soil samples from two experimental sites with different soil textures: silty loam and sandy loam. Field treatments consisted of two tillage management practices: till by disc-harrowing or no-till. At topdressing (cereal tillering), tillage treatments were combined with slurries of different DM contents applied onto the silty loam soil. Measurements were done for two cereal cropping seasons and during the period of maximum NH3 flux (12 h after slurry application). A photoacoustic analyzer was used.Main results: Slurry spreading at sowing resulted in low volatilization (0.7-9% of NH4+-N applied) as it also did at topdressing (0.3-1.4% of NH4+-N applied). At sowing, ammonia volatilization from high DM slurry (>7.5%) was significantly enhanced by no-till in both soils. At topdressing, this result was also found in records on silty loam soil. No differences were found between tillage systems when slurry of low DM content was applied, whatever the soil texture and application moment. Although NH3 volatilization was probably affected by the laboratory conditions, the comparisons between treatments were still valuable.Research highlights: Ammonia volatilization abatement can be improved (<1 kg NH3-N ha-1) if fertilization is done after crop establishment using low DM slurries (<3.5%).

The interaction between types of cover crop residue and digestate application methods affects ammonia volatilization during maize cropping season

“…Various methods have been suggested to mitigate NH 3 loss after fertilization (Sommer et al., 2003). For example, slurry injection instead of surface broadcast has been shown to successfully reduce NH 3 volatilization (Loyon & Guiziou, 2019; Maris et al., 2020; Misselbrook et al., 2002). Yet, the European Nitrates Directive (EU Nitrates Directive, 1991), as transposed into legislation by regions in the Po Valley, still allows surface broadcast as long as slurry is distributed with low‐pressure systems and incorporated within 24–48 h. As a result, around 60% of the farms applying liquid slurry use surface broadcasting during autumn or early winter (ISTAT, 2019) due to practical reasons such as limited slurry storage, time constraints in spring, and/or field conditions (e.g., unavailability of field or of labor in spring).…”