Improved acid trap methodology for determining ammonia volatilization in wind tunnel experiments

Abstract

Nitrogen loss through ammonia volatilization is an environmental and economic concern. When acid traps are used with wind tunnels to measure ammonia volatilization, loss of solution volume is observed. As the loss mechanism affects volatilization estimates, a field study was conducted to determine if solution loss from acid traps was due to either selective loss of water through evaporation, loss of bulk solution, or a combination. Two methods for calculating air flow volume through the acid traps were also examined. Solution losses from acid traps averaged 40 mL d −1 (±9.2 mL) from an initial 100 mL, and ammonium concentration increased in close accordance with the dilution-concentration relationship for aqueous solutions. Hence, solution loss was due to evaporation, with virtually no ammonium loss, confirming that the flux calculations using corrected acid trap volumes are required. Failure to correct for the reduced volumes resulted in 9%-224% overestimation of ammonium concentrations. Air flow volumes through acid traps were underestimated by 18.5% when initial and final air flow rates were used compared with continuous cumulative flow measurements. Using cumulative flows and accounting for evaporation loss from acid traps help ensure that treatment differences are not masked by the inherent variability in field-based measurements.

Ammonia volatilization, nitrous oxide emissions, and corn yields as influenced by nitrogen placement and enhanced efficiency fertilizers

“…The volume of the solution was measured before it was analyzed on the Lachat QuickChem 8500 Flow Injection Analyzer (Hach) for NH 4 + -N concentrations using a sodium salicylatebased method (QuickChem Method 12-107-06-2-A). These wind tunnels are based on designs by Lockyer (1984); details regarding win tunnel loss calculations and sampling methodology are discussed in Woodley et al (2018b). In the 2015 campaign, 1 d of sampling had to be missed because the power to the tunnels and pumps was turned off as a result heavy precipitation (97 mm) and flooding over 2 d (Supplemental Table S1).…”

World Cereal Nitrogen Use Efficiency Trends: Review and Current Knowledge

“…Ammonia volatilization is mainly governed by the concentration of the entire ammonical N (Sommer et al, 2004). Proper application technique, straw incorporation, availability of soil moisture, and avoiding application at high wind speed are some of the techniques used to reduce the rate of volatilization of the applied fertilizer N (Cao et al, 2018; Sagoo et al, 2018; Woodley et al, 2018). For instance, Cao et al (2018) reported that addition of wheat straw led to a 24% reduction in ammonia loss after the basal application.…”

Diverse rotations impact microbial processes, seasonality and overall nitrous oxide emissions from soils

“…Further, there can be long-term effects of crop rotations on SOC accumulation and the associated improvements in soil structure. For example, a long-term water quality study on the same site found that water and nitrate partitioning and loss between surface runoff and tile drainage were impacted by crop rotation (Woodley et al, 2018). Reynolds et al (2014) reported that soil physical quality including bulk density (BD) and SOC were optimal in the top 10 cm of fertilized and unfertilized corn-oatsalfalfa-alfalfa rotations, whereas CC was suboptimal in the top 10 cm as well as over the entire 0-to-50-cm profile.…”

“…Water flow from the plots is routed (via surface and subsurface catch basins) to an instrumentation building that allows tile drainage and surface runoff to be separately monitored by treatment on a continuous yearround basis for water chemistry, flow timing, and flow volume. Further detail on site design, instrumentation, and operation can be found in Drury and Tan (1995), Drury et al (2014), Reynolds et al (2014), and Woodley et al (2018).…”