In Situ Measurement of Ammonia Emissions from Organic Fertilizers in Plot Experiments

Abstract

Ammonia volatilization from slurry in the field is either measured under open atmosphere from large field plots (integrated horizontal flux [IHF], mass balance) or in closed, ventilated chambers (e.g., wind tunnels), which allow the measuring of small plots but influence the climatic conditions. We conducted this study to evaluate a new method for measuring NH3 volatilization on small experimental plots under ambient climatic conditions (including rain and wind). Various pretreated cattle slurries were applied to small plots (2 by 2 m) in tillering winter wheat (Triticum aestivum L.). Ammonia collected by passive samplers on manured plots was compared with NH3 collected on standard plots, where known rates of NH3 were being released via a tubing system (standard comparison [SC] method). Forty‐five manured plots were measured simultaneously by comparison with two standard plots. The specific detection limit of this experiment was 2.5 µg NH3‐N m−2 s−1 (90 g NH3‐N ha−1 h−1). Below this value, the coefficient of variation of measured NH3 release exceeded 30%. Slurry was applied to plastic gutters on two control plots. Measured NH3 losses from these plots accounted for 78% of the absolute NH4‐N losses determined by sampling and analyzing slurry from the gutters. Measurement of the control plots was repeated during the ripening of the wheat. A strong deviation between the measurements of the two plots suggested that the accuracy of the new method is limited in dense vegetation. The results are discussed with respect to measurement accuracy and possible sources of error. A comparison with literature reports indicated that the accuracy of the SC method compared favorably to micrometeorological methods and wind‐tunnel systems.

Ammonia volatilization, nitrogen in soil, and growth of barley after application of peat manure and pig slurry

“…Thompson and Meisinger (2002) observed lower NH 3 loss from manure incorporated into moist soil than into dry soil, but excessive moisture may increase NH 3 volatilization (Sommer and Christensen 1990) if it prevents infiltration. When slurry is applied at a moderate rate to a soil with a high capacity to absorb it, differences between surface application and incorporation or injection may be small (Vandré and Kaupenjohann 1998).…”

Measuring Ammonia Concentrations and Emissions from Agricultural Land and Liquid Surfaces: A Review

“…A "standard comparison" method, 90 although unlike any of the micrometeorological methods discussed above, can be considered to be one because it is applicable to unconfined plots. Ammonia was trapped in semiopen acid traps placed 0.15-m high in the center of the plot.…”

“…Ammonia recovery in the acid trap in the wastetreated plot was multiplied by the transfer factor to obtain . 90 Whereas no meteorological measurements were required, all of the plots required a homogeneous wind field and uniformity in extent and orientation. 90 The transfer factor fluctuated erratically because of shifting wind directions and inconsistent gas flow rates.…”

“…90 Whereas no meteorological measurements were required, all of the plots required a homogeneous wind field and uniformity in extent and orientation. 90 The transfer factor fluctuated erratically because of shifting wind directions and inconsistent gas flow rates. 90 Analytical error was expected to be Ͻ25%.…”

“…90 Analytical error was expected to be Ͻ25%. 90 The method performed better in short (ϳ0.1 m) versus tall (ϳ0.6 m) wheat crop, 90 probably because of absorption of ammonia within the tall crop.…”