See more from this Session: Nutrient Losses
Monday, November 1, 2010
Long Beach Convention Center, Exhibit Hall BC, Lower Level
The designs of laboratory systems for studying ammonia (NH3) released from fertilizers varies widely and few designs have been tested to determine accuracy and precision in measuring ammonia loss from multiple nitrogen (N) sources. A standard volatilization system design is needed for reliable and comparable studies of ammonia volatilization from nitrogen fertilizer. The objective of this study is to describe the design of a system capable of controlling air flow rate, maintaining constant humidity, and varying temperature for laboratory measurement of NH3 volatilized from N fertilizers. The system is comprised of individual chambers for soil and fertilizer, where temperature can be maintained and monitored between ambient air temperature and 30 o C, humidity is maintained at ~100%, air-flow rates can be varied, and acid traps are used to capture volatilized NH3. Two initial trials (I and II) were conducted at an N rate of 90 kg N ha-1 using air flow rates of 2.00 and 1.00 L min-1, temperature of 26° C and trapping acid volumes of 50 and 100 ml, respectively. The acid traps recovered 94.0±1.6% of lost N in trial I and 96.7±1.8% of lost N in trial II. A third trial (III) was performed using a range of N application rates (25 to 250 kg N ha-1). Measurements indicated the system accounted for 95.7±1.5% of applied N at the 25 kg N ha-1 rate and 89.3±2.3% at the 250 kg N ha-1 rate. These results indicate the system tested provides accurate and repeatable results under the conditions tested. Rapid, precise comparisons of NH3 volatilization losses from N fertilizers can be made with this system.