Design and Test of a Field Sampler for Ammonia Volatilization1
- D. E. Kissel,
- H. L. Brewer and
- G. F. Arkin2
A system is needed to measure ammonia volatilization from N fertilizer applied under field conditions. This study was undertaken to develop a device for making these measurements and still maintain a field environment. The basic system developed consists of a vacuum pump, a chemical trap to capture ammonia, and the volatilization chamber.
The volatilization chamber consists of a steel cylinder 21.8-cm I.D. by 15-cm long that is forced into the soil with its top flush with the soil surface to provide a microplot. The lid assembly attached to the cylinder includes a hinge and reversible electric motor that allows the lid to be automatically rotated from the microplot. The volatilization chamber was designed with the removable lid so that the lid is closed only for short intervals during the day while ammonia loss is measured. The total ammonia loss is calculated by integrating the rates of loss over time. Between measurements, the lid is open to allow normal environmental conditions of temperature, wind movement, etc., on the micro-plot. The volatilization chamber has five air intake ports and one exhaust port. Ammonia loss was unaffected by air flow rate if air movement through the chamber exceeded 15 exchange volumes/min.
Our complete system consisted of eight volatilization chambers with a system of multiple chemical traps that can operate automatically without attention for 24 hours. When tested in the field, duplicate measurements of ammonia loss from ammonium sulfate agreed quite closely, both in the rates of loss and the total ammonia loss. In another test, ammonia loss from ammonium chloride agreed reasonably well with other laboratory results.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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