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Title: Nitrogen source effects on ammonia volatilization as measured with semi-static chamber

item JANTALIA, CLAUDIA - Embrapa National Research Center
item Halvorson, Ardell
item Follett, Ronald
item ALVES, BRUNO - Embrapa National Research Center
item POLIDORO, JOSE - Embrapa National Research Center
item URQUIAGA, SEGUNDO - Embrapa National Research Center

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2012
Publication Date: 9/5/2012
Citation: Jantalia, C.P., Halvorson, A.D., Follett, R.F., Alves, B.R., Polidoro, J.C., Urquiaga, S. 2012. Nitrogen source effects on ammonia volatilization as measured with semi-static chamber. Agronomy Journal. Vol. 104:1595-1603.

Interpretive Summary: Ammonia volatilization loss resulting from nitrogen (N) fertilizer application to agricultural soils is a major concern in crop production system. Measuring ammonia loss in small plot N studies can be very difficult and expensive. The objective of our study was to examine the use of two inexpensive semi-static chambers (semi-open and open) in measuring ammonia volatilization from N fertility plots under irrigated corn production on a high pH soil. The open chamber is a relatively new technique that was compared to the semi-open chamber which has been previously used in small plot research, but with the use of soil anchors. In this study, soil anchors were not used to support the chambers. Labeled N urea fertilizer was used to calibrate the chambers for ammonia capture under our field conditions. The calibration data were used to estimate ammonia loss from several N sources applied to field plots. Both chambers without soil anchors, worked well under our small field plot conditions for determining ammonia loss. Ammonia losses from the N fertilizer sources applied to our system ranged from 0.1 to 3.6%. The low ammonia loss level probably resulted due to the application of 19 mm of irrigation water the day after N application. The open chamber method is a viable, inexpensive method for estimating ammonia loss in small field plot studies.

Technical Abstract: Ammonia (NH3) volatilization is one of the main pathways of nitrogen (N) loss from agricultural cropping systems. This study evaluated the NH3-N loss from four urea based N sources [urea, urea-ammonium nitrate (UAN), SuperU, and ESN] surface band applied at a rate of 200 kg N ha-1 to irrigated, strip-till corn production systems for 2 yr using semi-static chambers (semi-open and open) to measure NH3-N loss. The efficiency of the semi-static chambers in estimating NH3-N loss under field conditions was determined using 15N labeled urea applied at rates of 50, 100, and 200 kg N ha-1. Both chamber types had similar NH3-N recoveries and calibration factors. Immediate irrigation with 16-19 mm of water one day after N fertilization probably limited NH3-N volatilization from surface applied N fertilizers to a range of 0.1-4.0% of total N applied. SuperU, which contains a urease inhibitor, had the lowest level of NH3-N loss when compared to the other N sources. Analyzed across years, estimated NH3-N losses for the N sources were in the order: ESN=UAN>urea>SuperU. Both years the results showed that measurement time may need to be increased to evaluate NH3-N volatilization from polymer-coated urea N sources such as ESN. The open-chamber method was a viable, low cost method for estimating NH3–N loss from small field plot N studies.