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United States Department of Agriculture

Agricultural Research Service

Research Project: Agrochemical and Weed Seed Fate and Transport in Mid-South Crop Production Systems

Location: Crop Production Systems Research Unit

Title: Nitrogen sources and timing effects on nitrogen loss and uptake in delayed flood rice

Authors
item Dillon, K -
item Walker, T -
item Harrell, D -
item Krutz, Larry
item Varco, J -
item Koger, C -
item Cox, M -

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 17, 2012
Publication Date: February 2, 2012
Citation: Dillon, K.A., Walker, T.W., Harrell, D.L., Krutz, L.J., Varco, J.J., Koger, C.H., Cox, M.S. 2012. Nitrogen sources and timing effects on nitrogen loss and uptake in delayed flood rice. Agronomy Journal. 104:466-470.

Interpretive Summary: Collaborative studies among USDA-ARS, Mississippi State and Louisiana State University scientist were conducted from 2009 through 2010 in the rice (Oryza sativa L.) producing regions of Louisiana and Mississippi to evaluate ammonia volatilization loss and subsequent effects on apparent N recovery efficiency (ANRE) and grain yield. Nitrogen application 10 days before flooding resulted in the least grain yield and yields tended to increase with fewer days between application and permanent flood establishment. In the Louisiana environment, urea + NBPT, and urea + NBPT + DCD resulted in yields greater than urea alone. Our results indicate that if rice growers cannot establish floods within a few days after urea application, NBPT should be included with the urea application to minimize volatilization loss, improve fertilizer efficiency and protect yield potential.

Technical Abstract: Experiments were conducted over four environments during 2009 and 2010 in the rice (Oryza sativa L.) producing regions of Louisiana and Mississippi to evaluate ammonia volatilization loss and subsequent effects on apparent N recovery efficiency (ANRE) and grain yield. Multiple N sources were applied 10, 7, 4, and 1 day(s) before flood (dbf) at the rate of 168 kg N ha-1. Cumulative ammonia volatilization losses for urea for the two Louisiana environments were 19.45 and 32.93% compared to 6.78 and 6.96% for Mississippi. Urea + NBPT, Urea + NBPT + DCD, and AS all minimized volatilization losses over all environments (range of 1.85 to 4.91%). Additionally, modeled volatilization data demonstrated that Urea + NBPT and Urea + NBPT + DCD slowed the rate of loss (7.2 to 7.7 d) relative to the urea, AS, and UAS blend (3.6 d). Apparent N recovery efficiency ranged from 43 to 71% which is in the ranges published for delayed-flood rice. In two of the three environments, grain yield was influenced by application time. Nitrogen application 10 dbf resulted in the least grain yield and yields tended to increase with fewer days between application and permanent flood establishment. In the Louisiana environment, urea + NBPT, and urea + NBPT + DCD resulted in yields greater than urea alone. If growers cannot establish floods within a few days after urea application, NBPT should be included with the urea application to minimize volatilization loss and protect yield potential.

Last Modified: 7/25/2014
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