Effect of urea management on N use efficiency of lowland transplanted rice

• Published in: Thai Agricultural Research Journal (Thailand)
• Main Authors: Sakorn Phongpan(Department of Agriculture, Bangkok (Thailand). Agricultural Chemistry Div. Nuclear Research in Agriculture Group), Jenvith Sookthongsa(Department of Agriculture, Bangkok (Thailand). Rice Research Institute. Suphan Buri Rice Experiment Station)
• Format: Journal Article
• Language: Thai
• Published: 01.09.2002
• Subjects: Ammonia; Composts; Denitrification; Losses from soil; Nitrogen cycle; Nitrogen fertilizers; Nutrient uptake; Oryza sativa; Plant nutrition; Urea; Volatilization; Yields
• ISSN: 0125-8389

Field experiment was conducted during the dry season of 1996 at the Suphan Buri rice experiment station in Central Thailand to determine the effect of urea (9.6 kg N per rai) broadcast shortly after transplanting either just pior to irrigation or following irrigation on grain yield and N use efficiency of lowland rice grown on a Phimai soil (Vertic Tropaquept) in the presence or absence of compost amendment (400 kg dry weight per rai). The results showed that N2+N2O emission was first detected with six days after urea broadcasting into floodwater. The cumulative emission of N2+N2O for both urea and urea+compost treatments represented 2.4 and 2.7 percent of applied N at 14 days following urea addition. The fertilizer N contribution to the cumulative NH3 volatilization at the end of 11 day sampling occurred 1.01 and 1.24 kg N per rai from the urea and urea+compost treatments which corresponded to 11 and 13 percent of applied N, respectively. Nitroen-15 balance data at 56 days after urea application indicated that total fertilizer N recovered by plant (shoots+roots) and soil did not differ significantly between the urea and urea+compost treatments. Losses of N (unaccounted for) from the water-soil plant system were 25 and 27 percent of N applied for the corresponding treatments, respectively. Grain yield and N uptake in both grain and straw were significantly increased with urea over the control. Compost amendment did not change grain yield and N accumulation in rice. Urea broadcasting before or after irrigation did not show any grain yield and N uptake differences, regardless of source of urea and combination with compost.