Effect of encapsulated calcium carbide and urea application methods on denitrification and N loss from flooded rice |
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Authors: | D G Keerthisinghe Lin Xin-Jian Luo Qi-xiang and A R Mosier |
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Affiliation: | (1) Division of Plant Industry, CSIRO, G.P.O. Box 1600, 2601 Canberra, A.C.T., Australia;(2) Fujian Academy of Agricultural Sciences, Fuzhou, Fujian Province, People's Republic of China;(3) Crop Cultivation and Tillage Institute, Jiangxi Academy of Agricultural Sciences, Nanchang, Jiangxi Province, People's Republic of China;(4) United States Department of Agriculture, Agricultural Research Service, P.O.Box E, 80522 Fort Collins, CO, USA |
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Abstract: | Poor N fertilizer use efficiency by flooded rice is caused by gaseous losses of N. Improved fertilizer management and use of nitrification inhibitors may reduce N losses. A microplot study using15N-labelled urea was conducted to investigate the effects of fertilizer application method (urea broadcast, incorporated, deep-placed) and nitrification inhibitor encapsulated calcium carbide (ECC)] treatments on emission of N2+N20 and total loss of applied N on a grey clay near Griffith, NSW, Australia. Both incorporation and deep placement of urea decreased N2+N2O emission compared to urea broadcast into the floodwater. Addition of ECC significantly (P < 0.05) reduced emission of N2+N20 from incorporated or deep-placed urea and resulted in increased exchangeable ammonium concentrations in the soil in both treatments. Fifty percent of the applied N was lost when urea was broadcast into the floodwater. Total N loss from the applied N was significantly (P < 0.05) reduced when urea was either incorporated or deep placed. In the presence of ECC the losses were reduced further and the lowest loss (34.2% of the applied N) was noted when urea was deep-placed with ECC. |
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Keywords: | nitrification denitrification 15N balance nitrogen loss |
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