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Yield and Protein Content of Rice as Affected by Rate, Source, Method, and Time of Applied N 1
Author(s) -
Allen S. E.,
Terman G. L.
Publication year - 1978
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1978.00021962007000020007x
Subject(s) - sowing , straw , urea , yield (engineering) , agronomy , oryza sativa , ammonium sulfate , chemistry , ammonium , nitrogen , zoology , grain yield , biology , materials science , biochemistry , organic chemistry , chromatography , gene , metallurgy
Published results suggest that low rates of applied N may have been responsible for low yields and grain protein of rice ( Oryza sativa L.) grown in pot experiments. A series of greenhouse pot experiments was, therefore, conducted at Muscle Shoals, Ala., with rice grown under continuous flooding on Sango sicl (Ochrepic Fragiudult, 5 kg/pot) to study effects of rate and source of applied N (up to 5.0 g/pot) on yield, N recovery, and grain protein. Uniform high rates of other nutrients were applied. Urea or ammonium sulfate mixed with the soil before planting markedly increased yield of both grain and straw, but NO 3 ‐N was largely lost by denitrification. Rates of 0.5 to 1.0 g of non‐NO 3 ‐N were required for early growth and tillering, factors which were well correlated with grain yield at maturity. Urea and ammonium sulfate topdressed in the floodwater after tillering were more effective than NO 3 ‐N and increased yield of grain proportionately more than straw, as compared to application of all N prior to planting. Grain and straw yields increased curvilinearly with higher N rates, but uptake of N was highly rectilinear with all rates of applied N. Grain protein also increased with rate of N (from 7 to 3% with no N to 9 to 12% with 2 to 5 g of N/pot). Thus, adequate rates and timing of applied N increased both yield and protein content of grain in these pot experiments (without lodging being a problem). These responses varied among sources, methods and time of application, and cultivars; but maximum yield was invariably obtained from rates of N much higher than commonly reported for pot experiments.