Agriculture Reference
In-Depth Information
1983; Jokela and Randall, 1997). This is probably due to the greater exposure to N applied at plant-
ing to a range of possible loss processes (immobilization, leaching, denitrification, and clay fixation)
at a time when N uptake rates are relatively low (Scharf et al., 2002). It has also been reported that
corn begins to rapidly take up N during the middle vegetative growth period, with the maximum
rate of N uptake occurring near silking (Binder et al., 2000).
Maximum AE was 35 kg of grain produced per kg N applied at the 30 kg N ha −1 level and a
minimum AE of 13 kg grain produced per kg N applied was obtained at the 210 kg N ha −1 . Overall,
AE was 23 kg grain produced per kg of N applied. Bouldin (1986) reported that in lowland rice,
the AE may range from 30 to 45 kg grain produced per kg of N applied. De Datta (1986) reported
that the AE in lowland rice varied from 21 to 46 kg kg −1 depending on source, rate, and methods
of split application. Similarly, Yoshida (1981) reported that AE in lowland rice varied from 15 to
25 kg rice grain produced per kg N applied. These results were confirmed by Prasad and De Datta
(1979). De Datta (1986) reported that the NUE is about 20% higher in temperate regions than in the
tropics. Hussain et al. (2000) also reported that AE of lowland rice in the Philippines was 18 kg of
grain produced with the application of 1.0 kg of N. Thind et al. (2010) reported that the overall AE
in lowland rice was 26 kg kg −1 .
The author studied AE in lowland and upland rice genotypes (Figures 5.1 and 5.2). There was a
significant variation among lowland and upland rice genotypes in NUE. In lowland rice, it varied
about 32-50 kg kg −1 , whereas in upland rice, the NUE varied from 10 to 28 kg kg −1 depending on
the genotypes. Fageria et al. (2007) also reported that AE efficiency varied from 16 to 23 kg kg −1
among five lowland rice genotypes, with an average value of 10 kg kg −1 . Variations in NUE among
lowland and upland rice genotypes have been reported by Fageria et  al. (2003, 2007, 2010), and
Fageria and Baligar (2005).
Novoa and Loomis (1981) reviewed the literature and reported that the AE of N for barley varied
from 7.1 to 40 kg kg −1 and for wheat it varied from 15 to 45 kg kg −1 .
60
a
50
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a
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abcd
40
de
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30
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Lowland rice genotypes
FIGURE 5.1 Agronomic efficiency of lowland rice genotypes. (From Fageria, N. K. 2014. Mineral Nutrition
of Rice. Boca Raton, Florida: CRC Press. With permission.)
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