Nitrogen Use Efficiency in Crop Plants - Nitrogen Management in Crop Production - page 224

TABLE 5.3
Physiological Efficiency of Lowland Rice under Different N Levels

Nitrogen Rate (kg ha −1 ) Physiological Efficiency (kg kg − 1 )

30 156

60 166

90 182

120 132

150 146

180 126

210 113

Average 146

0.62 **

R 2

Source: Adapted from Fageria, N. K. and V. C. Baligar. 2001. Commun. Soil Sci. Plant
Anal. 32:1405-1429.
**Significant at the 5% probability level.

where GY f is the grain yield of the fertilized plot, GYf uf is the grain yield of the unfertilized plot, N uf
is the N uptake of the fertilized plot (grain plus straw), and N uuf is the N uptake of the unfertilized
plot (grain plus straw).
Fageria and Baligar (2001) determined the APE of lowland rice under variable N levels (Table 5.4).
The APE varied from 46 to 75 kg kg −1 , with an average value of 63 kg kg −1 . The APE was sig-
nificantly influenced by N levels and the variation was 87% with the addition of N in the range of
30-210 kg ha −1 . Fageria et al. (2007) reported that APE among five lowland rice genotypes varied
from 56 to 123 kg kg −1 , with an average value of 77 kg kg −1 . The Average APE (average of two loca-
tions and various N levels) in lowland rice reported by Thind et al. (2010) was 42 kg kg −1 . Gerik
et al. (1994) reported that cotton requires 16-20 kg of N per 100 kg of lint. This translates into
NUEs of 5.0-6.6 kg of lint per kg of N uptake.

TABLE 5.4
Agrophysiological Efficiency of Lowland Rice under Different N Levels

Nitrogen Rate (kg ha −1 ) Agronomic Efficiency (kg kg − 1 )

30 72

60 73

90 75

120 66

150 57

180 51

210 46

Average 63

0.87 **

R 2

Source: Adapted from Fageria, N. K. and V. C. Baligar. 2001. Commun. Soil Sci. Plant Anal .
32:1405-1429.
**Significant at the 5% probability level.