Agriculture Reference
In-Depth Information
BRA 02601
300 mg N kg
-1
0
FIGURE 6.3
Root growth of upland rice genotype BRA 02601 at two N levels.
received only N but no P. In rice, NUE increased 14% with the addition of P together with N com-
pared to N alone. In sunflower and field pea, NUE increased 59% and 46%, respectively, with the
addition of P and N together compared to N addition alone. These results clearly showed the positive
influence of the balanced supply of N and P in improving NUE in crop plants.
For nonirrigated crops, better root growth as a result of adequate P supply could enable the
plants to absorb water from deeper soil layers during droughty spells, thereby increasing NUE as
well (Aulakh and Malhi, 2005). In addition, when N is provided as an ammonium or ammonium-
producing fertilizer, the acidifying effect could enhance N concentration in plants (Malhi et al.,
1988) and P solubility in soil (Prasad and Power, 1997), thus providing a positive interaction.
However, in those few soils that tested high in available N and P, the addition of single or both
element fertilizers may not provide a grain yield advantage, regardless of the type of the crop,
fertilizer, or placement method (Buah et al., 2000). Aulakh and Malhi (2005) concluded that, in
a situation where a farmer cannot afford to apply both N and P in optimum amounts, it is better
TABLE 6.4
Influence of Nitrogen × P Interaction on NUE in Principal Field Crops
NUE (kg Grain kg
−1
N)
Reference
Crop Species
Without N
With N + P
Corn
8.8
11.5
Singh (1991)
Corn
32.4
40.0
Satyanarayan et al. (1978)
Wheat
20.3
25.9
Dwivedi et al. (2003)
Rice
22.4
25.5
Dwivedi et al. (2003)
Sunflower
8.7
13.8
Aulakh and Pasricha
(1990)
Field peas
10.3
15.0
Pasricha et al. (1987)
Source:
Adapted form Aulakh, M. S., N. S. Pasricha, and A. S. Azad. 1990.
Soil Sci
. 150:705-709; Dwivedi, B. S. et al.
2003.
Field Crops Res
. 80:167-193; Pasricha, N. S. et al. 1987. In:
Research Bulletin
15, p. 92. Department of
Soils, Ludhiana, India: Punjab Agricultural University; Satyanarayana, T., V. P. Badanur, and G. V. Havanagi.
1978.
Indian J. Agron
. 23:49-51; Singh, A. K. 1991.
Indian J. Agron
. 36:508-510.
