Agriculture Reference
In-Depth Information
Ammonium sulfate (Y) = 13.6034 + 0.10065X - 0.00030X
2
R
2
= 0.9042**
Urea (Y) = 13.8705 + 0.05489X - 0.00018X
2
R
2
= 0.7777**
25
20
Ammonium sulfate
15
Urea
10
5
0
100
200
300
400
Nitrogen application rate (mg kg
-1
)
FIGURE 8.10
Relationship between nitrogen rate applied by ammonium sulfate and urea and grain yield of
lowland rice. (From Fageria, N. K., A. B. Santos, and A. M. Coelho. 2011c.
J. Plant Nutr
. 34:371-386. With
permission.)
Similarly, Fageria et al. (2011c) studied the influence of ammonium sulfate and urea fertilization
on the panicle number of lowland rice (Figure 8.11). The number of panicles increased significantly
and quadratically with increasing N rates from 0 to 400 mg kg
−1
of soil by both ammonium sul-
fate and urea sources of N (Figure 8.11). Panicle response to N fertilization was similar for both
the N sources; however, the magnitude of response was higher in the case of ammonium sulfate.
10
Ammonium sulfate
8
Urea
6
Ammonium sulfate (Y) = 6.1986 + 0.0233X - 0.000041X
2
R
2
= 0.7017**
Urea (Y) = 5.6115 + 0.0224X - 0.000041X
2
R
2
= 0.5651**
4
2
0
100
200
300
400
Nitrogen application rate (mg kg
-1
)
FIGURE 8.11
Relationship between nitrogen rate applied by ammonium sulfate and urea and panicle num-
ber of lowland rice. (From Fageria, N. K., A. B. Santos, and A. M. Coelho. 2011c.
J. Plant Nutr
. 34:371-386.
With permission.)
