Agriculture Reference
In-Depth Information
(NH
4
)
2
SO
4
(Y) = 2.8383 + 0.0079X - 0.0000092X
2
5
R
2
= 0.7365**
4
3
2
CO(NH
2
)
2
(Y) =1.9544 + 0.02003X - 0.0000401X
2
R
2
= 0.5165**
1
0
50
100
150
200
250
300
350
400
Nitrogen application rate (mg kg
-1
)
FIGURE 8.14
Number of panicles of upland rice as influenced by two nitrogen sources. (From Fageria, N.
K., A. Moreira, and A. M. Coelho. 2011b.
J. Plant Nutr
. 34:361-370. With permission.)
(NH
4
)
2
SO
4
(Y) = 76.7805 + 0.3651X - 0.000701X
2
R
2
= 0.4826**
120
100
CO(NH
2
)
2
(Y) = 92.7142 + 0.1859X - 0.00036X
2
R
2
= 0.8595**
80
60
40
20
0
50
100
150
200
250
300
350
400
Nitrogen application rate (mg kg
-1
)
FIGURE 8.15
Plant height of upland rice as influenced by two nitrogen sources. (From Fageria, N. K., A.
Moreira, and A. M. Coelho. 2011b.
J. Plant Nutr
. 34:361-370. With permission.)
rates, ammonium sulfate produced higher grain yield compared to urea. However, at the interme-
diate N rate (125-275 mg N kg
−1
), urea was slightly superior in producing grain yield compared
to ammonium sulfate. Across the six N rates, ammonium sulfate produced a 12% higher grain
yield compared to urea. The superiority of ammonium sulfate at higher N rates compared to urea
may be associated with the higher acidity-producing capacity of ammonium sulfate compared