Agriculture Reference
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(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
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