FRAME strategy for addressing excess N use in rice to enhance farm profitability and to reduce GHGs

A.J. McDonald (ajm9@cornell.edu), S.Sherpa (s.sherpa@cgiar.org)

Kisan yield level (kg/ha)¹

Rice crop N content (kg/ha)²

Total N rate - upper limit (kg/ha)³

DAP (kg/ha)⁴

Urea (kg/ha)

DAP (kg/acre)

Urea (kg/acre)

DAP (kg/kattha)

Urea (kg/kattha)

1500

36

66

21

135

9

55

0.27

1.71

1750

42

72

25

147

10

59

0.31

1.86

2000

48

78

28

158

12

64

0.36

2.00

2250

54

84

32

170

13

69

0.40

2.15

2500

60

90

36

182

14

74

0.45

2.30

2750

66

96

39

193

16

78

0.49

2.45

3000

72

102

43

205

17

83

0.54

2.59

3250

78

108

46

217

19

88

0.58

2.74

3500

84

114

50

228

20

92

0.63

2.89

3750

90

120

53

240

22

97

0.67

3.04

4000

96

126

57

252

23

102

0.72

3.18

4250

102

132

60

263

24

107

0.76

3.33

4500

108

138

64

275

26

111

0.81

3.48

4750

114

144

68

287

27

116

0.85

3.63

5000

120

150

71

298

29

121

0.90

3.77

5250

126

156

75

310

30

125

0.94

3.92

5500

132

162

78

322

32

130

0.99

4.07

5750

138

168

82

333

33

135

1.03

4.22

6000

144

174

85

345

35

140

1.08

4.36

6250

150

180

89

357

36

144

1.12

4.51

6500

156

186

92

368

37

149

1.17

4.66

6750

162

192

96

380

39

154

1.21

4.81

7000

168

198

100

391

40

158

1.26

4.95

Notes

¹ Maximum farmer yield level achieved in the last three years

² Estimated N content in rice plant to support maximum achieved yield (above-ground DM estimated by assuming a HI of 50% and 20% MC);  assumes an N concentration of 1.5% concentration in dry matter per IRRI knowledge bank

³ Upper limit for N application with an N-balance target of + 30 kg/ha with N inputs based solely on inorganic fertilizer and outputs estimated for grain and straw w/ complete removal

⁴ DAP rate determined by crop P requirement at full replacement levels for crop removal;  assumes a P2O5 concentration of 0.64% in rice above-ground dry matter per IRRI knowledge bank

Key messages:

If farmers are applying more N than the upper limit for their maximum achieved yield level, reductions in N rate are possible without reducing yields. These farmer should be encouraged to reduce their N usage to the corresponding upper limit rate. 

If farmers are applying less N than the upper limit for their maximum achieved yield level, they should maintain their current rate unless they are interested in increasing yields.  For famers who wish to increase yields, they can be encouraged to experiment with a moderately higher N rate (i.e. add an additional 25 kg/ha) to determine if there is a yield gain that can be achieved with additional N.