Madras Agric. J. 92 (10-12) : 760 - 764 October-December - 2005

760

RESEARCH NOTES

YIELD TARGETING AND INTEGRATED PLANT NUTRITION SYSTEM TO FIX CRITICAL LEVELS OF SOIL AVAILABLE N, P AND K FOR CABBAGE IN INCEPTISOLS K. SMITHA JOHN, R. SANTHI and P. MURUGESA BOOPATHI Department of Soil Science and Agricultural Chemistry, TNAU, Coimbatore - 641 003.

Fertilizer prescriptions are being developed by employing various mathematical models. Targeted yield model is the one, which is unique in the sense that it provides means for soil test based fertilizer doses and also for the computation of critical soil test values. These values are the soil test levels above which there would be no requirement of fertilizer application for indicated levels of crop yield. This would help in prescribing rationalized fertilizer doses and avoiding over or under usage of fertilizer inputs. Hence the present study was conducted during 2003-2004 in Inceptisols to fix the critical soil test values for KMnO 4-N, Olsen-P and NH4OAc-K as influenced by yield targeting and Integrated Plant Nutrition System (IPNS) for cabbage using targeted yield model. A field experiment was conducted with cabbage hybrid Questo during 2003-'04 on I -red non-calcareous sandy clay loam soil (Typic Ustropept) at farmer's holding, Chithiraichavadi, Coimbatore (11°N and 77° E; 426m elevation). The initial surface soil (0 to 15 cm) was slightly alkaline in reaction (pH 8.21), non-saline (EC. 0.42 dSm-1), low in KMnO4-N and organic carbon (205 kg ha-1 and 0. 36 % respectively), medium in Olsen-P (20.8 kg ha-1) and high in NH4OAc-K (496 kg ha-1). Before the initiation of the test crop experiment (cabbage), four fertility gradients were established following the Inductive methodology of Ramamoorthy et al. (1967). For this purpose, the field was divided into four equal strips and graded doses of fertilizers were applied to these strips viz. N0P0K0, N1/2P 1/2K1/2, N1P1K 1 and N2P 2K2 and fodder sorghum was grown as an exhaustive crop. Ni was fixed as per the general recommendation for fodder sorghum and Pi and Ki were fixed based on P and K fixing capacities of the soil. The crop was grown and cut at fodder stage.

After the harvest of the exhaustive crop of fodder sorghum and ascertaining the establishment of fertility gradient among the strips,a test crop experiment with cabbage (hybrid Questo) was conducted in rabi season. In the test crop experiment, there were twenty-four treatments with N at five levels (0,50,100,150 and 200 kgha-1), P205 at four levels (0,40, 80 and 120 kg ha-1) and K20 at three levels (0, 40 and 80 kg ha -1 ) and were superimposed randomly in such a way that all the 24 treatments were present in all the four strips on either direction. Farmyard manure (FYM) at two levels (0 and 15 t ha-1) and Azospirillum at two levels (0 and 2 kg ha-1) were applied to constitute the IPNS treatments. The IPNS treatments viz., NPK + FYM @ 15 t ha-1, NPK + FYM @ 15 t ha-1 + Azospirillum @ 2 kg ha -1 and NPK alone were superimposed across the strips. The design adopted was fractional factorial. The treatment combinations and the levels of N, P2O5 and K2O for each of the four strips are furnished in Table 1. The initial surface soil samples from all the plots were analyzed for alkaline KMnO4-N (Subbiah and Asija, 1956), Olsen-P (Olsen et al., 1954) and NH4OAC-K (Hanway and Heidal, 1952). Head and leaf yields of cabbage were recorded plot wise and these samples were analyzed for N, P and K contents (Piper, 1966) and their uptake values were computed. Making use of the data on head yield, initial soil test values (Table 2), total uptake and levels of fertilizer N, P2O5 and K2O, basic parameters viz., nutrient requirement, contribution of nutrients from soil, fertilizers, FYM and Azospirillum were calculated (Table 3) and fertilizer prescription equations were formulated based on targeted yield model (Ramamoorthy et al, 1967). Using these equations, fertilizer doses for varying soil test values (nomograms) were calculated (Table 4). The critical levels were fixed at soil test values above

YIELD TARGETING AND INTEGRATED PLANT NUTRITION SYSTEM TO FIX CRITICAL LEVELS OF SOIL AVAILABLE N, P AND K FOR CABBAGE IN INCEPTISOLS

which there is no requirement of fertilizer application (Randhawa and Velayudham, 1982). The critical level of soil available N, P and K for cabbage is furnished in Table 5. For 650 q ha-1 yield target, the critical level of NPK was 402, 68.5 and 755 kg ha-1 under NPK alone; 363, 60.5 and 658 kg ha-1 for NPK with FYM and 352, 59.8 and 652 kg ha -1 for NPK with FYM plus Azospirillum respectively. Likewise the critical levels of NPK for 700 and 750q ha-1 are also furnished (Table 5). The critical soil test values of all the three major nutrients were low under IPNS treatments (NPK plus FYM, NPK plus FYM and Azospirillum) as compared to NPK alone. This in turn resulted in saving to the tune of 34, 22 and 30 kg N, P2O5 and K2O ha-1 under NPK + FYM and 44, 24 and 32 kg N, P2O5 and K2O ha-1 under NPK + FYM + Azospirillum. Irrespective of the treatments, higher yield targeting resulted in higher critical levels of nutrients in the soil. The relatively less requirement of fertilizer N, P 2 O 5 and K 2 O under IPNS would have led to attaining the critical levels well in advance as compared to that of NPK alone. The findings of Santhi et al., (2003) supports the results of the present investigation. Thus, the results led to conclude that IPNS resulted in low critical soil test values over NPK alone and higher yield targets recorded higher critical levels for soil available NPK.

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REFERENCES Hanway, J.J. and Heidal, H. (1952). Soil Analysis methods as used in Iowa State College, Soil Testing Laboratory. Iowa State College Agric. Bull., 57: 1-13. Olsen, S.R., Cole, C.V., Watanabe, F.S. and Dean, L. (1954). Estimation of available phosphorus in soils by extraction with sodium bicarbonate. U.S.D.A. Circ. 939. U.S. Govt. Printing Office, Washington DC. Piper, C S. (1966). Soil and Plant Analysis. Hans Publications, Bombay. Ramamoorthy, B., Narasimhan, R.L. and Dinesh, R.S. (1967). Fertilizer application for specific yield targets of Sonora 64 (wheat). Indian Fmg. 17 : 43-45. Randhawa, N.S. and Velayutham, M. (1982). Research and development programmes for soil testing in India. Fert. News, 27 : 35 - 64. Santhi, R., Natesan, R and Selvakumari, G. (2003). Critical levels of soil available N, P and K for cabbage as influenced by yield targeting under integrated plant nutrition system on Inceptisols. Madras Agric. J., 90 (7-9) : 539540. Subbiah, B.V. and Asija, G.L. (1956). A rapid procedure for estimation of available nitrogen in soils. Curr. Sci. 25 : 259-260.

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SMITHA JOHN, K R. SANTHI and P. MURUGESA BOOPATHI

Table 1. Treatment structure of test crop experiment S. No. Treatment combinations

Levels of nutrients (kg ha")

N

P2O5

K2O

N

P2O5

K2O

1.

0

0

0

0

0

0

2.

0

0

0

0

0

0

3.

0

0

0

0

0

0

4.

0

0

0

0

0

0

5.

1

0

0

50

0

0

6.

1

1

0

50

40

0

7.

1

1

1

50

40

40

8.

2

0

0

100

0

0

9.

2

0

1

100

0

40

10.

2

1

0

100

40

0

11.

2

1

1

100

40

40

12.

2

2

0

100

80

0

13. '

2

2

1

100

80

40

14.

2

2

2

100

80

80

15.

3

0

0

150

0

0

16.

3

1

1

150

40

40

17.

3

2

2

150

80

80

18.

3

3

0

150

120

0

19.

3

3

1

150

120

40

20.

3

3

2

150

120

80

21.

4

2

1

200

80

40

22.

4

2

2

200

80

80

23.

4

3

1

200

120

40

24.

4

3

2

200

120

80

Levels of FYM, Azospirillum and fertilizer nutrients Level 0 1 2 3 4

FYM (t ha-1) 0 15 -

Azospirillum (kg ha-1) 0 2 -

N (kg ha-1) 0 50 100 150 200

P2O5 (kg ha-1) 0 40 80 120 -

K2O (kg ha-1) 0 40 80 -

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YIELD TARGETING AND INTEGRATED PLANT NUTRITION SYSTEM TO FIX CRITICAL LEVELS OF SOIL AVAILABLE N, P AND K FOR CABBAGE IN INCEPTISOLS

Table 2. Range and mean values of initial soil available nutrients and yield of cabbage Parameter

Range (strip I to strip IV )

Mean

KMnO4-N

190-277

234

Olsen - P

18.1-63.6

40.0

NH4OAc-K

448 - 622

535

KMnO4-N

216- 261

246

Olsen - P

36.8 - 52.6

47.3

521 - 571

554

Control plot

21000-30365

25682

Treated plots

26484 - 77210

51847

-1

Initial Soil test values (kg ha )

Post-harvest Soil test values (kg ha-1)

NH4OAc-K -1

Head yield (kg ha )

Table 3. Nutrient requirement, percent contribution from soil and fertilizer nutrients for cabbage Parameters N

Basic data P2O5

K2O

Nutrient requirement (kg q )

0.28

45.71

51.08

Per cent contribution from soil

0.13

53.10

44.19

Per cent contribution from fertilizers

0.29

20.28

79.59

Per cent contribution from FYM (CFYM)

30.20

38.80

35.30

Per cent contribution from Azospirilhim

38.70

44.90

46.70

-1

(C FYM+AZO)

764

SMITHA JOHN, K R. SANTHI and P. MURUGESA BOOPATHI

Table 4. Estimates of fertilizer doses for 700 q ha-1 head yield target of cabbage Soil test values (kg ha-1)

NPK (kg ha-1)

IPNS NPK+FYM (kg ha-1)

200

207

173

163

240

171

137

127

280

136

102

92

10

176

154

152

14

165

143

141

18

154

132

130

300

159

129

127

400

128

98

96

500

97

67

65

NPK+FYM+ Azospirilhim (kg ha-1)

Nitrogen

Phosphorus

Potassium

Table 5. Critical levels of soil test values for cabbage as influenced by yield targeting under IPNS (kg ha1) S. Treatments No.

N

650 (q ha-1) P K

N

700 (q ha-1) P

K

N

750 (q ha-1) P

K

1.

NPK alone

402

68.5

755

433

73.8

813

464

79.1

871

2.

NPK+FYM

363

60.5

658

394

65.8

719

425

71.1

774

3.

NPK+FYM+ Azospirillum

352

59.8

652

383

65.1

710

414

70.4

768