Fertility status:

Soil fertility refers to the inherent capacity of the soil to supply nutrients in adequate amounts and in suitable proportions for crop growth and crop yield. The trend in increasing the yield by adopting high yielding varieties has resulted in   deficiency of nutrients in soils and has reflected as deficiency symptoms in plants. Hence, it is required to know the fertility (NPK) status of the soils of the State for applying the required dosage of fertilisers and planning the regional distribution of fertilisers. For this purpose, the soil samples collected from grid points (1906 grids) all over the state were analysed for pH, Ec., organic carbon, available phosphorus and potassium.

Available nitrogen status:

The available nitrogen status presented show that about 10.3 per cent of the soils in the state fall under the low category, 35.8 per cent under medium and 53.9 per cent under high category. The areas covering Western ghats, coastal plains and Malnad areas of the State, under forest and plantations, are high in nitrogen. Apart from this  areas under irrigation and hilly regions of the plateau are high to medium in nitrogen. Rest of the area of the state is low in nitrogen.

Class

Available

Area

N (Kg/ha)

‘000 ha.

Per cent.

Low

< 280

1963.8

10.31

Medium

280 - 560

6827.8

35.84

High

> 560

10258.2

53.85

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Available phosphorus status:

The available phosphorus status in the soils of Karnataka reveals that about 83 per cent of the soils in the state are low in phosphorus. About 17 per cent area is under medium category implying thereby that most of the soils need to be fertilised through phosphorus for sustained production.

 Class

Available

Area

N (Kg/ha)

‘000 ha.

Per cent.

Low

< 10

15799.6

82.93

Medium

10 - 25

3250.2

17.07

High

> 25

-

-

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Available potassium status:

The  potassium status in the soil of the State shows that   potassium is medium to high in most of the soils of the state except in laterite soils of Coastal Plains and Western Ghats and in  shallow red and black soils, where it is low.

Class

Potassium

Area

(Kg/ha)

‘000 ha.

Per cent.

Low

< 118

2066.2

10.85

Medium

< 118 - 280

7032.6

36.91

High

> 280

19951.0

52.24

Micronutrient status:

In recent times emphasis is given on soil micronutrient sufficiency /deficiency and are being intensively studied because of wide spread deficiencies in soils leading to reduced crop yields. The deficiencies are caused due to use of chemically pure and micronutrient free fertilisers, cultivation of improved crop varieties with high nutrient requirements and intensive cultivation of crops. Soil samples were analysed for zinc, iron, maganese and copper through standard methods.

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Available zinc status:

The available zinc status indicates that about 79 per cent area of soils in the state have zinc deficiency. Zinc fertilisation is deinitely required for sustained crop production.

Class

Zinc

Area

(ppm)

‘000 ha.

Per cent.

Sufficient

0.5 - 1.2

3974

20.8

Deficient

-

15071

79.2

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Available iron status:

The available iron status reveals that about 34 per cent of the soils in the state are deficient in iron which need corrective measures for increased crop production.

Class

Iron

(ppm)

Area

‘000 ha.

Per cent.

Sufficient

12570

66.00

(non-calcareous soils)

> 3.7

(calcareous soils)

> 6.3

Deficient

6475

34.00

(non-calcareous soils)

< 3.7

(calcareous soils)

< 6.3

 

NIC-AGRI