Impact on agricultural growth the case of India

Table 2.2 provides a synopsis of more detailed evidence of the size of India's groundwater economy, which is more explicitly described in DebRoy and Shah (2003).4 In short, a regression equation was fit to cross-section data for 273 districts in which the dependent variable was the average value of gross farm output per hectare; and independent variables were average fertilizer use per hectare, percent of net sown area under surface irrigation and percent of net sown area under groundwater irrigation. Regressions were estimated for 1970-1973 and 1990-1993 data-sets. These showed that adding a hectare under groundwater irrigation made smaller contribution to increasing average value of output per hectare compared with adding a hectare under canal irrigation because farmers in South Asian canal commands are doubly blessed: they use cheap canal water to cut irrigation costs and costly groundwater to give their crops 'irrigation-on-demand'. However, the increase in groundwater irrigated area in an average Indian district after 1970 has been so large that groundwater irrigation contributed much more to increased value of agricultural output per hectare compared with surface irrigation. Table 2.3 summarizes the results; it shows that in the scenario of growing productivity of farmland, the contribution of surface

Table 2.2. Contribution of surface water irrigated and ground water irrigated area to total agricultural output, all India: 1970-1973 and 1990-1993. (From DebRoy and Shah, 2003.)

Year/indicators

(at 1990 dollar/rupee exchange rate) 1970-1973 1990-1993 Change (%)

Table 2.2. Contribution of surface water irrigated and ground water irrigated area to total agricultural output, all India: 1970-1973 and 1990-1993. (From DebRoy and Shah, 2003.)

Average agricultural productivity ($/ha)

261.4

470.3

79.9

Contribution of SW ($/ha)

41.3

62.6

51.6

Contribution of GW ($/ha)

13.3

74.0

456.4

Contribution of SW (million $)

4,680

7,005

49.7

Contribution of GW (million $)

1,320

7,297

452.8

Contribution of SW as percent of total

15.5

13.9

-1.6%

agricultural output

Contribution of GW as percent of total

4.4

14.5

+10.1%

agricultural output

Total agricultural output/year (million $)

28,282

49,891

76.4

Table 2.3. Groundwater use per hectare in South Asia. (From IWMI survey of 2629 farmers in 2002.)

Horse

Estimated average

power

Total crop water

application of irrigation

hours

requirements (m3)*

water by sample farmers

Wheat

656

4,000

1,476.00 (36.9)

Kharif paddy

1,633

12,000

3,674.25 (30.6)

Boro paddy

3,266

18,000

7,348.50 (40.8)

Oilseeds

81 6

5,500

1,836.00 (33.4)

Coarse cereals

811

5,000

1,824.75 (36.5)

*Michael 2001

*Michael 2001

irrigation to aggregate farm output increased by 50% over 1973-1993, but that of groundwater irrigation soared by 450% over the same period. Interestingly, at $7.3 billion, groundwater contribution to agricultural output is close to $8 billion, which is our rough estimate of the economic value of groundwater irrigation in India in Table 2.2. To place this number in perspective, it is useful to note that this contribution of groundwater development to annual farm output in India is four times the annual public investment in irrigation projects, and more than all expenditures incurred by governments in India on poverty alleviation and rural development programmes.

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