36 presidential address section a. 



Irrigation by Pumping. 



The question of pumping- water for irrig-ation has been 

 discussed on many occasions, and I wish once ag-ain to state 

 that irrigation by pumping will pay in every case where the 

 higher-priced crops can be grown. Take lucerne (alfalfa) as an 

 example. The quantity of water required per acre crop may be 

 taken at about 100,000 gallons, which is about a 4^-inch water- 

 ing. A ton of dried hay can be obtained per acre crop, and 

 at 5s. per 100 lbs. the return will be £5. The revenue for 

 six crops each year will therefore be £30, and after deducting, 

 say, £15 for working expenses, such as harvesting, transport, 

 railage, marketing, etc., there is a balance of £15, or £2 los. per 

 crop. 



Water can be raised at less than id. per 1,000 gallons for 

 lifts of under 100 ft. by well-designed pumpitig ])lants; so, 

 taking 600,000 gallons as the quantity of water required for 

 six crops, the cost at id. per 1,000 gallons will be £2 ids., 

 or 8s. 4d. per acre crop. This leaves a profit of £2 is. 8d. 

 per acre crop, or £12 los. per acre annum. -Land under such 

 conditions, which is worth about £4 to £8 per acre before being 

 irrigated, is often worth from £100 to £180 per acre when 

 planted with lucerne or first-class citrus trees of five years' 

 growth. 



Existing Irrigation Schemes. 



The existing storage and gravitation schemes above the 

 confluence of the Vaal and Orange Rivers irrigate about 3,200 

 acres, while the existing pumping plants irrigate about 

 7,000 acres. There are at present 43 i)umping olants between 

 Vereeniging and the confluence, and it is estimated that there are 

 about 60 pumping plants on the whole length oi the Vaal. 



Estimated Area of Irrigable Land. 



About 500,000 acres are available for irrigation within 

 the Vaal River catchment area, and the greater portion of the 

 area is downstream of Vereeniging. The quantity of water 

 required for irrigating 500,000 acres, taking an all-round figure 

 for the various classes of crops and fruit trees, will b.e about 

 =0,000 million cubic feet, and owing to occasional years of low 

 flow, it will be absolutely necessarv to impound sufficient water 

 in storage reservoirs to cover a period of at least 18 months. It 

 should, however, be mentioned that although the catchment area 

 above Vereeniging is only 16.319 square miles, as compared with 

 4.6,087 , square miles at Kimberley, the actual discharge at 

 Kimberley over the period 1900-1904 was only 1.9 times as much 

 as at Vereeniging. 



Generation of Power from Coal-fields Adjoining the River. 



There are several places on the Vaal River coal-fields where 



cheap electrical power can be generated for driving pumping 



