TEE AOBICULTUBAL JOURNAL. 



491 



Umgbni Project. 



13. Mr. G. C. Williams brought to my 

 notice in 1899 a promising scheme for 

 bringing the water of the Umgeni down 

 to Pietermaritzburg from the railway 

 bridge above Howick, thus providing 

 water supply and power for the City, as 

 well as irrigation for some very good soil 

 below Otto's Bluff. He has since more 

 publicly mooted the scheme. There are 

 certainly some very excellent lands that 

 would be brought under irrigation — some 

 thousands of acres — and the Umgeni 

 would at its worst give ample water for 

 water supply, and the surplus of power 

 water could, perhaps, be used for irriga- 

 tion. The drawbacks to this scheme are 

 the long distance that the water has to be 

 brought before it begins to l^e remunera- 

 tive and the somewhat uncertain supply 

 of the Umgeni under the wors' cii-cum- 

 stances of drought. It has certainly 

 sometimes been as low as 50 cubic feet 

 per second in 1900, but I do not think it 

 has been sensibly lower. The ordinary 

 minimum may probably be safely taken 

 at 100 cubic feet per second. The canal 

 will have to pass through moi-e than 25 

 miles of country, much of it difficult, 

 before it begins to irrigate ; the loss in 

 this length must be very considerable, not 

 to speak of the cost. On the other hand, 

 there seems reason to believe that such a 

 season as 1900 is not likely to occur \ery 

 often, and even in such a season there 

 would be amply sufficient for water 

 supply. As to power, I have no data. If, 

 then, it is approved as a scheme for water 

 supply and power, the survey should be 

 carried out. As a purely irrigation pro- 

 ject, I do not think it would pay, though 

 I should be sorry to see it finally shelved 

 without any further investigation. 



14. I know, as yet, of no other projects 

 for public canals that could be suggested 

 for the consideration of Government. 



Shallow and Porous Soils. 



15. Much of the soil in Natal is very 

 shallow. Over a large area is found 8 or 

 10 inches of loam over shale, and the 

 upper 3 or 4 inches of this shale is very 

 much broken up. Sometimes under the 

 loam there is a band of some three inches 

 of fine gravelly stuff. In either case, it 

 is evident that the subsoil is exceedingly 

 porous, and that if water is run freely on 



to it for irrigation, not only is an enor- 

 mous depth of water used on each acre, 

 but the soluble plant-food in the soil 

 must be partially washed away. The 

 difficulty can be got over to some extent 

 by the use of pipes, troughs, or hose, 

 which involves considerable expense. If 

 it is found that the underflow is not too 

 deep to reach the roots of the crop, irriga- 

 tion may possibly be effected by running 

 the water down parallel furrows at a 

 suitable distance apart, without attempt- 

 ing to spread it over the surface of the 

 field. The porosity of the soil is greatly 

 diminished after the first watering, and 

 each watering must be conducted accord- 

 ing to its own special conditions. 



Furrows from Spruits. 



16. Most of the permanent " spruits," 

 i.e , those that run throughout the dry 

 season, can be, and frequently are, utilised 

 bj taking out a small furrow to the 

 nearest suitable land. Frequently, how- 

 ever, the land where the water is desired 

 is a considerable distance from the spruit, 

 and it may be doubtful whether it can 

 travel so far without losing most of its 

 volume. Li a case in Mid-Illovo, a small 

 stream, sufficient for about 20 acres, could 

 have been used on the spot, with no ex- 

 pense whatever, on a suitable tract of 

 moderately sloping ground, but the 

 owner did not wish to cultivate, and if 

 utilised at all it will have to be taken 

 about a mile by another farmer, and 

 carried across a valley by a siphon pipe. 

 It is doubtful whether this will pay. In 

 most of the cases that have come before 

 me of taking out small furrows from 

 spruits and small rivers, there have been 

 no great difficulties in the way. In the 

 case of the Mooi River, the available 

 supply is already, by all accounts, pretty 

 well utilised by several small channels. 



Diversion Reservoirs. 



17. The imperfectly permanent spruits, 

 i.e., those that are liable to fail more or 

 less in the course of the dry season, can 

 very generally be made available for irri- 

 gation. There are probably few farms on 

 which one or two acres of irrigation can- 

 not be seemed in this way. A furrow 

 should be taken out from a suitable point 

 on the spruit, and led to a suitable slope 

 ( 1 in 1,000 to 1 in 500, or possibly steeper 



