Farm Irrigation. 465 



^243,702. Now, if this valuable local trade is ever to be retained 

 in our own hands, the tobacco growers must produce larger 

 quantities of improved leaves of uniform quality. It is quality, and 

 not weight, that is going to pay in the future. 



Many people in South Africa appear to think that irrigation 

 consists entirely of the works necessary for storing, or diverting, 

 water and delivering it to the farmers ; but while I fully realise 

 the importance of the work that has to be done by Irrigation 

 Engineers, I am also aware that real development does not rest 

 solely with them. The economical and scientfic use of the water 

 by farmers is a very important factor, and that is the point to 

 which I would like to give special emphasis. The methods employed 

 to-day are little better than those employed by the early settlers. 

 It has been the same in the United States, but the go-ahead people 

 there are alive to the importance of the proper use of water, and 

 the question is being investigated by experts. It has been found 

 that the area of land that could be irrigated by the rational use of 

 water might be doubled or trebled, and it is easy to see what an 

 advantage that would be to this country. It would mean that the 

 cost per acre for water would be reduced to one-half or one-third. 

 This saving of water is obtained by only using the amount required 

 to get the best results. Different crops require different treatment, 

 and improper irrigation is injurious to any crop ; for instance, oats 

 require more water than any other grain, cotton needs very little, 

 too much water spoils tobacco, turnips, parsnips and carrots should 

 never be flooded, and flooding lucerne during the first six months 

 of its life is pretty certain to check the growth. 



Much valuable information was given by Dr. J. Widstoe in 

 a paper read before the Twelfth National Irrigation Congress in 

 the United States of America. He said that on a typical western 

 soil, 5 inches of water produced 33 bushels of wheat per acre; 

 ID inches of water produced 40 bushels. Adding more than 20 

 inches of water to the field did not appreciably increase the yield of 

 grain. In the case of the wheat plant, then, the increase of the 

 amount of water up to about 15 inches increases the yield of grain, 

 but a further application tends to diminish the yield. When it is 

 considered that the depth of water applied to the wheat, over a 

 very large area of irrigated country, amounts to 30 or more inches 

 annually, it will be understood what a loss in wheat alone occurs 

 year after year through the misuse of water. 



With oats the variation is somewhat similar. Five inches of 

 water in one set of experiments yielded about 58 bushels of oats per 

 acre ; 10 inches yielded about the same amount, though the increased 

 quantity of water increased the weight of the straw. With 15 

 inches 70 bushels were obtained ; with 20 inches 86 bushels ; and 

 with 30 inches 82 bushels. Covering the land with more than 30 

 inches of water diminished the yield of oats decidedly. About 20 

 inches is therefore the best amount of water for oats ; yet throughout 

 the irrigated West 30 inches or more are generally used in the 



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