THE IRRIGATION AGE. 



185 



Yield in tons per acre, 



The following diagram was then shown, prov- 

 ing that "from two and one-half to three acre-feet 

 of irrigation water per acre per year is sufficient 

 for the growth of maximum economic yields of 

 alfalfa on the medium loam soils of Sacramento 

 Valley." 



OE 



>TH OF //?fi;c/moM IN INCHES 



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That statement is correct if the intention of the 

 experiments was to determine the greatest amount 

 of produce that can be raised from an acre of land ; 

 but the title of the bulletin presupposes that the in- 

 tention of the experiments was the determination of 

 the greatest amount of produce that can be raised by 

 the use of a certain quantity of water applied in 

 irrigation. 



Suppose a man is the owner of the right of use 

 of thirty acre-feet of water, and he wants to know 

 how he can use that quantity to the best advantage 

 in raising alfalfa. He reads the conclusions of the 

 compiler of the bulletin, and naturally decides the 

 best he can do is to use that water upon 10 acres 

 of land, for the summary shows he will get 92.70 

 tons of hay, and have a profit of $369.30, if he sells 

 it at $7.00 a ton. 



But suppose he is not satisfied to follow the 

 conclusions printed for his guidance, and studies out 

 the summary for himself. The first thing he will 

 find is that if he puts the water upon 30 acres of land, 

 he will get 168.90 tons of hay, and have a profit of 

 $729.20. That is, he will almost double his crop re- 

 turns and his profit. 



Now, if he gets a little more inquisitive, he 

 will look at the returns, cost and profit if he does not 

 irrigate his land at all. He will see that if he should 



give or sell his water right to some neighbor, the 

 amount he would expend in raising the 169.90 tons 

 of hay, will raise 204.90 tons, and his profit will be 

 $973.10. 



Is not the 204.90 tons of hay, and profit of 

 $973.10 a great deal better than 92.70 tons of hay, 

 and profit of $369.30 he would get if he follows the 

 advice given in the bulletin? 



Now, suppose he goes into the financial end of 

 the report, with the desire of finding out just how 

 far he can have a thousand dollars go in raising 

 alfalfa. A few minutes calculation will show the 

 following : 



Irrigating with 60 acre-inches per acre. Profit, 

 $1,002.00. 



Irrigating with 48 acre-inches per acre. Profit, 

 $1,170.00. 



Irrigating with 36 acre-inches per acre. Profit, 

 $1,321.00. 



Irrigating with 30 acre-inches per acre. Profit, 

 $1,376.30. 



Irrigating with 24 acre-inches per acre. Profit, 

 $1,387.70. 



Irrigating with 18 acre-inches per acre. Profit, 

 $1,460.00. 



Irrigating with 12 acre-inches per acre. Profit, 

 $1,564.00. 



Without any irrigation at all. Profit, $2,113.00. 



There is a steady increase in crop returns and 

 profit with decrease in quantity of water used per 

 unit of land irrigated. The result is exactly the same 

 as when a man places upon one acre of land the 

 potash that should be spread over ten acres. The 

 only difference is that in case of the water, it will 

 leave the land in short time, and the land not be in- 

 jured unless the practice is kept up ; while it will 

 take some time to get rid of the potash. 



Examining the summary from standpoint of the 

 plant, it will be seen that, after deducting the 

 amount of hay raised per acre without irrigation, 

 the balance shows that there is a very small increase 

 in quantity per acre-foot of water used in irrigation 

 up to 30 inches, and then a sharp decrease ; but as 

 a whole the returns per acre-foot of water are far less 

 than those without irrigation. For instance ; with- 

 out irrigation, the returns are 2.74 tons per acre-foot 

 of water ; the first 12 inches irrigation only returns 

 1.75 tons; at \ l / 2 acre-feet irrigation it is at rate of 

 1.95 tons per acre foot; at 2 and 2 l / 2 acre-feet, the 

 returns were 2.02 and 2.04 tons per acre-foot ; at 3 

 acre-feet it was only 1.80 tons per acre-foot, and at 

 5 acre-feet, it was 0.93 tons per acre-foot. 



The conclusions to be derived from these figures 

 are plain. Without irrigation, the standard of water 

 supply needed by the alfalfa for its best growth and 

 foods furnished, is reached closer than with irriga- 

 tion. The plant responds to the increased water 

 supply with a larger structural growth up to 30 

 inches. Then the water supply gets the best of the 

 plant, and it rapidly degenerates. In the same stages 

 the food producing powers become less with each 

 increase of water supply. This is not shown in 

 the report, but practical results in feeding stock 

 with alfalfa hay raised under small and large quanti- 

 ties of water supplied are frequent. One ton of the 

 hay raised without irrigation is worth in feeding 

 value several tons raised with irrigation of five feet. 



The greatest value of this Bulletin No. 280 is 



