3U8 Transactions of TnE 



for any over-estimate on this point, let us neglect their flow for the re- 

 mainder of the year. 



AMOUNT OF WATER NECESSARY FOR IRRIGATION. 



How much land ought a cubic foot of water, supplied every second 

 for iwo hundred days, to irrigate? Wo will make a further supposition 

 that the water is used for fourteen hours out of the twenty-four. Irri- 

 gation at night is practiced in other countries, and we may be assured 

 that in seasons of scarcity it will be practiced here, if it shall prove to 

 be necessary to save the crops. In fourteen hours there are fifty thou- 

 sand and four hundred seconds, and hence, one day's supply at one 

 cubic foot per second, will give us the same number of feet. Deducting 

 fifteen per cent for loss by absorption and evaporation, we shall have 

 remaining forty-two thousand three hundred and forty cubic feet, which 

 number, although a little less, we may take to be the same as the num- 

 ber of square feet in an acre. Hence, one day's supply will put twelve 

 inches of water over an acre, or two inches of water over six acres, and 

 in two hundred days a supply of a cubic foot per second will cover two 

 hundred acres with twelve inches of water. Wheat planted in October 

 or November on Summer-fallowed land, well watered, when the rivers 

 are high, will probably make a good crop without watering, except 

 what it gets from the Winter rains, even when they prove scanty. 

 "Wheat planted in January or February will probably need one or two 

 irrigations of three inches each, to make a crop. Wheat or barley 

 planted later, and with irrigating facilities — there seems to be no reason 

 why, in these hot valleys, the sowing time may not be extended to 

 April — will probably ripen with twelve inches of water judiciously 

 applied. 



RAINFALL REQUIRED FOR CROPS. 



We know that the good crops of wheat are raised without irrigation 

 where there is a rainfall of twelve inches, or even less, which comes at 

 the required times. On the tule or reclaimed lands, barley sowed after 

 wheat harvest has been gathered, comes to maturity. The water 

 required for cotton wdl probably not exceed that necessary for wheat. 

 Bice cultivation is so unhealthful that its introduction into California 

 will hardly be looked upon with favor. Alfalfa, if cut live times for 

 hay, will require twelve inches of water or more, depending on the 

 nature of the soil; this in addition to the usual rainfall. There is 

 another point to he considered. The whole of the land commanded by 

 the canal will not be irrigated; some of it will be waste or unsuitable 

 for cultivation; some will be fallow, and if Ave add the areas taken up 

 by the roads, fences, buildings, farm-yards, etc., we ought, according to 

 experience elsewhere, to deduct one fourth at least from the irrigable 

 land. This deduction of one fourth, we assume, will make up for any 

 kind of cultivation, such as gardens, orchards, etc., requiring larger 

 supplies of water. Our opinion is, therefore, that a reasonable allow- 

 ance for the land commanded by the canals is one cubic foot a second 

 for each two hundred acres. In seasons when there is a great surplus 

 of water, there can be no objection to a more liberal use of it; but it 

 seems to us indispensable that the State should lay down 



