172 



THE IRRIGATION AGE. 



moisture below, then the rain may be a distinct benefit. 

 In any case, shallow-rooted crops are often temporarily 

 benefited, but unless a cultivation can follow, the soil 

 at and near the surface usually soon becomes baked 

 and the crop is often worse off than before the rain. 

 The crops benefited most by the local rains are the win- 

 ter grains. Being shallow rooted, and growing during 

 the cool time of the year when evaporation is less rapid 

 than at other times, they often receive considerable 

 benefit from the rains of December, January and Feb- 

 ruary. Some of the July and August showers benefit 

 such crops as strawberries, tomatoes, and other shallow- 

 rooted ones. But the effect of a rain upon a crop is 

 seldom lasting, and only a small portion of that which 

 falls can be considered as consumed by a growing crop. 

 Of greater importance than the local rains are the 

 storms in the mountains constituting the watershed of 

 the Salt River, the source from which the irrigating 

 water is drawn. As the mountain rains usually occur 

 at the same time as the valley rains, the latter are 

 usually welcomed because of the simultaneous occur- 

 rence of the former, rather than because of their own 

 direct value. 



RAINFALL FOR 1898 AT STATION FARM. 



Inches. 



January 10 60 



January 13 22 



January 27 70 



July 4 20 



August 22 30 



August 26 70 



November 25 07 



Inches. 



November 26 53 



November 27 01 



December 9 63 



December 10 1.31 



December 11 02 



December 16 02 



Total . . 5.31 



The rainfall of the year, it will be observed, all fell 

 during but five months of it, none falling from January 

 to July, nor during September or October. The rain 

 was thus confined almost entirely to the two rainy sea- 

 sons mentioned above. As usual also, the greatest 

 amount fell during December. 



RAINFALL FOR 1899 AT STATION FARM. 



Inches. 



January 11 23 



January 12 $7 



February 2 09 



February 3 02 



June 24 29 



June 25 76 



July 

 July 



9 



10 



.16 

 .01 



July 12 12 



July 15 03 



July 18 33 



July 19 33 



Inches. 



July 24 12 



July 31 14 



August 3 81 



August 6 18 



August 15 54, 



September 8 '. .89 



October 11 29 



October 12 01 



October 14 04 



November 14 42 



November 22 06 



December 18 12 



Total . . 6.96 



The rainfall of this year was distributed more 

 evenly, fell in a large number of showers, and exceeded 

 in total amount that of the year preceding. An un- 

 usually small amount fell during February and Decem- 

 ber, and an unusually large amount during June. It 

 will be noted that none fell during March, April or 

 May. 



RAINFALL FOR 1900 AT STATION FARM. " 



Inches. 



January 4 10 



March 13 10 



March 14 13 



March 25 03 



April 5 56 



April 28 39 



May 5 10 



July 20 1.30 



Inches. 



August 3 03 



September 1 08 



September 22 01 



October 12 20 



November 17 44 



November 18 64 



November 19 67 



Total . . 4.65 



The rainfall this year was abnormally small during 

 the winter rainy season, but one-tenth of an inch falling 

 during that period. This was partially compensated 

 for by the unusual rainfall for April. The rain of 

 July 20 and of November 17-19 was sufficient -in 

 amount to directly benefit growing crops. It will be 

 noted that none fell during February, June or Decem- 

 ber. The total precipitation was below that of any 

 previous year since a record has been kept at the farm. 



RAINFALL FOR 1901 AT STATION FARM. 



Inches. 



January 25 38 



January 27 04 



February 1 36 



February 3 02 



February 6 68 



February 7 05 



February 10 11 



February 11 01 



February 24 03 



March 8 09 



March 31 14 



May 14 15 



May 29 06 



July 2 01 



July 23 08 



Inches. 



July 24 07 



July 27 05 



July 29 59 



.02 



.06 

 .97 

 .01 

 .02 



Juiy 30 

 August 1 

 August 3 

 August 4 

 August 5 



August 11 22 



August 12 06 



August 13 05 



August 17 14 



August 29 21 



October 29 55 



November 12 .13 



Total . . 4.36 



The year was characterized by the unusual number 

 of showers that fell, especially during February, July 

 and August. With the exception of the absence of rain 

 during December, as during the previous year, the 

 precipitation fell during the usual rainy seasons. The 

 total of the thirty showers was, however, smaller in 

 amount than that of any. previous year of which there 

 is a record at the farm. On very few days did enough 

 fall to be of much direct benefit to crops. However, 

 during the winter season, three rains, varying in 

 amount from one-third to two-thirds of an inch, oc- 

 curred that would benefit growing grain. But the total 

 amount, 1.42 inches, is small compared with the amount 

 required to produce the crop. One of the July showers 

 that of the 29th and one of the August ones that 

 of the 3rd would also benefit considerably some of 

 the summer crops, such as strawberries, tomatoes and 

 cotton. Possibly an average of a tenth of a foot might 

 be counted as the amount of rain utilized by each crop, 

 in addition to the irrigating water applied during the 

 year. It will be noted that during March, May and 

 the most of July, the rainfall on no date was sufficient 

 to wet dry soil to a greater depth than one-half inch, 

 that none fell during April or June, and none during 

 the two months from August 29 to October 29. 



TEMPERATURE AND RELATIVE HUMIDITY. 



The coolest months at the station farm are De- 

 cember and January, during which frosts (occasionally 

 heavy ones) are frequent. During February the weather 

 commonly becomes gradually warmer. It may be con- 

 'sidered that this month marks the beginning of spring. 

 The principal part of the growth of winter-sown crops 

 is made during the three months that follow. During 

 these months the weather becomes increasingly warm, 

 the maximum temperatures, by the latter part of June, 

 ranging from 100 to 110 F.' in the shade. The rela- 

 tive humidity of the atmosphere decreases as the season 

 advances and the temperatures rise, evaporation conse- 

 quently becoming very rapid. During July and August 

 the temperature is higher than during June; but the 

 humidity is temporarily increased from time to time 

 by rains and the weather is consequently often less try- 



