SOILS — FERTILIZERS, 815 



Wcallior P.iiroan stations noar tin- iMHiiulaiy <>f tlic valley. Stream ineasure- 

 iiieiits were made aii|in».\imately every '2 wi'eks friuii .January (i to Decemlier 

 23, an'l samples of water were taken for analysis at the same time. Determina- 

 tions were ma<le of eblorin, nitrogen, total solids, loss on ifjnition, and reaction. 

 The drninaKe water per acre for the period covered was 5!),470.92 cii. ft., the 

 rainfall 202.520 cu. ft., the evaporation 143,040.08 en. ft. 



Acct)r(linf; to the analyses reported, the drainaije water removed from 1 

 acre of the soil of this area in one year 704.0.38 lbs. of total solids. 340.200 lbs. 

 of silica, 1.34.134 lbs. of organic and voL-itile matter (loss on ignition), 80.4G7 

 lbs. of alumina. 80.701 lbs. of lime, 17.728 lbs. of sulphur trioxid. 13.08 ll»s. of 

 chlorin, 10.00.") lbs. of mafinesia. 4.817 lbs. of potassium oxid. 4.012 lbs. of 

 nitrogen, 3.01 lbs. of sodium oxid, 1.080 lbs. of ferric oxid. 0.n;j3 lb. of man- 

 ganous manganic oxid, and 0.057 lb. of phosphorus pentoxid. 



The average composition of the surface G in. of soil of the region is given as 

 follows: Water 5.53, silica 86.67. alumina 3.16, lime 0.20, sulphur trioxid 0.11, 

 magnesia 0.16. potassium oxid 0.11. nitrogen 0.061, sodium oxid 0.16. ferric oxid 

 2.22, manganous manganic oxid 0.12, and phosphorus pentoxid 0.112 per cent. 



"Taking the weight of 1 cu. ft. of soil at 70 lbs., this would mean that 

 the drainage water removes 0.00313 in. of soil annually, or it would require 

 about 300 years to remove 1 in. of soil by drainage water. . . . 



"The annual loss per aci'e due to drainage water amounts to: Nitrogen, GO 

 cts. ; iK)tassium. 25 cts. ; and phosphorus, about 4 cts. This would make an 

 annual loss i)er acre of 89 cts. 



" During the growing season the evaporation amounts to more than 00 per 

 cent of the rainfall, while for the whole year the evaporation amounts to 70 

 per cent of the rainfall." 



Distribution of water in the soil in furrow irrigation, R. H. Loughridge 

 ( r. N. Ihiit. Af/r., Office K.riit.. Stus. liul. .iO.i. />/>. Hi. /if/s. /.O).— This bulletin 

 records the results of cooperative experiments carried on by this Office and the 

 State of California to determine the extent in area and dei)th to which water 

 l>ercolates beneath furrows, as well as the proportion retained by the soil for 

 the use of orchard trees. The experiments formed a part of a general study 

 of the losses of water in irrigation and their prevention, investigations on 

 tvajHiration having already been re|torted ( E. S. K., 18. p. 1(»S7). 



The experiments were made mainly (»n sandy loam soils in citrus orchards 

 near Riverside, Cal. The character of the soil and its moisture content to a 

 depth of several feet were determined before the experiments were begun. 



To as(^'ertain the rate of movement of the irrigation water in the soil and 

 the amount of moisture retained, trenches were dug across the irrigation fur- 

 rows to a depth of 5 or 6 ft. and of convenient width. liy means of these 

 trenches it was possible to trace the rate and ex'v'.it of percolation of the irriga- 

 tion water and also to take samples at any desired depth for determination of 

 moisture. 



In view of the somewhat niiusnal cliaraclcr of tli«> investJLrations. an imiiortant 

 feature of the work was the development of methods suitable to the pur|>ose. 

 The experience gained indicates certain im|)ortant improv«'ments in methtMls, 

 which are described in detail. The principal results of the percolation studies 

 are summarized as follows: 



"The preliminary examination of the land of the orchard before irrigalion 

 showfHl that the upper 2 ft. held only about 3.5 per cent of frw water as the 

 general average, while below this to the depth of 13 ft. the average was (5.16 

 F)er cent. Tlie roots of the trees were mostly conlined to the ui>iier 4 ft., and 

 In this depth there was au average of 4.68 per cent, an amount suUicient to 



