THE IKRIGATION AGE. 



83 



the weight of each substance in the surface soil eight 

 inches deep: 



Elementary bodies and their com- Per- 



binations. centage 



Silica and fine sand 87.143 



Alumina 5.666 



Oxides of Iron 2,220 



Oxides of Magnesia 0.360 



Lime 0.564 



Magnesia 0.312 



Potash combined with Silica 0.120 



Soda combined with Silica 0.025 



Phosphoric Acid combined with Lime 



and Oxide of Iron 0.060 



Sulphuric Acid in Gypsum 0.027 



Chlorine in common Salt 0.036 



Carbonic Acid united to the Lime... 0.080 



Humic Acid 1.304 



Insoluble Humus 1.072 



Organic substances containing Nitro- 

 gen 1.011 



Total Inorganic and Organic sub- 

 stances 100. 



Weight in 



pounds 



3,203,781+ 



208,308+ 



81,617+ 



13,235+ 



20,735+ 



11,470+ 



4,411+ 



919+ 



2,205+ 



992+ 



1,323+ 



2,941+ 

 47,941+ 

 39,411+ 



37,169+ 



3,676,464 



It should be remembered that these immense quan- 

 tities are contained in only eight inches of top soil, and 

 that twelve inches, or one foot of soil, which is about the 

 depth before reaching the subsoil, would contain a total 

 of inorganic and organic matter equal to 5,514,696 pounds, 

 or 2,757 and one-third tons. 



The calculation is made by multiplying 43,560, the 

 number of square feet in an acre, by 126.6 pounds, the 

 estimated average weight of one cubic foot of wet soil, 

 which gives the weight of one acre twelve inches deep. 

 Then dividing by twelve, we get the weight of an acre 

 one inch deep. To ascertain the weight of eight inches, 

 we have only to multiply by eight inches, and again mul- 

 tiply by the number of parts of any organic or inorganic 

 matter to ascertain the exact weight of that particular 

 matter in the acre, thus: 



43,560X126.6=5,514,696 pounds per acre one foot deep. 



5,514,696-4-12=459,558 pounds per acre one inch deep. 



459,558X0.120=551.46960 pounds of Potash in one inch 

 acre. 



551.46960X8=4,411 pounds of Potash in acre eight 

 inches deep. 



Five right hand figures must be cut off, three for 

 the decimal places and two more because the calculation 

 is based on a percentage of one hundred parts. 



The average weight of a cubic foot of dry soil, ac- 

 cording to the foregoing estimate, based upon the tests 

 taken in the cases of five hundred soils collected from 

 various places on the globe, is 94.58 pounds, which will 

 make the dry soil acre eight inches deep weigh 2,715,792 

 pounds, a difference in weight between wet and dry soils 

 of 960,672 pounds per acre eight inches deep, which, of 

 course, represents the weight of water. 



This information will prove of value in considering 

 the question of applying water to the soil. As a rule, 

 the proportions of inorganic and organic matter remain 

 about the same, except that the application of water by 

 irrigation adds to the quantity in soluble matter carried 

 to the soil, which is greater in the case of irrigation than 

 when rain is depended upon, humus and salts in solution 

 being carried in the ditch water. 



By referring back to the test table of a specimen 

 soil, it will be noticed that -the first twelve substances 

 are "inorganic," and the three last "organic." It will also 



be noticed that the proportion of inorganic matter is vastly 

 greater than that of the organic. It is necessary that this 

 should be so, for the organic matter is the "active" prin- 

 ciple, the dynamic force, and the inorganic matter the 

 "passive" principle. If the proportions were reversed, the 

 inorganic matter would react upon and destroy itself, 

 and as it could not be replaced very well, there would 

 soon be an end to the growth of plants. Hence, nature 

 provides a store-house of raw material, so to speak, to be 

 utilized in the manufacture of plant food, and it is practi- 

 cally inexhaustible, the subsoil, for an unlimited depth, 

 containing all the ingredients necessary to restore the 

 top soil should it become jaded and unresponsive to the 

 demands of cultivation and fertility, if the farmer will 

 take the trouble to dig down after them and bring them 

 to the surface. 



Moreover, the inorganic elements in the soil are per- 



SOPHUS RICHARD, 

 General Manager and Treasurer, French Land & Irrigation Company. 



manent. They are insoluble except when acted upon by 

 the acids formed through the chemical action of the or- 

 ganic matter, and the vital force exercised by the growing 

 plant. 



In the table of specimen soil, given on another page, 

 the percentage of inorganic matter passes 95 per centum, 

 while the organic matter is about three and one-half per 

 cent. Yet that particular soil is a fertile one, in which 

 it is possible to produce a good crop of any kind of 

 plant. It is only an analysis, it is true, and a chemical 

 analysis is not Always to be depended upon, because 

 there are so many unknown and mysterious applications 

 of the laws of nature, but there are many things to be 

 said in favor of ascertaining what ingredients the soil does 

 contain, approximately, if not with rigorous exactitude. 

 It gives the practical farmer valuable information in the 

 form of suggestions for the improvement of the soil. It 

 (Continued on page 100.) 



