66 ECONOMY OF FARMING. 



dry climate, while it is worth little in a cold, moist climate. A loose, sand-soi], is worth 

 little ill a dry. hot climate, while it is more valuable in a moist one," &c. 



As to the power of the soil to retain moisture, he says, p. 291 : "Next to the power 

 of a soil for takinof up water into its pores, the greatest importance for vegetation is, 

 how long it will hold the moisture so taken up. Many soils soon lose the water by 

 evaporaSon : others, on the contrary, very slowly. Sand, lime-stone, gravel, and 

 slaty kinds of soils, dry up the quickest, and on that account form the so-called hot 

 soils, while clay, which holds water long, is named a cold soil." 



Professor Schubler found, by many experiments on the power of soils to retain 

 water, the following results : 



KINDS OF CARTH EASE OF DRYING UP. 



Of 100.0 parts of water absorbed, ]Of 100.0 parts of water absorbed, 

 was evaporated at 15" Reaumur 90.0 parts evaporated at 15' Reau- 



= 67" Far. in 4 hours. 



Q,uartz sand . . . . 



Lime " . . . . 



Gypsum in earthy form 



Stratified clay 



Loamy " . . . . 



Pure gray " . 



Carbonate of Ume in a fine state 



" '• magnesia " " 

 Humic acid 

 Loamy soil .... 



mur = 67° Far. in 



" On the drying up of the deep layers of the soil in a longer or shorter time, the dif- 

 ferent looseness or consistency of the upper soil, has also an important influence ; the 

 Jine clay, for example, at 2 inches thickness strata, has a moist surface long after the 

 surface of the peaty soil at the same depth is dried up. 



The power of the soil to retain water in all depends on : 1, The quality of the sub- 

 soil; 2, The quality of the upper soil ; 3. The degree of warmth by the sun ; 4, The 

 atmospheric pressure, and the degree of the change of the atmosphere. The atmos- 

 pheric pressure has great influence on the evaporation ; and on this account a soil 

 dries up so much the more rapidly, by how much higher it lies, and the more it is 

 struck by the wind, especially the east wind. 



" If a soil contains many salts which attract moisture from the air, this has great 

 influence also on the evaporation, as these by night absorb again the water 

 evaporated." 



Respecting the property of the earth to attract moisture from the atmosphere, he 

 also observes, p. 294 : 



" Besides quartz-sand, all the earths which constitute the soil have the property, 

 BO far as they are dried to a certain degree, more or less to attract moisture from 

 the air, which is naturally of high importance for the growth of plants. In the 

 strongest degree, generally, this affinity for moisture in the atmosphere shows itself 

 in the clay soil, especially if it contains much humus ; since these bodies, of all the 

 constituent parts of the soil, attract the most moisture from the air ; the kinds of humus 

 indeed are somewhat differently proportioned ; the heath-humus, for example, be- 

 cause it contains so much carbonized humus (or humic carbon) and resinous wax, 

 attracts not so much moisture from the air as the mellow humus, which in a great 

 measure consists of humates or salts of humic acid. 



"All earths attract more moisture by night than by day ; they also give back, through 

 evaporation in the sun-light the moisture absorbed by night. 



" From the capacity of the soil to attract more or less moisture from the air, we 

 might likewise form a conclusion as to the degree of its fertility, yet we can thereby 

 come to no certain result, as a leaner clay soil absorbs more moisture than a richer 

 loam soil. 



" In order to ascertain hov; much moisture one kind of soil will absorb from the air, 

 we laid a certain quantity of finely pulverized and fully dried earth on a plate, which 

 was put under a glass bell made water-tight and left it to lie there 12, 24, to 43 

 hours, in a moderate temperature (12° to 15" Reaumur, =59° to about 67° Far.) and 

 then weighed it The addition of weight exhibits the quantity absorbed in watery 

 vapor." 



