— 31 — 



resting is th's: that below the humid layer on old ploughed soil lies as 

 we saw before, a dry layer, which however contains about 10" ,, of wa- 

 ter (useless). But on waste land th's dry layer (show on the diagrams 

 by vertical lines) has only 6 to 8" ,, that s to say it 's much poorer 

 in water than the old plougled fields. Comparing the two cases— the 

 course of humidity on oldploughed and waste land — we see that in the 

 former case the humid layer is thicker and the underlying dry layer 

 holds more water. Consquently, the yearly balance of water in root-inha- 

 bitable layers of waste-land is undoubtedly less than in old ploughed soil, 

 and that is the defective side of leaving fields to lie fallow, as a remedy 

 against drought. For th's old-fashined point of view is diametrically 

 opposed to the truth. The tillage of virgin steppe does not encourage 

 drought, but minimizes it, changing waste land into old ploughed land 

 with its larger yearly balance of water. Therefore // must be admitted 

 that allowing afield to lie waste /or seueral years is injurious to irrigation. 



The /jermanent humid soil layer or lower humid layer. 



On old ploughed fields (fig. 10 and others) at a depth of 160 to 

 180 cm. (4' ■_' to 5' -j feet) the permanent humid layer commences, which 

 holds a certa'n quantity of useful water — about 1,2 or 3"',, — all the year 

 round. It extends without interruption, to the ground water, on our step- 

 pes to 140 or 175 feet. On waste land the permanent humid layer lies 

 far deeper than on old ploughed land about 14 to 30 feet. The perma 

 nent humid layer on old ploughed land is shown at the botton of the 

 diagrams by grey shading, but on waste land it is not noticed even at 

 a depth of 240 cm. — This simple fact — the layer lying at several fathoms 

 on waste land and at a few feet on old ploughed land shows that the 

 depth where the permanent humid layer lies is not constant; and the 

 more the farmer endeavous to accumulate water in the soil, not by let- 

 fng the land lie idle, but by its culture, the nearer, the permanent hu- 

 mid layer will get to the surface. 



7y:e intermediate dry layer ■■). 



Between the upper humid layer of soil, periodically moistened by 

 atmospheric residue on the surface, and the lower permanent humid 



*) H. N. Visotzkii calls this layer „The dead horizon of dryness", but we 

 cannot agree to this title, for, as we shall see later, one year under black fal- 

 low would make the soil „alive" and habitable for plant roots. The role of the 

 intermediate dry layer is only mentioned by H. N. Visotskii as iar as it con- 

 cerns forest growths. 



