195 



A top dressing of waste lime from sugar factories is often made use of 

 in the cultivation of beets. The mechanical efifect makes itself felt not in- 

 frequently by the fact that, as a result of increased capacity for being heated 

 and the scanty supply of water, these soils later cause heart rot and dry rot. 



Hilgard's statements^ on the "alkali soils" of California are of great 

 interest. The alkali places often found between excellent cultural lands con- 

 tain so much salt that they become noticeable by efflorescence on the surface. 

 Those which contain alkaline carbonates (and partially also borates) are dis- 

 tinguished by the difficulty or almost impossibility of producing a really 

 friable soil. After each rain, a coffee brown, clay water, colored by dis- 

 solved humus, stands at times for weeks on those places, recognizable be- 

 cause of their lower position. The same working of the soil which gives 

 good soil the consistency of loose ashes makes the alkaline land a mass of 

 rounded clods varying in size from a pea to that of a billard ball. 



After evaporation, heating and saturation with carbon dioxid, the 

 blackish brown solution, leached from alkaline soil, gives 0.251 per cent, in- 

 combustible residue. Of this 0.158 per cent, was redissolved in water and 

 this soluble part consisted of 52.74 per cent, sodium carbonate, 33.08 per 

 cent, sodium chlorid, 13.26 per cent, sodium sulfate, 1.83 per cent, sodium 

 triphosphate. 



The 0.093 per cent, insoluble residue from the heated water extract con- 

 tained 14.02 per cent, calcium carbonate, 5.37 per cent, calcium triphosphate, 

 5.77 per cent, magnesium triphosphate, 24.37 P^i* cent, silica soluble in 

 NaoCO;;, 50.47 per cent, of ferric oxid, aluminium oxid and some clay. 



In this case, as well as in many other alkaline soils in California, the ad- 

 dition of a sufficient amount of gypsum (land plaster) produces a striking 

 effect. The caustic action of the alkaline carbonates on seeds and plants 

 stopped at once so that where previously only "alkali grass" (Brizopyrum) 

 and Chenopodiaceae grew, maize and wheat were produced without difficulty. 

 The g}^psum naturally requires a longer time for the mechanical change of 

 the soil surface and its greater loosening. 



Inundations. 



In opposition to the frequently widespread anxiety when volumes of 

 water break over cultivated land, it might be emphasized that, naturally, 

 aside from the washing away of nutritive substances and the mechanical 

 injury due to the pressure of the waves, vegetation is not extremely sensi- 

 tive to a water cover over the soil for some time. Woody plants especially, 

 as floods show, possess a great power of resistance, which continues as long 

 as the water keeps moving. 



Stagnant water, remaining for a long time on the surface of the soil, 

 works the greater harm ; for a shorter time, inundations in the form of 



1 Hilg-ard, Ueber die Flockung- kleiner Teilchen und die physikalischen und 

 technischen Bezichunpen dieser Erscheinung. American Journal of Sciences and 

 Arts. XVII, March 1879. Forsch. auf d. Gebiete d. Agrikulturphysik, 1879, p. 44J. 



