33 



its energy must be devoted to replenishing feeble tissue, instead of 

 niiiking new tissue for growth. The cane once stunted or injured will 

 feel the effects throughout its life. The rntoon crop may partly recov- 

 er but instead of four or five profitable cuts there will probably be 

 but three. 



The yield of cane per acre is naturally influenced by an excess of 

 alkali not only because there may be small areas on which nothing 

 will grow but also because the cane that is grown may be stunted. 



It has been interesting to observe that the alkali has not seemed to 

 influence the manufacturing qualities of the cane to the extent that 

 might be expected; the manipulation of irrigation water has seemed to 

 exert a greater influence over them than do the salts in the soil. On a 

 strongly alkaline soil, with an excess of water, a cane will be produc- 

 ed of fair fibre (14 %}, low sugar (13 %\ low purity (80 to 85 %), 

 high glucose (.7 to 1 ^), low density, high ash and high gums. On 

 the same kind of soil but with a moderate supply of water, a cane 

 with the opposite qualities will be produced, that is, high fibre, high 

 sugar, high density, high purity, low glucose and low ash. 



EFFECTS OF IRRIGATION ON ALKALI SOILS. 



Water parsing over an alkali spot from one section of cane to an- 

 other m:iy take up a portion of the salt and deposit it on the section 

 below. Or, if the water is held on the soil it may increase the alkali 

 in two ways; by adding to the already accumulated alkalies in the 

 soil, and by dissolving the salts in the under strata which on evapo- 

 ration will be brought to the surface. 



Through years of cultivation and irrigation, not only has the topog- 

 raphy of tiie valley been changed with reference to the alkali depos- 

 its, but the chemical constituents of the alkali have been modified. 

 Some of the elements, potash in particular in a most available form, 

 have been removed. The continued application of irrigation water on 

 some of these lands has dissolved out a portion it along with other 

 elements and carried them to the lower lands near the sea, The lesa 

 soluble phosphoric acid was left behind. If this washing had not gone 

 on, the soluble potash salts would have remained in the soil and 

 there would have been little need today for applying potash on some 

 of the soils. There probably are soils in Peru well supplied with pot- 

 ash and therefore no universal recommendation can be made for the 

 application of potash on all Peruvian soils. The analyses of Cartavio 



