44 AGRICULTUEAL EXPLORATIONS IN ALGERIA. 



of salts in the soil. We nia}' be excused for (luotiiig at some length 

 from this author." 



It is sea salt — that is, true salt — that is generally found in Algeria, but magnesium 

 salts have also been found in several vineyards. As for the alkali salts, or "black 

 alkali," we have not yet come across them. They probably appear, however, when 

 circumstances favoral)le to their formation exist. * * * But if their existence is 

 transient, if washing does not take place to separate them from the other salts, it is 

 difficult to determine their presence. 



In 1876 Pichard called attention to the presence of carbonate of sodium in several 

 waters in Oran Department, accompanied by sulphates of sodium and calcium and 

 chlorids of calcium and magnesium, sometimes by small quantities of alkali nitrates 

 and traces of ammonium salts. These waters give an alkaline reaction and contain 

 from 0.2 gram to 20 grams of sodium carbonate per liter. 



While the salt is directly harmful, it is also indirectly injurious ))y hindering the 

 nitrification of the nitrogenous matter existing in the soil or added to it by manure. 

 Hence it interferes with the alimentation of plants. 



In vineyards salt manifests itself in spots which differ in aspect according as they 

 are old or new. When the salt is in small quantities in the soil, or, rather, when 

 the soil still contains a considerable proportion of water, or when, again, the salt 

 reaches only a part of the zone of soil occupied by the roots, the spots are charac- 

 terized by a simple wilting of the vegetation. 



At other times the damage caused by the salt is sudden and nmch more pro- 

 nounced. The places attacked then take the form of circular spots. The branches 

 of the vines that bear grapes lose their leaves and dry up, and the grapes do not 

 reach complete maturity. 



In 1898 and in 1899, at the time of our visit [to the vineyards of Oran Department], 

 we saw numerous spots presenting these characteristics. Such spots were occupied 

 by vines loaded with grapes, but the branches had completely lost their leaves. All 

 around them the vines were green and were well loaded with a good crop of grapes. 



In the older spots, which are sometimes very extensive, most of the vines are 

 dead. We find, however, here and there, some vines that have resisted the salt and 

 have been able to put out badly developed branches bearing a few grapes of poor 

 quality. These old spots, although due to salt, much resemble those caused by 

 phylloxera. 



The reclaiming of salt land is difficult to accomplish in Algeria. The rainfall is 

 always insufficient to bring about reclamation, and the supply of irrigation water is 

 also scanty. 



For the present we must try to get along with the salt, doing our best to prevent 

 its becoming too injurious. This can be done by working the soil to a depth of 20 

 inches, so that the rain water can be stored in that depth of the soil. In this way 

 the fresh water can be prevented from penetrating sufficiently deep to dissolve the 

 salt and by its pre.sence it restrains the salt from rising. It is necessary, of course, 

 by superficial cultivation to break up the capillarity of the soil, so as to reduce evap- 

 oration to a mininuun. 



Drainage ditches can also be used in certain lands for carrying off tlie salty water 

 of the lower depths of the soil. Ditches can also be used in certain cases to prevent 

 the invasion of new land by the sheet of salt water. 



Saline soils of purely natural orioin are found in and near the chotts 

 which occupy depressions and receive the drainage of the surrounding 

 land. In such places salt has been accumulating through long ages. 



« Agrologie de 1' Algeria, 1900, pp. 66, 58, 59, 71, 72, 77, 78, 80, 81,-89, 90. 



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