82 AGRICULTURAL EXPLORATIONS IN ALGERIA. 



never made into hay. As it grows more or less throughout the win- 

 ter, a sufficient suppl}' of green forage can generally be obtained at 

 all seasons. 



The alfalfa grown at Tougourt is of fine quality, succulent, thin 

 stemmed, almost perfectly smooth, and having large, thin leaves. 

 These qualities are dou))tless mainly due to its ))eing more or less 

 shaded by the date palms and to the frequent watering it receives; 

 for, at the experiment station at Rouiba, alfalfa from Tougourt had 

 wiry stems and was hairier even than the American alfalfa grown 

 beside it. 



The crust of salt that often covers the ditch banks and strips of bare 

 soil between the plats of alfalfa is sufficient evidence that the soil of 

 the oases is very saline. The water used in irrigating likewise has a 

 high salt content. Yet there are reasons for believing that the amount 

 of salt to which the plants are actually exposed during gei'mination and 

 while still very young is not so great as would at first appear to ])e the 

 case. The soil is light and loam}-, and hence easily drained. Especial 

 attention is given to this matter by the Arabs, drainage ditches being 

 dug in the gardens at frequent intervals. These end blindlv, as 

 there is no natural outlet for them. Nevertheless, they must have 

 a considera))le degree of efficienc}^, for the alfalfa that is nearest the 

 ditches is always in decidedl}^ better condition than that which is far- 

 ther away. With this provision for drainage and the very frequent 

 irrigations given, it is probable that a very considerable amount of 

 salt is leached out of the uppermost layers of the readily permeabje 

 soil. The date palms that shade the ground do their part by keeping 

 down evaporation and thus retarding the return of the salts to the 

 surface. Finally, the oasis soils are very rich in gypsum (calcium 

 sulphate). This, as is well known, neutralizes to a considerable degree 

 the harmful effect of other salts in the soil. 



At the small oasis of Kuda-Asli, a few miles from Tougourt, alfalfa 

 was found growing in the open, unshaded 1)}' palms or other trees. 

 Examination of the soil showed that the plants were making a fairl}^ 

 good growth, although the stand was thin, in the presence of 1.36 per 

 cent of salts in the first foot of soil. A good growth occurred in the 

 presence of 0.9 per cent in the first and 0.5 per cent in the second foot. 

 Finally, an excellent stand had been obtained in soil that contained 

 from 0.4 to 0.6 per cent of salts in the first and second feet. The 

 water used for irrigating this field contained 4G0 parts of salt per 

 100,000. The soil is a sand}^ loam, and is so full of gypsum that at a 

 depth of about 2 feet a veritable hardpan of this substance is encoun- 

 tered. The presence of this dense stratum would be expected to 

 interfere seriously with drainage, to which the texture of the soil is 

 otherwise well adapted. Consequently, notwithstanding the condi- 

 tions mentioned in the preceding paragraph as tending to counteract 



