MANtJRES. 205 



continued employment as a manure, especially so when it 

 is present in excessive quantities as is the case with a 

 great number of mounds. 



TAFLA. 



The presence of tafla is confined entirely to Upper 

 Egypt, where it exists in a natural state, and provides a 

 very large amount of manure of a valuable nature. It is 

 a nitrate-bearing clay, found in the desert hills in the 

 southern provinces. 



It is usually a bluish clay, though sometimes a marl, 

 containing varying proportions of nitrogen in the form of 

 nitrate of soda. It occurs chiefly south of Keneh, in fact 

 north of this it seems to be practically unknown. Beyond 

 Keneh, however, it exists in large quantities and is in 

 common use, except where good coufri mounds are found 

 in close proximity to the land. 



On the basin lands of Upper Egypt the question of 

 manure supply has not attained that importance which it 

 has assumed in Lower Egypt, or on perennially irrigated 

 land. The interdependence of water and manure has 

 already been referred to. It may again be stated that the 

 supply of the one without the other can only be attended 

 with a limited amount of success. 



Where we have rich virgin land, water alone for a time 

 may be sufficient, and where the soil receives annually 

 a good layer of rnud, manure may be to a very great 

 extent, and perhaps entirely, dispensed with. Any exten- 



