J. A. Prescott 231 



NitrificdlloH itnder the irheat crop. 



Wheat in Egypt usually follows the cotton or the maize crop, and 

 on weak land responds to nitrogenous manures but not so readily as 

 does maize. The few results tabulated below show that as in England 

 nitrates do not accumulate under the wheat crop. The amounts of 

 nitrate found in the stubbles of the wheat in the case of the summer 

 fallow is a further illustration of this ])oint. 



Table XVI. 



AnwHnls of nil rate found in the mil of wheat field. 1917-1918. 



The Slimmer fallow {" sheraqi"). 



One of the most characteristic periods of the Egyptian farm rotation 

 is the period following the winter crops. The land is already in a fairly 

 dry condition when the crop is removed and it is allowed to remain 

 fallow without treatment of any kind until sufficient water is available 

 for the "Nili"' crop. The earliest date at which the first irrigation of 

 the sheraqi is allowed is fixed by law and depends on the prosjiects of 

 the Nile flood. A very intensified form of sheraqi is observed in Upper 

 Egypt on the basin lands which only receive water at each Nile flood 

 and are fallow from May until August. A number of nitrate determina- 

 tions was made on sheraqi soils immediately after the removal of the 

 winter crops in some cases, and in others after an interval or just before 

 the irrigation. The moisture after the removal of the crop may be 

 fairly high according to the previous irrigation of the field, but the soil 

 soon dries out and the moisture content falls to 6 or 7 %, or a little 

 below the air dried condition that is reached under laboratory conditions. 

 The preceding crop has removed most of the soluble nitrogen from the 

 soil. Even after bersim little nitrate is found unless stock have just 

 been feeding oo the land. See Table XVII. 



