76 EGYPTIAN AGRICULTURE. 



2. The soil contains more plant food for it receives a 

 little from the rain, it gets fresh virgin soil from the 

 irrigation water, the manure is applied to it, and the dead 

 leaves, stems, and most of the roots of plants are left on 

 or in it. 



3. The plant food in the soil is more available for the 

 plant because near the surface the weathering agents are 

 more active. 



4. The nitrogen collecting bacteria of the nodules on 

 the leguminous plants are chiefly confined to the soil, and 

 the rich residue of those crops enrich the soil with nitro- 

 genous plant food. 



5. The soil contains more air and is more penetrable 

 and therefore in it the plant roots are larger and healthier. 



Since the subsoil is not tilled, it is more closely packed 

 and harder than the soil and although it might contain 

 as much total plant food yet it would, under ordinary 

 circumstances, always contain less available food for 

 plants on account of the slower rate at which weather- 

 ing takes place in it. The best subsoil is a lightish loam : 

 a sandy subsoil is deficient in water and a clay subsoil is 

 too wet and tenacious for the healthy growth of plant 

 roots. 



The nature of a soil is an important factor both in regard 

 to the growth of crops and the cultivation of the soil. In 

 Egypt the soils are sandy or loamy or clayey. The loam 

 has the most general distribution, the clay occurs in small 

 patches, and the sandy soils are principally found skirting 

 the edges of the deserts. The mineral characters of the 

 soil and subsoil show great variations even within limited 



