WIIKAT Sf)lI,S OK TllK AI.KX A XDKI A DIVISION. J35 



If on any soil within ihe area wheal is al ])ix'scnt 

 (loino^ well, it is highly essential that such soils should be thor- 

 oughly in\estigate(l. in order to compare them with the soils 

 which have ceased to prtxluce good wheat crops. If we know 

 the conditions under which good crops are produced — and ])ro- 

 duced profitably, we shall have a standard of comi^arison for 

 other soils within the area. 



Acknowledgments are due to Mr. G. G. Malan, B.A.. for 

 his assistance in the determination of moisture, loss on ignition, 

 lime, magnesia, potash and phosphoric oxide in these soils. 



Summary. 



1. For some years past, deterioration has been obser\ed in 

 the crops — especially wheat — grown on certain farms in the 

 Alexandria Division. 



2. A. series of twenty soils — ten cultivated and ten virgin — 

 was accordingly collected from the affected farms, where culti- 

 vation had been carried on for many years w'ithout manure. 



3. Mechanical analysis showed the soils to range in physical 

 character from medium sands to fine sandy loams, the propor- 

 tions of very fine sand, silt and clay together varying between 

 16 and 63 per cent., while pebljles, gravel and coarse sand were 

 practically absent. 



4. The medium sands are xery light in texture for wheat- 

 growing, and according to Wiley, a soil containing as much as 

 70 per cent, of very fine sand, silt and clay is still too light 

 for profitable wheat production. 



5. The Southern Maryland wheat soils of the lighter type 

 contain about 75 per cent, of very fine sand, silt and clay, and 

 the heavier ty])e of wheat soils contain about 95 per cent. 



6. The wheat soils of the South-Eastern Counties of luig- 

 land are generally heavier than those of Alexandria, and even 

 those which are lightest in texture are well su])plied with sub- 

 soil water. 



7. The general conclusion, therefore, is that, judged by 

 English and United States standards, the Alexandria soils are 

 rather light for wheat-growing. Wheat soils, moreover, should 

 retain a considerable amount of water, and be fairly well sup- 

 plied with organic material. In both these latter resj^ects the 

 Alexandria soils fall short. They would be impro\ed, iioth 

 physically and chemically, by admixture of river silt dejwsits. 



8. Rain and irrigation tend to denude the surface soils of 

 silt and- clay, and so render soils which are already inclined to 

 sandiness all the less suited for wheat. .Assuming the corres- 

 pondence between the samples of cultivated and of virgin soils 

 from Alexandria to be true, some of them have lost, under 

 cultivation, nearly one-half of the silt and clay which they orig- 

 inally contained. 



