56 



TRUCK-FARMING AT THE SOUTH. 



serve manure like a clay soil." (p. 177.) "On light 

 sandy soil, such an annual dressing of manure (fourteen 

 tons barn-yard manure per acre) would, in the course of 

 a few years, make the land too rich for wheat." (p. 176.) 

 "On sandy land, the manure will decompose more 

 rapidly, and act quicker than on clayey or loamy land." 

 (p. 295.) "To what, then, is the power of soils to 

 arrest ammonia, potash, magnesia, phosphoric acid, etc., 

 owing? The above experiments lead to the conclusion 

 that it is due to the clay which they contain. Pure 

 sand was found not to possess it." (p. 218.) "A 

 London clay contained about seven thousand pounds of 

 ammonia per acre, equivalent to the quantity contained 

 in seven hundred tons of barn-yard manure." (p. 221.) 

 " Clay mixed with manure arrests, or checks decomposi- 

 tion. Sand has no such effect. If anything, it favors a 

 more active decomposition, and hence, manure acts much 

 more rapidly on sandy land than on clay land." (p. 268.) 

 A table by Lawes and Gilbert shows the produce of 

 wheat per acre on the clay soil of Eothamsted for twenty 

 consecutive years without any manure: 



