AGRICULTURE AND RURAL ECONOMY. 543 



same soil, in samples taken from a large number of places. 

 The admixture of humus in the surface-soil, the disintegra- 

 tion, and other circumstances were found to have great in- 

 fluence upon the absorption. The ploughing of a strongly 

 absorptive clay requires care, or a diminished yield may re- 

 sult. In laying bare the roots of some trees near Berlin, the 

 soil among: the roots was found to have become bleached, 

 while the surrounding soil was yellowish-brown from the 

 presence of iron, showing that iron had been removed; 100 

 grams of the brown sand absorbed ammonia corresponding 

 to 12 centigrams of nitrogen, while 100 grams of the bleached 

 absorbed only 8.5 centigrams. 



Use of Lime and Marl in Soils. 



In the very interesting article on the Influence of Chemical 

 Discoveries on the Progress of English Agriculture, from 

 which we have already quoted, Dr. Voelcker says: "The in- 

 vestigations on the absorption of potash by various soils has 

 also thrown a new light on the special use of lime and marl 

 on poor sandy soils. Every farmer knows how essential 

 lime is for the healthy growth of every kind of agricultural 

 produce. On soils destitute of lime, most crops, especially 

 green crops, are subject to disease, and consequently roots 

 fail altogether on such land, even if it has been liberally ma- 

 nured with good farm-yard manure or guano. . . . The reme- 

 dy for such failures, which are not at all uncommon in locali- 

 ties where poor sandy soils prevail, is a good dose of lime or 

 marl, and then, and only then, farm-yard manure or guano 

 may be applied to the greatest advantage. . . . The most lib- 

 eral application of farm-yard manure of the best quality nev- 

 er produces so beneficial or lasting an effect on poor sandy 

 soils as when they have been previously well marled or 

 limed. There are some soils which swallow up manure with, 

 so to speak, an insatiable appetite, without ever feeling the 

 better for the manure they are appropriately called very 

 hunsTV. On all such soils much manure is wasted, or the 

 most is not made of it if, previously to the application of 

 farm-yard manure, guano, etc., the land has not received a 

 good dose of lime." 



